agilogo.png, 10kB

LABORATORY INSTRUMENTS FOR MEASUREMENTS
OF MAGNETIC PROPERTIES OF ROCKS

Full list of publications

Full List of Publications
Matching entries: 0
settings...
Hrouda, F. & Ježek, J. (2017), "Role of single-domain magnetic particles in creation of inverse magnetic fabrics in volcanic rocks: A mathematical model study"; Studia Geophysica et Geodaetica, Vol. 61 (1) , pp. 145-161
Abstract: The role of single-domain (SD) magnetic particles in creation of inverse magnetic fabrics is investigated on simple mathematical models using a realistic estimate for SD intrinsic susceptibility. In contrast to the fraction created by multi-domain (MD) particles, in which the anisotropy of magnetic susceptibility (AMS) is controlled by both the grain AMS and intensity of the preferred orientation of the particles, the AMS of the SD fraction is controlled solely by the intensity of the preferred orientation. The degree of AMS of ensemble of SD grains with a preferred orientation is therefore much higher than that of the same ensemble of MD particles implying the existence of frequent inverse magnetic fabrics. However, the occurrence of inverse magnetic fabrics due to SD particles is more the exception than the rule. Consequently, the amounts of SD particles is probably in general low. Nevertheless, the presence of SD particles in amounts insufficient to create inverse magnetic fabrics may diminish the whole rock AMS substantially. This can be one of the reasons for relatively low AMS in volcanic rocks whose magnetic particles may be really small obeying the conditions for the existence of SD particles.
BibTeX:
@article{Hrouda2017,
  author = {Hrouda, František and Ježek, Josef},
  title = {Role of single-domain magnetic particles in creation of inverse magnetic fabrics in volcanic rocks: A mathematical model study},
  journal = {Studia Geophysica et Geodaetica},
  year = {2017},
  volume = {61},
  number = {1},
  pages = {145--161},
  url = {http://link.springer.com/10.1007/s11200-015-0675-6},
  doi = {http://dx.doi.org/10.1007/s11200-015-0675-6}
}
Piedrahita, V., Bernet, M., Chadima, M. et al. (2017), "Detrital zircon fission-track thermochronology and magnetic fabric of the Amagá Formation (Colombia): Intracontinental deformation and exhumation events in the northwestern Andes"; Sedimentary Geology, Vol. 356 , pp. 26-42
Abstract: New detrital zircon-fission track (ZFT) and magnetic fabric data are presented to constrain the time of deposition, provenance and deformation of the of Lower and Upper members of the Amagá Formation in the Amagá Basin. The Amagá Basin is located in the northern Andes, between the Western and Central Cordilleras of Colombia. The Amagá Formation was deposited in a transpressive geodynamic context and is allegedly synchronous with tectonic events such as the Andean orogeny and the Panama-Choco Block collision with the northwestern South American Plate. Detrital ZFT data confirm an Oligocene age for the Lower Member and a middle-Miocene age for the Upper Member of the Amagá Formation. In addition to constraining the depositional age, the ZFT data presented in this study also reflect Paleocene-Eocene, late to early Oligocene and late to middle Miocene cooling in sediment source areas mainly located in the Central and Western Cordilleras of Colombia. These ages can be associated with regional exhumation events in the central and northern Andes of South America. Collisional stages of the Panama-Choco Block against northwestern South America, subduction of the Farallon-Nazca Plate and strike-slip reactivation periods of the Cauca-Romeral fault system, caused NW-SE compression and NE-SW simple shear in the Amagá Basin. This deformational regime, identified by magnetic fabric data, induces syn- and post-depositional deformation over the Amagá Formation.
BibTeX:
@article{Piedrahita2017,
  author = {Piedrahita, V.A. and Bernet, M. and Chadima, M. and Sierra, G.M. and Marín-Cerón, M.I. and Toro, G.E.},
  title = {Detrital zircon fission-track thermochronology and magnetic fabric of the Amagá Formation (Colombia): Intracontinental deformation and exhumation events in the northwestern Andes},
  journal = {Sedimentary Geology},
  year = {2017},
  volume = {356},
  pages = {26--42},
  url = {http://www.sciencedirect.com/science/article/pii/S0037073817301239},
  doi = {http://dx.doi.org/10.1016/j.sedgeo.2017.05.003}
}
Závada, P., Calassou, T., Schulmann, K. et al. (2017), "Magnetic fabric transposition in folded granite sills in Variscan orogenic wedge"; Journal of Structural Geology, Vol. 94 , pp. 166-183
Abstract: New approach involving evaluation of anisotropy of magnetic susceptibility (AMS) data in stereoplots and Jelínek's Pj–T space, Vollmer's eigenvalue and microstructural analyses is proposed to discriminate between homogeneous and superposed deformation in granites. This method is used to decipher the internal AMS fabric and microstructural evolution of a folded array of granitic sills. The studied major sill shows a fabric and microstructural zonality marked by submagmatic and high-temperature Type I planar-linear fabric developed at sill margins, and the transpositional Type II subsolidus fabrics that formed at high to medium temperature deformation in the sill core. While Type I fabric is associated with dip slip magnetic lineations, Type II subsolidus fabrics are marked by subhorizontal magnetic lineations striking parallel to the long axis of the sill. The structural reconstruction of the fabrics in the granite and the host rocks as well as new U–Pb zircon ages suggest coeval emplacement of horizontal and vertical sills accounting for significant weakening of the host rock–magma multilayer. The model of folding of such multilayer and extrusion of residual magma parallel to axial planes is discussed with respect to structural record in other syn-contractional granite sill arrays forming sheeted plutons worldwide.
BibTeX:
@article{Zavada2017,
  author = {Závada, Prokop and Calassou, Thibaud and Schulmann, Karel and Hrouda, František and Štípská, Pavla and Hasalová, Pavlína and Míková, Jitka and Magna, Tomáš and Mixa, Petr},
  title = {Magnetic fabric transposition in folded granite sills in Variscan orogenic wedge},
  journal = {Journal of Structural Geology},
  year = {2017},
  volume = {94},
  pages = {166--183},
  url = {http://linkinghub.elsevier.com/retrieve/pii/S019181411630195X},
  doi = {http://dx.doi.org/10.1016/j.jsg.2016.11.007}
}
Hrouda, F., Chadima, M., Ježek, J. et al. (2016), "Anisotropy of out-of-phase magnetic susceptibility of rocks as a tool for direct determination of magnetic subfabrics of some minerals: an introductory study"; Geophysical Journal International, Vol. 208 (1) , pp. 385-402
Abstract: The magnetic susceptibility measured in alternating field can in general be resolved into a component that is in-phase with the applied field and a component that is out-of-phase. While in non-conductive diamagnetic, paramagnetic and many ferromagnetic materials the phase is effectively zero, in some ferromagnetic minerals, such as pyrrhotite, hematite, titanomagnetite or small magnetically viscous grains of magnetite, it is clearly non-zero. The anisotropy of out-of-phase susceptibility (opAMS) can then be used as a tool for the direct determination of the magnetic subfabrics of the minerals with non-zero phase. The error in determination of out-of-phase susceptibility non-linearly increases with decreasing phase angle. This may result in imprecise determination of the opAMS in specimens with very low phase angle. The degree of opAMS is higher than that of ipAMS, which may in contrast result in slightly increasing precision n the opAMS determination. It is highly recommended to inspect the results of the statistical tests of each specimen and to exclude the specimens whose opAMS is determined with insufficient precision from further processing. In rocks, whose magnetism is dominated by the mineral with non-zero out-of-phase susceptibility, the principal directions of the opAMS and ipAMS are virtually coaxial, while the degree of opAMS is higher than that of ipAMS. In some specific cases, the opAMS provides us with similar data to those provided by anisotropies of low-field dependent susceptibility and frequency-dependent susceptibility. The advantage of the opAMS compared to the other two anisotropies is its simultaneous measurement with the ipAMS during one measuring process, while the other two anisotropies require the AMS measurements in several fields or at least at two operating frequencies.
BibTeX:
@article{Hrouda2016,
  author = {Hrouda, František and Chadima, Martin and Ježek, Josef and Pokorný, Jiří},
  title = {Anisotropy of out-of-phase magnetic susceptibility of rocks as a tool for direct determination of magnetic subfabrics of some minerals: an introductory study},
  journal = {Geophysical Journal International},
  year = {2016},
  volume = {208},
  number = {1},
  pages = {385--402},
  url = {http://dx.doi.org/10.1093/gji/ggw399}
}
Hrouda, F., Pokorný, J. & Chadima, M. (2015), "Limits of out-of-phase susceptibility in magnetic granulometry of rocks and soils"; Studia Geophysica et Geodaetica, Vol. 59 (2) , pp. 294-308
Abstract: Frequency-dependent magnetic susceptibility enables the amount of newly created ultrafine superparamagnetic particles to be assessed, being therefore important tool for environmental and palaeoclimatologic research. It was shown recently that the out-of-phase susceptibility is also able to provide this information. In the present paper we investigate the accuracy of the measurement of the out-of-phase susceptibility at all three frequencies of the MFK1-FA Kappabridge as well as accuracy in the determination of the XON parameter, which is the microscopic equivalent of the XFN parameter characterizing the frequency-dependent susceptibility. The method is tested on samples of cave sediments, a loess/palaeosoil sequence, and artificial specimens. The detection limit in determining the XON parameter is about 3%, which is only slightly worse than the reproducibility of the XFN parameter (about 1%). A new measuring technique is proposed making the accuracy in determination of the XON parameter comparable to that in determining XFN parameter. The main advantage of the out-of-phase susceptibility is that it is measured simultaneously with the in-phase susceptibility during one measuring process. This is very useful in working with large specimen collections as in palaeoclimatology and environmental magnetism.
BibTeX:
@article{Hrouda2014,
  author = {Hrouda, František and Pokorný, Jiří and Chadima, Martin},
  title = {Limits of out-of-phase susceptibility in magnetic granulometry of rocks and soils},
  journal = {Studia Geophysica et Geodaetica},
  year = {2015},
  volume = {59},
  number = {2},
  pages = {294--308},
  url = {http://dx.doi.org/10.1007/s11200-014-0948-5 http://link.springer.com/10.1007/s11200-014-0948-5},
  doi = {http://dx.doi.org/10.1007/s11200-014-0948-5}
}
Hrouda, F., Buriánek, D., Krejčí, O. et al. (2015), "Magnetic fabric and petrology of Miocene sub-volcanic sills and dykes emplaced into the SW Flysch Belt of the West Carpathians (S Moravia, Czech Republic) and their volcanological and tectonic implications"; Journal of Volcanology and Geothermal Research, Vol. 290 , pp. 23-38
Abstract: Magnetic fabrics were investigated in the sub-volcanic bodies occurring within the SW Flysch Belt of the Western Carpathians. Magnetite or low-Ti titanomagnetite is the principal carrier of the anisotropy of magnetic susceptibility (AMS) in these rocks, though various Fe–Ti oxides were also identified in minor amounts. The magnetic fabric in almost all sills and dykes is conformable to the shapes of the bodies and no doubt originated through more or less free magma flow that requires relatively open voids to be injected, that likely originated in an extensive tectonic regime. In an ankaramite sill, where the rock creates typical hexagonal columns, the magnetic fabric is related rather to the column axes than to the overall shape of the sill. The magnetic fabric formation in this sill is controlled by the post-emplacement process of the creation of the columns. At some studied localities, signs of post-magmatic Middle Miocene tectonic deformation are observed in the field, the youngest known in the Flysch Belt. As the magnetic fabric is unrelated to those signs, we conclude that these young tectonic movements did not penetrate ductilely in the volume of the volcanic body. It seems that the strain was focused to thin zones along the faults, since it did not change the preferred orientation of magnetic minerals in the rock volume substantially.
BibTeX:
@article{Hrouda2015,
  author = {Hrouda, František and Buriánek, David and Krejčí, Oldřich and Chadima, Martin},
  title = {Magnetic fabric and petrology of Miocene sub-volcanic sills and dykes emplaced into the SW Flysch Belt of the West Carpathians (S Moravia, Czech Republic) and their volcanological and tectonic implications},
  journal = {Journal of Volcanology and Geothermal Research},
  year = {2015},
  volume = {290},
  pages = {23--38},
  url = {http://www.sciencedirect.com/science/article/pii/S0377027314003746},
  doi = {http://dx.doi.org/10.1016/j.jvolgeores.2014.12.001}
}
Tomek, F., Žák, J. & Chadima, M. (2015), "Granitic magma emplacement and deformation during early-orogenic syn-convergent transtension: The Staré Sedlo complex, Bohemian Massif"; Journal of Geodynamics, Vol. 87 , pp. 50-66
Abstract: The Late Devonian Staré Sedlo complex, Bohemian Massif, was emplaced as a subhorizontal sheeted sill pluton into a transtension zone. The transtensional setting is documented by strong constrictional fabric, corroborated by the anisotropy of magnetic susceptibility (AMS), with variably developed subhorizontal magmatic to solid-state foliation suggesting vertical shortening. Intrusive contacts of the granitoids with metapelitic screens and tapered sill tips indicate that magma wedging was the dominant process of sill propagation. The sills exhibit two intrusive styles, ranging from thin lit-par-lit injections to widely spaced meter-thick sills. These two styles are interpreted as reflecting variable viscosities of intruding magma where low-viscosity magma percolated along foliation planes whereas high-viscosity magma produced more localized thicker sills. We propose that the magma/host rock system in transtension must have evolved from initial crack tip propagation and vertical expansion due to new magma additions through conduit flow to ductile thinning after the magma input had ceased. The sill emplacement and their subsequent deformation are then interpreted as recording early-orogenic syn-convergent sinistral transtension along the rear side of an upper-crustal wedge, which was extruded both upward and laterally in response to subduction and continental underthrusting.
BibTeX:
@article{Tomek2015,
  author = {Tomek, Filip and Žák, Jiří and Chadima, Martin},
  title = {Granitic magma emplacement and deformation during early-orogenic syn-convergent transtension: The Staré Sedlo complex, Bohemian Massif},
  journal = {Journal of Geodynamics},
  year = {2015},
  volume = {87},
  pages = {50--66},
  url = {http://www.sciencedirect.com/science/article/pii/S0264370715000265},
  doi = {http://dx.doi.org/10.1016/j.jog.2015.02.007}
}
Hrouda, F., Faryad, S. W., Chlupáčová, M. et al. (2014), "Magnetic fabric in amphibolized eclogites and serpentinized ultramafites in the Mariánské Lázně Complex (Bohemian Massif, Czech Republic): Product of exhumation-driven retrogression?"; Tectonophysics, Vol. 629 , pp. 260-274
Abstract: The largest body of metabasic rocks in the Bohemian Massif, the Mariánské Lázně Complex (MLC), represents an Early Paleozoic ophiolite complex, which experienced poly-metamorphic evolution with an early high-pressure amphibolite, followed by eclogite and subsequent amphibolite facies overprint. This study aims to investigate the fabric relationships among the rock bodies and to analyze the deformation–recrystallization history of the MLC using the anisotropy of magnetic susceptibility (AMS). Magnetic susceptibility of the MLC rocks varies according to the presence of para- and ferromagnetic minerals as well as according to the primary lithologies. In weakly magnetic rocks (Km<1×10−3 [SI]), the main carrier of susceptibility is paramagnetic mafic silicates, amphibole and biotite in amphibolites, clinopyroxene and garnet in eclogites, olivine and serpentine minerals in serpentinized ultramafite, and amphibole in gabbro. In highly magnetic rocks (Km≫1×10−3), ferromagnetic minerals, such as magnetite, titanomagnetite, general Fe–Ti oxides, and subordinately also pyrrhotite can play an important role. The results of AMS indicate that the orientation of magnetic minerals in most rocks is related to the last exhumation and retrogression event that occurred in amphibolite facies conditions. However, there are some well preserved eclogites possessing the magnetic fabrics that are at least partially related to prograde or peak PT conditions during metamorphism. In addition, massive metagabbros that suffered only weak deformation partially preserve the intrusive magnetic fabrics.
BibTeX:
@article{Hrouda2014a,
  author = {Hrouda, František and Faryad, Shah Wali and Chlupáčová, Marta and Jeřábek, Petr},
  title = {Magnetic fabric in amphibolized eclogites and serpentinized ultramafites in the Mariánské Lázně Complex (Bohemian Massif, Czech Republic): Product of exhumation-driven retrogression?},
  journal = {Tectonophysics},
  year = {2014},
  volume = {629},
  pages = {260--274},
  url = {http://www.sciencedirect.com/science/article/pii/S0040195114000705 http://linkinghub.elsevier.com/retrieve/pii/S0040195114000705},
  doi = {http://dx.doi.org/10.1016/j.tecto.2014.01.034}
}
Hrouda, F. & Ježek, J. (2014), "Frequency-dependent AMS of rocks: A tool for the investigation of the fabric of ultrafine magnetic particles"; Tectonophysics, Vol. 629 , pp. 27-38
Abstract: In some geological processes, new very fine-grained magnetic minerals may originate. The variation in content of these minerals is routinely investigated by frequency-dependent magnetic susceptibility, which is traditionally interpreted in terms of the presence of viscous superparamagnetic (SP) particles in addition to stable single domain (SSD) and multidomain (MD) magnetic particles. In addition, the fabric of these grains can be investigated through the frequency-dependent AMS. Through standard AMS measurement at different frequencies, one can evaluate the contribution of SP particles to the whole-rock AMS; appropriate methods were developed. Various rocks, soils and ceramics, showing frequency-dependent magnetic susceptibility, were investigated. Measurable changes of AMS with operating frequency were revealed and attempts are made of their fabric interpretation.
BibTeX:
@article{Hrouda2014b,
  author = {Hrouda, František and Ježek, Josef},
  title = {Frequency-dependent AMS of rocks: A tool for the investigation of the fabric of ultrafine magnetic particles},
  journal = {Tectonophysics},
  year = {2014},
  volume = {629},
  pages = {27--38},
  url = {http://www.sciencedirect.com/science/article/pii/S0040195114000882},
  doi = {http://dx.doi.org/10.1016/j.tecto.2014.01.040}
}
Zakharov, V. A., Rogov, M. A., Dzyuba, O. S. et al. (2014), "Palaeoenvironments and palaeoceanography changes across the Jurassic/Cretaceous boundary in the Arctic realm: case study of the Nordvik section (north Siberia, Russia)"; Polar Research, Vol. 33 (1) , pp. 19714
Abstract: The Jurassic/Cretaceous transition was accompanied by significant changes in palaeoceanography and palaeoenvironments in the Tethyan Realm, but outside the Tethys such data are very scarce. Here we present results of a study of the most complete section in the Panboreal Superrealm, the Nordvik section. Belemnite $18O data show an irregular decrease from values reaching up to +1.6‰ in the Middle Oxfordian and from +0.8 to −1.7‰ in the basal Ryazanian, indicating a prolonged warming. The biodiversity changes were strongly related to sea-level oscillations, showing a relatively low belemnite and high ammonite diversity during sea-level rise, accompanied by a decrease of the macrobenthos taxonomical richness. The most prominent sea-level rise is marked by the occurrence of open sea ammonites with Pacific affinities. Peak abundances of spores and prasinophytes correlate with a negative excursion in organic carbon $13C near the J/K boundary and could reflect blooms of green algae caused by disturbance of the marine ecosystem.Keywords: Biodiversity; stable isotopes; J/K boundary; Arctic Realm; palaeoceanography(Published: 25 March 2014)Citation: Polar Research 2014, 33, 19714, http://dx.doi.org/10.3402/polar.v33.19714
BibTeX:
@article{POLAR19714,
  author = {Zakharov, Victor A. and Rogov, Mikhail A. and Dzyuba, Oksana S. and Žák, Karel and Košt'ák, Martin and Pruner, Petr and Skupien, Petr and Chadima, Martin and Mazuch, Martin and Nikitenko, Boris L.},
  title = {Palaeoenvironments and palaeoceanography changes across the Jurassic/Cretaceous boundary in the Arctic realm: case study of the Nordvik section (north Siberia, Russia)},
  journal = {Polar Research},
  year = {2014},
  volume = {33},
  number = {1},
  pages = {19714},
  url = {http://www.polarresearch.net/index.php/polar/article/view/19714 https://www.tandfonline.com/doi/full/10.3402/polar.v33.19714},
  doi = {http://dx.doi.org/10.3402/polar.v33.19714}
}
Studýnka, J., Chadima, M. & Suza, P. (2014), "Fully automated measurement of anisotropy of magnetic susceptibility using 3D rotator"; Tectonophysics, Vol. 629 , pp. 6-13
Abstract: A 3D rotator (for MFK1-FA or MFK1-A Kappabridges) was developed to increase the speed and comfort of anisotropy of magnetic susceptibility (AMS) measurements. The 3D rotator rotates the specimen simultaneously about two axes with different velocities. The two-axis rotation enables the determination of 320 directional susceptibilities during a single anisotropy measurement. These directions are very well distributed on a sphere which makes the measuring design almost rotatable. The actual measurement is fully automated in such a way that, once the specimen is mounted into the rotator, it requires no additional manipulation to measure the full AMS tensor. The approximate duration of one anisotropy measurement is 1.5min. Fundamental ideas of data acquisition and processing, AMS tensor fitting and respective error analysis are described and discussed. Calculation of the anisotropy tensor, respective error analysis and immediate data visualization is provided by Safyr5 software. Examples comparing the 3D rotator data with previously developed systems of AMS determination are presented.
BibTeX:
@article{Studynka2014,
  author = {Studýnka, Jan and Chadima, Martin and Suza, Petr},
  title = {Fully automated measurement of anisotropy of magnetic susceptibility using 3D rotator},
  journal = {Tectonophysics},
  year = {2014},
  volume = {629},
  pages = {6--13},
  url = {http://www.sciencedirect.com/science/article/pii/S0040195114001152},
  doi = {http://dx.doi.org/10.1016/j.tecto.2014.02.015}
}
Tomek, F., Žák, J. & Chadima, M. (2014), "Magma flow paths and strain patterns in magma chambers growing by floor subsidence: a model based on magnetic fabric study of shallow-level plutons in the Štiavnica volcano–plutonic complex, Western Carpathians"; Bulletin of Volcanology, Vol. 76 (11) , pp. 873
Abstract: The Miocene Štiavnica volcano--plutonic complex, Western Carpathians, exposes two nearly coeval intra-caldera plutons, their roof (basement of a stratovolcano), and associated volcanic rocks. The complex thus provides insights into mechanisms of magma chamber growth beneath large volcanoes. As inferred from the anisotropy of magnetic susceptibility (AMS), these plutons were emplaced through significantly different processes: the diorite as a discordant stock with steep fabric and the granodiorite as a tabular, bell-jar pluton. In detail, we interpret that the latter was assembled in two stages. First, an upper ``layer'' intruded as a thin sill along a major subhorizontal basement/cover detachment. The subhorizontal magnetic fabric and strongly oblate AMS ellipsoid in this layer record intrusive strain where the magma flow paths were subparallel to the pluton roof. Second, in the lower ``layer'' of the pluton, magnetic foliations dip moderately to the ∼NW and ∼WNW to vertical and are associated with down-dip to subhorizontal lineations and prolate to weakly oblate shapes of the AMS ellipsoids. Such a fabric pattern is compatible with piecemeal floor subsidence, where magma flowed along multiple subsiding fault-bounded blocks. Based on this case example, we develop a conceptual model for magma flow paths and strain patterns for four main modes of floor subsidence: (1) piston (cauldron) subsidence is characterized by convergent flow and radial principal stretching above the magma chamber floor; (2) the piecemeal floor subsidence leads to steep to inclined magma flow paths in conduits along fault-bounded blocks; (3) asymmetric (trapdoor) subsidence produces first divergent flow paths near the conduit sides, changing into convergent paths in the narrower space near the kinematic hinge; and (4) symmetric cantilever (funnel) subsidence will lead to divergent flow from a central feeder and thus circumferential principal stretching of the magma. If the growing pluton develops a ``two-layer'' structure, all the flow paths and associated strains are affected by the flat-lying pluton roof and will convert into horizontal flattening as the roof is approached.
BibTeX:
@article{Tomek2014,
  author = {Tomek, Filip and Žák, Jiří and Chadima, Martin},
  title = {Magma flow paths and strain patterns in magma chambers growing by floor subsidence: a model based on magnetic fabric study of shallow-level plutons in the Štiavnica volcano–plutonic complex, Western Carpathians},
  journal = {Bulletin of Volcanology},
  year = {2014},
  volume = {76},
  number = {11},
  pages = {873},
  url = {http://dx.doi.org/10.1007/s00445-014-0873-z http://link.springer.com/10.1007/s00445-014-0873-z},
  doi = {http://dx.doi.org/10.1007/s00445-014-0873-z}
}
Chadima, M. & Studýnka, J. (2013), "Fully automated measurement of field-dependent AMS using MFK1-FA Kappabridge equipped with 3D rotator"; , Vol. 15 EGU General Assembly Conference Abstracts , pp. 1449
Abstract: Low-field magnetic susceptibility of paramagnetic and diamagnetic minerals is field-independent by definition being also field-independent in pure magnetite. On the other hand, in pyrrhotite, hematite and high-Ti titanomagnetite it may be clearly field-dependent. Consequently, the field-dependent AMS enables the magnetic fabric of the latter group of minerals to be separated from the whole-rock AMS. The methods for the determination of the field-dependent AMS consist of separate measurements of each specimen in several fields within the Rayleigh Law range and subsequent processing in which the field-independent and field-dependent AMS components are calculated. The disadvantage of this technique is that each specimen must be measured several times, which is relatively laborious and time consuming. Recently, a new 3D rotator was developed for the MFK1-FA Kappabridge, which rotates the specimen simultaneously about two axes with different velocities. The measurement is fully automated in such a way that, once the specimen is inserted into the rotator, it requires no additional manipulation to measure the full AMS tensor. Consequently, the 3D rotator enables to measure the AMS tensors in the pre-set field intensities without any operator interference. Whole procedure is controlled by newly developed Safyr5 software; once the measurements are finished, the acquired data are immediately processed and can be visualized in a standard way.
BibTeX:
@inproceedings{Chadima2013,
  author = {Chadima, Martin and Studýnka, Jan},
  title = {Fully automated measurement of field-dependent AMS using MFK1-FA Kappabridge equipped with 3D rotator},
  booktitle = {EGU General Assembly Conference Abstracts},
  year = {2013},
  volume = {15},
  pages = {1449}
}
Hrouda, F., Faryad, S. W., Franěk, J. et al. (2013), "Magnetic fabrics in garnet peridotites–pyroxenites and host felsic granulites in the South Bohemian Granulites (Czech Republic): Implications for distinguishing between primary and metamorphism induced fabrics"; Gondwana Research, Vol. 23 (3) , pp. 956-972
Abstract: In the high-grade Moldanubian Zone of the European Variscides, numerous bodies of ultramafic rocks occur embedded in granulite. The anisotropy of magnetic susceptibility and its low-field variation as well as the anisotropy of magnetic remanence were used to investigate magnetic fabrics of some ultramafic bodies and host granulite. In granulite, the magnetic foliation is roughly parallel to the metamorphic foliation and the magnetic lineation is near the mineral alignment lineation. In ultramafite, the magnetic foliation is relatively scattered spatially, but mostly oriented in a different way than that in granulite. The magnetic lineation is also scattered, but still relatively well defined spatially. Again, its orientation is mostly different than that of granulite. The magnetic fabric in ultramafic rocks is therefore different from that in the host granulite even though both rock types underwent at least partially common structural history. The componental movements forming the granulite fabric, mostly during amphibolite facies retrograde metamorphism, were evidently not intensive enough to strongly overprint the magnetic fabric of ultramafite. The ultramafite is therefore strong enough to maintain its pre-metamorphism fabric even at such high temperatures and pressures that are characteristic of high amphibolite facies retrograde metamorphism.
BibTeX:
@article{Hrouda2013,
  author = {Hrouda, František and Faryad, Shah Wali and Franěk, J and Chlupáčová, Marta},
  title = {Magnetic fabrics in garnet peridotites–pyroxenites and host felsic granulites in the South Bohemian Granulites (Czech Republic): Implications for distinguishing between primary and metamorphism induced fabrics},
  journal = {Gondwana Research},
  year = {2013},
  volume = {23},
  number = {3},
  pages = {956--972},
  url = {http://www.sciencedirect.com/science/article/pii/S1342937X12002043},
  doi = {http://dx.doi.org/10.1016/j.gr.2012.05.020}
}
Hrouda, F., Pokorný, J., Ježek, J. et al. (2013), "Out-of-phase magnetic susceptibility of rocks and soils: a rapid tool for magnetic granulometry"; Geophysical Journal International, Vol. 194 (1) , pp. 170-181
Abstract: The magnetic susceptibility measured in alternating field can be resolved into a component that is in-phase with applied field and a component that is out-of-phase. While the former component is widely used for solving various geophysical, geological and environmental problems, the latter component is paid only minor attention. The theoretical relationship between the frequency-dependent in-phase susceptibility and the out-of-phase susceptibility is described by the $/2 law valid for materials in which the latter is due to presence of magnetic particles on transition between superparamagnetic and stable single-domain states possessing sufficiently wide distribution of relaxation times.To advantageously use the out-of-phase susceptibility, which is measured simultaneously with the in-phase susceptibility during one measuring process, in magnetic granulometry, new parameters, XON and XOD, are proposed approximately converting the out-of-phase susceptibility into the XFN and XFD parameters of the frequency-dependent susceptibility.The validity of the new parameters was tested through mathematical modelling and through investigating samples of various sediments. The correlations found seem to be acceptable from the practical point of view. In addition, simple test is proposed for checking that the out-of-phase susceptibility is solely due to the viscous phenomena and not due to electrical eddy currents or weak field hysteresis.As the out-of-phase susceptibility is measured automatically along the in-phase-susceptibility with some instruments and can be directly interpreted in magnetic granulometry terms, it is to recommend to be routinely investigated in solving various problems of environmental magnetism.
BibTeX:
@article{Hrouda2013,
  author = {Hrouda, František and Pokorný, Jiří and Ježek, Josef and Chadima, Martin},
  title = {Out-of-phase magnetic susceptibility of rocks and soils: a rapid tool for magnetic granulometry},
  journal = {Geophysical Journal International},
  year = {2013},
  volume = {194},
  number = {1},
  pages = {170--181},
  url = {http://gji.oxfordjournals.org/content/194/1/170.abstract},
  doi = {http://dx.doi.org/10.1093/gji/ggt097}
}
Hrouda, F., Moravčík, J. & Putiš, M. (2013), "Magnetická anizotropie mafických a ultramafických hornin na vybraných lokalitách Západních Karpat; tektonické implikace"; , MinPet 2013 , pp. 22-26
BibTeX:
@inproceedings{Hrouda2013a,
  author = {Hrouda, František and Moravčík, J and Putiš, Marián},
  title = {Magnetická anizotropie mafických a ultramafických hornin na vybraných lokalitách Západních Karpat; tektonické implikace},
  booktitle = {MinPet 2013},
  year = {2013},
  pages = {22--26}
}
Lehmann, Jé., Schulmann, K., Edel, J.-B. et al. (2013), "Structural and anisotropy of magnetic susceptibility records of granitoid sheets emplacement during growth of a continental gneiss dome (Central Sudetes, European Variscan Belt)"; Tectonics, Vol. 32 (3) , pp. 797-820
Abstract: Granitoid magmatic sheets emplaced syntectonically during growth of the Orlica-Śnieznik mantled gneiss dome (Central Sudetes, European Variscan belt) were examined by means of structural geology, quartz, and anisotropy of magnetic susceptibility (AMS) fabric studies. Magmatic emplacement was localized along the eastern transpressive margin of the high metamorphic core and below the low-grade detached mantle rimming the southern margin of the dome. In the first area, the magmatic sheets were emplaced parallel to the dilated subhorizontal foliation of an anisotropic pre-orogenic block. The resulting melt-host rock multilayer localized the transpressive zone along which the bulk of magma was emplaced. The AMS study shows an across-strike fabric zonation underlying a strongly transpressive solid-state deformation in the hanging-wall, magmatic subhorizontal fabric in the foot-wall and a transitional fabric in the center of the intrusion. In contrast, along the southern dome margin, magmatic sheets intruded along steep foliations of weakly metamorphic mantle rocks, and are affected by recumbent folding and subhorizontal shearing. The bulk of the sheets present a shallow-dipping magmatic foliation and an along-strike magmatic lineation. The variations of the quartz and magnetic fabrics are attributed to superimposition of pure shear-dominated ductile thinning followed by simple shear-dominated detachment onto the original steep fabric. AMS modeling confirms the role of variation of orientation of pre-intrusive anisotropy during progressive deformation on the resulting fabric pattern and helps explaining observed variations in fabric orientations and symmetries. This study highlights contrasting mechanical behavior of syntectonically emplaced magmas in different parts of a growing crustal-scale mantled gneiss dome. textcopyright 2013. American Geophysical Union. All Rights Reserved.
BibTeX:
@article{Lehmann2013,
  author = {Lehmann, Jérémie and Schulmann, Karel and Edel, Jean-Bernard and Ježek, Josef and Hrouda, František and Lexa, Ondrej and Chopin, Francis},
  title = {Structural and anisotropy of magnetic susceptibility records of granitoid sheets emplacement during growth of a continental gneiss dome (Central Sudetes, European Variscan Belt)},
  journal = {Tectonics},
  year = {2013},
  volume = {32},
  number = {3},
  pages = {797--820},
  url = {http://doi.wiley.com/10.1002/tect.20028},
  doi = {http://dx.doi.org/10.1002/tect.20028}
}
Hajná, J., Žák, J., Kachlík, Vá. et al. (2012), "Deciphering the Variscan tectonothermal overprint and deformation partitioning in the Cadomian basement of the Teplá–Barrandian unit, Bohemian Massif"; International Journal of Earth Sciences, Vol. 101 (7) , pp. 1855-1873
Abstract: The Teplá--Barrandian unit (TBU) has long been considered as a simply bivergent supracrustal `median massif' above the Saxothuringian subduction zone in the Variscan orogenic belt. This contribution reveals a much more complex style of the Variscan tectonometamorphic overprint and resulting architecture of the Neoproterozoic basement of the TBU. For the first time, we describe the crustal-scale NE--SW-trending dextral transpressional Krakovec shear zone (KSZ) that intersects the TBU and thrusts its higher grade northwestern portion severely reworked by Variscan deformation over a southeastern very low grade portion with well-preserved Cadomian structures and only brittle Variscan deformation. The age of movements along the KSZ is inferred as Late Devonian (textasciitilde380--370 Ma). On the basis of structural, microstructural, and anisotropy of magnetic susceptibility data from the KSZ, we propose a new synthetic model for the deformation partitioning in the Teplá--Barrandian upper crust in response to the Late Devonian to early Carboniferous subduction and underthrusting of the Saxothuringan lithosphere. We conclude that the Saxothuringian/Teplá--Barrandian convergence was nearly frontal during textasciitilde380--346 Ma and was partitioned into pure shear dominated domains that accommodated orogen-perpendicular shortening alternating with orogen-parallel high-strain domains that accommodated dextral transpression or bilateral extrusion. The synconvergent shortening of the TBU was terminated by a rapid gravity-driven collapse of the thickened lithosphere at textasciitilde346--337 Ma followed by, or partly simultaneous with, dextral strike-slip along the Baltica margin-parallel zones, driven by the westward movement of Gondwana from approximately 345 Ma onwards.
BibTeX:
@article{Hajná2012,
  author = {Hajná, Jaroslava and Žák, Jiří and Kachlík, Václav and Chadima, Martin},
  title = {Deciphering the Variscan tectonothermal overprint and deformation partitioning in the Cadomian basement of the Teplá–Barrandian unit, Bohemian Massif},
  journal = {International Journal of Earth Sciences},
  year = {2012},
  volume = {101},
  number = {7},
  pages = {1855--1873},
  url = {http://dx.doi.org/10.1007/s00531-012-0753-8 http://link.springer.com/10.1007/s00531-012-0753-8},
  doi = {http://dx.doi.org/10.1007/s00531-012-0753-8}
}
Hrouda, F. & Pokorný, J. (2012), "Modelling accuracy limits for frequency-dependent anisotropy of magnetic susceptibility of rocks and soils"; Studia Geophysica et Geodaetica, Vol. 56 (3) , pp. 789-802
Abstract: The frequency-dependent anisotropy of magnetic susceptibility (AMS) can be most easily determined through subtracting directional susceptibilities measured at two operating frequencies along each of the measuring directions and the differences subsequently processed using standard methods for AMS computation. The effect of the measurement precision on the accuracy of the determination of the frequency-dependent AMS is investigated through mathematical simulation of the measurement process using the statistical theory of measuring the AMS of rocks. The accuracy of the AMS determination is presented in terms of the errors in determining the principal susceptibilities and principal directions. By modelling the measuring errors, the limits are discovered for the investigation of the frequency-dependent AMS. The modelling shows extremely high requirements for measurement accuracy met by the most sensitive instruments, only.
BibTeX:
@article{Hrouda2011,
  author = {Hrouda, František and Pokorný, Jiří},
  title = {Modelling accuracy limits for frequency-dependent anisotropy of magnetic susceptibility of rocks and soils},
  journal = {Studia Geophysica et Geodaetica},
  year = {2012},
  volume = {56},
  number = {3},
  pages = {789--802},
  url = {http://link.springer.com/10.1007/s11200-011-9009-5},
  doi = {http://dx.doi.org/10.1007/s11200-011-9009-5}
}
Lisá, L., Lisý, P., Chadima, M. et al. (2012), "Microfacies description linked to the magnetic and non-magnetic proxy as a promising environmental tool: Case study from alluvial deposits of the Nile river"; Quaternary International, Vol. 266 , pp. 25-33
Abstract: Alluvial deposits within the Sabaloka Gorge and the Sixth Cataract, the Nile River, Sudan, represent a set of deposits with a high lithological variability. This is due to the geomorphology and short-time and intensive flood events resulting in aggradation and erosion of the alluvial zone. Human maintenance of the alluvial zone also plays a role. Therefore, these sediments seem to be ideal for a methodological case study to show how the lithological facies differ depending on the sedimentary dynamics of the river. Non-magnetic proxies together with TOC values depend on magnetic properties characterized by magnetic susceptibility and its frequency dependence. textcopyright 2011 Elsevier Ltd and INQUA.
BibTeX:
@article{Lisa2012,
  author = {Lisá, Lenka and Lisý, P and Chadima, Martin and Čejchan, P and Bajer, A and Cílek, Václav and Suková, L and Schnabl, Petr},
  title = {Microfacies description linked to the magnetic and non-magnetic proxy as a promising environmental tool: Case study from alluvial deposits of the Nile river},
  journal = {Quaternary International},
  year = {2012},
  volume = {266},
  pages = {25--33},
  doi = {http://dx.doi.org/10.1016/j.quaint.2011.05.030}
}
Mamtani, M. A., Chadima, M., de Wall, H. et al. (2012), "Rocks, fabrics and magnetic anisotropy: an introduction to the issue in honour of František Hrouda"; International Journal of Earth Sciences, Vol. 101 (3) , pp. 605-607
BibTeX:
@article{Mamtani2012,
  author = {Mamtani, Manish A and Chadima, Martin and de Wall, Helga and Greiling, Reinhard O},
  title = {Rocks, fabrics and magnetic anisotropy: an introduction to the issue in honour of František Hrouda},
  journal = {International Journal of Earth Sciences},
  year = {2012},
  volume = {101},
  number = {3},
  pages = {605--607},
  url = {http://dx.doi.org/10.1007/s00531-011-0733-4},
  doi = {http://dx.doi.org/10.1007/s00531-011-0733-4}
}
Martin-Hernandez, F., Guerrero-Suarez, S., Hrouda, F. et al. (2012), "MAGNETIC-ANISOTROPY OF ROCKS AND ITS APPLICATION IN GEOLOGY AND GEOPHYSICS"; Geophysical Surveys, Vol. 101 (1) , pp. 37-82
Abstract: Hematite is one of the most important carriers of remanent magnetization in natural samples. Its strong magnetocrystalline anisotropy makes it difficult to determine one single value for the magnetic anisotropy constant and other magnetic properties. In particular, the anisotropy of hematite within its basal plane is controversial because an assumed triaxial anisotropy compatible with the crystallographic structure has not always been detected. This study presents a comparative analysis of rock magnetic properties, compositional analysis and determination of the magnetic anisotropy constant. Different models with anisotropy constant within the basal plane ranging from 0 to 13 (J m(-3)) are considered in the evaluation of the factors that control the presence or absence of a triaxial anisotropy. A linear relationship between saturation magnetization (M-s) and coercitivity (B-c) in measurements at increasing temperatures is observed in samples where anisotropy is either uniaxial or biaxial while those with significant triaxial anisotropies have a power-law relationship between M-s and B-c.
BibTeX:
@article{Martin-Hernandez2012,
  author = {Martin-Hernandez, F and Guerrero-Suarez, S and Hrouda, František and Trindade, R I F and Nguema, T Mintsa Mi and Bouchez, J L and Benz, Manuel and Search, Home and Journals, Collections and Contact, About and Iopscience, My and Address, I P and Eccnron, A and Beunrnlo, Jrr F and Parma, Jan and Hirt, Ann M and Usdowski, E and Frankel, Richard B and Bazylinskib, Dennis A and Schülerb, Dirk and Dunlop, David J and Özdemir, Özden and Rancourt, Denis G and Zablotskii, V and Yurchenko, V and Kamysa, Y and Chelombetskaya, M and Biedermann, Andrea Regina and Jackson, Andrew and Pettke, Thomas and Ferré, Eric C and Jia, Rong-fen and Peng, Xien-zi and Grygar, Tomáš and Bezdíčka, Petr and Dědeček, Jiří and Petrovský, Eduard and Schneeweiss, Oldřich and Parry, W T and Downey, L M and Larrasoan, Juan C and Aubourg, Charles and Boullier, Anne-marie and Lee, Teh-quei and Evans, Mark and Chen, Yi-ming and Pare, Josep M and Pluijm, Ben A Van Der and Putnis, R J Harrison A and Kalczynski, Michael J and Gates, Alexander E and Bowles, Julie and Jackson, Michael J Mike Michael and Chen, Amy and Solheid, Peter and Banerjee, Subir K and Moskowitz, Bruce M and Bowles, Julie and Rochette, Pierre and Fillion, Gérard and Dekkers, Mark J and Aix-marseille, Université and Lattard, Dominique and Engelmann, Ralf and Kontny, Agnes and Sauerzapf, Ursula and Koch, A Kontny Á A B Woodland Á M and O, Mg Sio Fe and Henry, Bernard and Borradaile, Graham J and Search, Home and Journals, Collections and Contact, About and Iopscience, My and Address, I P and Moskowitz, Bruce M and Jackson, Michael J Mike Michael and Kissel, Catherine and Muxworthy, A R and Borradaile, Graham J and Werner, Tomasz and Thrace, From West and Anagnostopoulos, T and Calamiotou, M and Lagroix, France and Borradaile, Graham J and Sigamony, A and Cui, Z and Liu, Qingsong and Etsell, T H and Moskowitz, Bruce M and Frankel, Richard B and Flanders, P and Blakemore, R P and Schwartz, B B and Santana, G P and Abris, D F and Santana, D P and Yan, Lei and Zhang, Shuang and Chen, Peng and Liu, Hetao and Yin, Huanhuan and Li, Hongyu and Frank, Ute and Nowaczyk, Norbert R and Geomagnetism, G J I and Dearing, John A and Dearing, John A and Weibel, R and Friis, H and Prud, Michel and Krukowski, Stanley T and Radhakrishnamurty, C and Subbarao, K V and Society, Geological and Special, London and Alvarez, Costanzo and Bol, Simon and Aldana, Milagrosa and Bol, Simon and Martõ, Â and Hirt, Ann M and Ye, Z-g and Janner, A-m and Schmid, H and Gegensatz, Im and Partikelgr, Die and Detail, Im and Zeit, Die and Liu, Qingsong and Deng, Chenglong and Yu, Yongjae and Jackson, Michael J Mike Michael and Banerjee, Subir K and Zhu, Rixiang and Li, Gejing and Peacor, Donald R and Essene, Eric J and Dunlop, David J and Borradaile, Graham J and Lagroix, France and Widdrat, Marc},
  title = {MAGNETIC-ANISOTROPY OF ROCKS AND ITS APPLICATION IN GEOLOGY AND GEOPHYSICS},
  journal = {Geophysical Surveys},
  year = {2012},
  volume = {101},
  number = {1},
  pages = {37--82},
  url = {http://dx.doi.org/10.1016/j.micres.2012.04.002%5Cnhttp://dx.doi.org/10.1016/j.oregeorev.2014.02.007%5Cn%3CGo to ISI%3E://WOS:A1982NK85200002%5Cn%3CGo to ISI%3E://WOS:000304186300006},
  doi = {http://dx.doi.org/10.1007/bf01450244}
}
Chadima, M. & Hrouda, F. (2011), "Discrimination of normal and inverse magnetic fabrics in dikes of the Ceske stredohori Mts. based on a combined study of AMS, AMR, field-dependent AMS and frequency-dependent AMS"; AGU Fall Meeting Abstracts,
BibTeX:
@article{2011AGUFMGP14A..06C,
  author = {Chadima, Martin and Hrouda, František},
  title = {Discrimination of normal and inverse magnetic fabrics in dikes of the Ceske stredohori Mts. based on a combined study of AMS, AMR, field-dependent AMS and frequency-dependent AMS},
  journal = {AGU Fall Meeting Abstracts},
  year = {2011}
}
Chadima, M., Pokorný, J. & Dušek, M. (2011), "Rema6W–MSWindows Software for Controlling JR-6 Series Spinner Magnetometers"; , The Earth's Magnetic Interior , pp. 303-309, Springer Netherlands
BibTeX:
@inbook{Chadima2011,
  author = {Chadima, Martin and Pokorný, Jiří and Dušek, Miroslav},
  title = {Rema6W–MSWindows Software for Controlling JR-6 Series Spinner Magnetometers},
  booktitle = {The Earth's Magnetic Interior},
  publisher = {Springer Netherlands},
  year = {2011},
  pages = {303--309},
  url = {http://dx.doi.org/10.1007/978-94-007-0323-0_21},
  doi = {http://dx.doi.org/10.1007/978-94-007-0323-0_21}
}
Chlupáčová, M., Hrouda, F., Nižňanský, D. et al. (2011), "Frequency-dependent susceptibility and other magnetic properties of Celtic and Mediaeval graphitic pottery from Bohemia: an introductory study"; Studia Geophysica et Geodaetica, Vol. 56 (3) , pp. 803-825
Abstract: Frequency-dependent magnetic susceptibility, its anisotropy (AMS), its temperature variation, natural remanent magnetization and time-dependent isothermal remanent magnetization as well as Mössbauer spectroscopy of a small collection of Celtic and Mediaeval graphitic pottery from Southern Bohemia were investigated. The mineral composition of the pottery is dominated by fragments of quartz, accompanied mainly by various silicates from granitoids and paragneisses, or by calcite, within the plastic component being probably illite but also graphite. No ferrimagnetic minerals were found in optical microscope, among Fe-oxides only limonite was observed, even though the bulk susceptibility of the pottery varies in the orders of 10−4 to 10−2 [SI]. This may indicate presence of ferromagnetic particles in the ultrafine (superparamagnetic, SP) state, which is confirmed by frequency-dependent susceptibility ranging from 3% to almost 16%. The low temperature susceptibility vs. temperature curves are only moderately sloped, showing the Verwey transition only in one case. The high temperature curves mostly show presence of two magnetic phases, maghemite and magnetite. Cooling curves show distinctly lower susceptibilities than the heating curves indicating instability of the assemblage of ferrimagnetic minerals, particularly in temperatures slightly under 700 textdegreeC. Mössbauer spectroscopy confirmed the results of the frequency-dependent susceptibility, showing the increase of ferrimagnetic sextets in the spectra measured at 4.2K, likely indicating maghemite as the distinct ferrimagnetic phase. The frequency-dependent AMS indicates preferred orientation of SP1,16 particles, coaxiality between SP1,16 grain AMS and whole specimen AMS indicate that all grains, ultrafine and coarser ones, were oriented by the same process, i.e. copying the pottery structure created during wheel-turning.
BibTeX:
@article{Chlupáčová2011,
  author = {Chlupáčová, Marta and Hrouda, František and Nižňanský, Daniel and Procházka, Václav and Petáková, Zdevnka and Laufek, František},
  title = {Frequency-dependent susceptibility and other magnetic properties of Celtic and Mediaeval graphitic pottery from Bohemia: an introductory study},
  journal = {Studia Geophysica et Geodaetica},
  year = {2011},
  volume = {56},
  number = {3},
  pages = {803--825},
  url = {http://dx.doi.org/10.1007/s11200-011-9011-y},
  doi = {http://dx.doi.org/10.1007/s11200-011-9011-y}
}
Hrouda, F. (2011), "Models of frequency-dependent susceptibility of rocks and soils revisited and broadened"; Geophysical Journal International, Vol. 187 (3) , pp. 1259-1269, Blackwell Publishing Ltd
Abstract: Mathematical models of the frequency-dependent susceptibility in rocks, soils and environmental materials have been adapted to measurements performed with multiple operating frequencies (465, 976, 3904, 4650, 15 616, 100 000 and 250 000 Hz) on the basis of log-normal volume distribution of magnetic particles. The XFD parameter depends, in addition to the amount of SP particles, also on the operating frequencies, whose values should be therefore also presented. The model curves of the XFD parameter versus arithmetical mean ($) of the logarithms of grain volume are roughly bell-like shaped. The width and peak position of these curves is controlled by mean and standard deviation of the logarithmic volume distribution. Magnetic susceptibility contributions from paramagnetic minerals, and from ferrimagnetic particles not belonging to a unimodal SP/SD volume distribution, tend to decrease the XFD parameter. Therefore, low XFD values do not therefore necessarily indicate low amount of SP particles, but can also be indicative of the presence of the paramagnetic fraction. A new parameter XR is introduced based on susceptibility measurements at three operating frequencies; it is insensitive to dia- and paramagnetic fractions and helps us to differentiate between wide and narrow size distributions of ferromagnetic particles. A new XFB parameter is introduced that originates through normalizing the XFD parameter by the difference of natural logarithms of operating frequencies and related to the decade difference between the frequencies. It is convenient for comparison of the Bartington MS-2 Susceptibility Meter data with the MFK1-FA Kappabridge data.
BibTeX:
@article{GJI:GJI5227,
  author = {Hrouda, František},
  title = {Models of frequency-dependent susceptibility of rocks and soils revisited and broadened},
  journal = {Geophysical Journal International},
  publisher = {Blackwell Publishing Ltd},
  year = {2011},
  volume = {187},
  number = {3},
  pages = {1259--1269},
  url = {http://dx.doi.org/10.1111/j.1365-246X.2011.05227.x},
  doi = {http://dx.doi.org/10.1111/j.1365-246X.2011.05227.x}
}
Hrouda, F. & Pokorný, J. (2011), "Extremely high demands for measurement accuracy in precise determination of frequency-dependent magnetic susceptibility of rocks and soils"; Studia Geophysica et Geodaetica, Vol. 55 (4) , pp. 667-681
Abstract: Frequency-dependent magnetic susceptibility, which is an important tool for environmental and palaeoclimatologic research, is usually relatively low, mostly less than 15% of the low frequency value and there is a demand for high precision of its measurement. The accuracy required for the susceptibility measurement at individual operating frequencies for precise determination of the parameter characterizing the frequency-dependent susceptibility was investigated theoretically and also experimentally through repeated measurement of artificial specimens and sediments of a loess/palaeosol sequence using the MFK1 Kappabridge. It was found that the variation in the frequency-dependence in the order of 1% is well reproducible and the measurements can be interpreted in terms of magnetic granulometry even in weakly magnetic materials.
BibTeX:
@article{Hrouda2011,
  author = {Hrouda, František and Pokorný, Jiří},
  title = {Extremely high demands for measurement accuracy in precise determination of frequency-dependent magnetic susceptibility of rocks and soils},
  journal = {Studia Geophysica et Geodaetica},
  year = {2011},
  volume = {55},
  number = {4},
  pages = {667--681},
  url = {http://dx.doi.org/10.1007/s11200-010-0079-6},
  doi = {http://dx.doi.org/10.1007/s11200-010-0079-6}
}
Hrouda, F. (2011), "Anisotropy of Magnetic Susceptibility in Variable Low-Fields: A Review"; , The Earth's Magnetic Interior , pp. 281-292, Springer Netherlands
Abstract: Theory of the Anisotropy of Magnetic Susceptibility (AMS) assumes field-independent rock susceptibility in the low fields used by common AMS meters. This is valid for rocks whose AMS is carried by diamagnetic and paramagnetic minerals and also by pure magnetite, while rocks with pyrrhotite, hematite or titanomagnetite may show significant variation of susceptibility in common measuring fields. Consequently, the use of the contemporary AMS theory is in principle incorrect in these cases. Fortunately, it has been shown by practical measurements and mathematical modelling of the measuring process that the variations of the principal directions and of the AMS ellipsoid shape with field are very weak, which is important in most geological applications. The degree of AMS, however, may show conspicuous variation with field and, if one wants to make precise quantitative fabric interpretation, it is desirable to work with the AMS of the field-independent component. Three methods exist for simultaneous determination of the field-independent and field-dependent AMS components, all based on standard AMS measurement in variable fields within the Rayleigh Law range. The field-dependence of the AMS can be used in solving some geological problems. For example, in volcanic and dyke rocks with inverse magnetic fabric, one can decide whether this inversion has geological (special flow regime of lava) or physical (SD vs. MD grains) causes. In rocks consisting of two magnetic fractions, one with field-independent susceptibility (magnetite, paramagnetic minerals) and the other possessing the field-dependent susceptibility (titanomagnetite, hematite, pyrrhotite), one can separate the AMS of the latter fraction and in favourable cases also of the former fraction.
BibTeX:
@inbook{Hrouda2011,
  author = {Hrouda, František},
  title = {Anisotropy of Magnetic Susceptibility in Variable Low-Fields: A Review},
  booktitle = {The Earth's Magnetic Interior},
  publisher = {Springer Netherlands},
  year = {2011},
  pages = {281--292},
  url = {http://www.springerlink.com/index/10.1007/978-94-007-0323-0_19},
  doi = {http://dx.doi.org/10.1007/978-94-007-0323-0_19}
}
Mamtani, M. A., Piazolo, S., Greiling, R. O. et al. (2011), "Process of magnetite fabric development during granite deformation"; Earth and Planetary Science Letters, Vol. 308 (1-2) , pp. 77-89
Abstract: This study evaluates the fabric defined by magnetite grains in a syntectonically deformed granite and deciphers the processes that led to magnetite fabric development. Anisotropy of anhysteretic remanence magnetization (AARM) analysis is performed in samples taken from different parts of the granite to establish that the magnetite grains define a fabric. Along with microstructural studies, the AARM data help conclude that this fabric is on account of shape preferred orientation (SPO) of the magnetite grains. The intensity of magnetite fabric (degree of anisotropy of the AARM ellipsoid) is higher in the southern parts as compared to the north, which is inferred to indicate a strain gradient. Electron back scattered diffraction (EBSD) analyses of magnetite grains were performed to determine if there are intracrystalline deformation features that could have influenced magnetite shape and SPO, and thus AARM data. Detailed crystallographic orientation data coupled with orientation contrast imaging did not reveal any subgrains and/or significant variations in crystallographic orientations within magnetite grains. Instead, grains exhibit fractures and are in places associated with quartz pressure fringes. Hence, neither the SPO nor the variation in the magnetite fabric intensity in the granite can be attributed to intracrystalline deformation of magnetite by dislocation creep. It is concluded that the magnetite grains were rheologically rigid and there was relative movement between the magnetite and the matrix minerals (quartz, feldspar and biotite). These matrix minerals actually define the fabric attractor and the magnetite grains passively rotated to align with it. Thus it is demonstrated that the magnetite fabric in the granite stems from rigid body movement rather than dislocation creep.
BibTeX:
@article{Mamtani2011,
  author = {Mamtani, Manish A and Piazolo, Sandra and Greiling, Reinhard O and Kontny, Agnes and Hrouda, František},
  title = {Process of magnetite fabric development during granite deformation},
  journal = {Earth and Planetary Science Letters},
  year = {2011},
  volume = {308},
  number = {1-2},
  pages = {77--89},
  url = {http://www.sciencedirect.com/science/article/pii/S0012821X11003165},
  doi = {http://dx.doi.org/10.1016/j.epsl.2011.05.033}
}
Pokorný, J., Pokorný, P., Suza, P. et al. (2011), "A Multi-Function Kappabridge for High Precision Measurement of the AMS and the Variations of Magnetic Susceptibility with Field, Temperature and Frequency"; , The Earth's Magnetic Interior , pp. 293-301, Springer Netherlands
Abstract: A new MFK1-FA Kappabridge is introduced that precisely measures the magnetic susceptibility of rocks and the anisotropy of susceptibility. The instrument has the following features: separation of the in-phase (real) and out-of-phase (imaginary) components, auto-ranging and auto-zeroing, automated measurement of the field variation of the bulk susceptibility, AMS measurements using the spinning specimen method, built-in circuitry for controlling the non-magnetic furnace (CS-4) and cryostat (CS-L), full instrument control by an external computer, sophisticated hardware and software diagnostics. Examples are shown to illustrate the capability of the instrument for rock magnetic and palaeomagnetic research.
BibTeX:
@inbook{Pokorný2011,
  author = {Pokorný, Jiří and Pokorný, Petr and Suza, Petr and Hrouda, František},
  title = {A Multi-Function Kappabridge for High Precision Measurement of the AMS and the Variations of Magnetic Susceptibility with Field, Temperature and Frequency},
  booktitle = {The Earth's Magnetic Interior},
  publisher = {Springer Netherlands},
  year = {2011},
  pages = {293--301},
  url = {http://www.springerlink.com/index/10.1007/978-94-007-0323-0_20},
  doi = {http://dx.doi.org/10.1007/978-94-007-0323-0_20}
}
Chlupáčová, M. (2010), "Magnetomineralogy of the cordierite gneiss from the magnetic anomaly at Humpolec, Bohemian Moldanubicum (Czech Republic)"; Studia Geophysica et Geodaetica, Vol. 54 (1) , pp. 95-120
Abstract: Magnetic properties as well as the magnetomineralogy were investigated in rocks underlying a 7 km long aeromagnetic anomaly situated in the Moldanubian crystalline unit of the Bohemian Massif. The anomaly is caused by highly magnetic cordierite gneiss forming a stripe of NE - SW direction east of the town of Humpolec, eastern Bohemia. Magnetic susceptibility and its anisotropy (AMS), natural remanent magnetization, field and temperature variations of susceptibility were measured. Optical study of thin sections, electron microprobe and Mossbauer studies were also used to reveal the carrier of the high susceptibility and the high NRM. There appear to be two major generations of Fe-Ti oxides: older hematite with ilmenite exsolutions (Ti-hematite) which is the dominant remanence phase, and younger magnetite, the dominant susceptibility phase, usually associated with rutile.
BibTeX:
@article{Chlupacova2010,
  author = {Chlupáčová, Marta},
  title = {Magnetomineralogy of the cordierite gneiss from the magnetic anomaly at Humpolec, Bohemian Moldanubicum (Czech Republic)},
  journal = {Studia Geophysica et Geodaetica},
  year = {2010},
  volume = {54},
  number = {1},
  pages = {95--120},
  url = {http://link.springer.com/article/10.1007/s11200-010-0005-y}
}
Schnabl, P., Novák, J. K., Cajz, V. et al. (2010), "Magnetic properties of high-Ti basaltic rocks from the Krušné hory/Erzgebirge MTS. (Bohemia/Saxony), and their relation to mineral chemistry"; Studia Geophysica et Geodaetica, Vol. 54 (1) , pp. 77-94
Abstract: Abstract This study provides new thermomagnetic and petrographic data on specific basaltic rock association from the broader vicinity of the Loučná-Oberwiesenthal volcanic centre, western Bohemia/Saxony. Two types of volcanic rocks were recognized there: (i) high-Ti types (3.5–5.2 wt% TiO2) represented by (mela)nephelinite s.s., and sporadically present (ii) medium-Ti types (2.5–3.5 wt% TiO2) of olivine nephelinite, nepheline basanite and phonotephrite compositions. In order to examine the rock-magnetic behaviour, they were studied for their variations in the Curie temperature (TC) and field-dependent susceptibility, spinel group minerals, chemistry and petrology. Magnetic susceptibility of ulvöspinel-rich titanomagnetite, as a dominant magnetic carrier, depends on the amplitude of measured magnetic field, whereas pure magnetite is field-independent. Field dependence parameter kHD of the studied basaltic rocks ranges from 0.8 to 18.7%, TiO2 contents in titanomagnetite range from 12.7 to 20.1 wt.%. TiO2 content in titanomagnetite does not correlate with whole-rock TiO2 content (2.8 to 5.6 wt.%). The content of substituted titanium in the sublattice of magnetite is also sensitively reflected in the Curie temperature, ranging from 200 to 580°C. The spinel group minerals are designated as titanomagnetite with the dominance of ulvöspinel, magnetite and magnesioferrite components, or titanomagnetite with the magnetite, ulvöspinel and magnesioferrite components. Only two samples are characterized by a significant presence of Cr-spinel and magnesiochromite components forming cores of titanomagnetites. The titanomagnetite-bearing rocks in the studied area, likewise the low- to medium-Ti basaltic rocks from the České středohoří Mts., provide similar thermomagnetic curves.
BibTeX:
@article{citeulike:6886535,
  author = {Schnabl, Petr and Novák, Jiří K and Cajz, Vladimír and Lang, Miloš and Balogh, Kadosa and Pécskay, Zoltan and Chadima, Martin and Šlechta, Stanislav and Kohout, Tomáš and Pruner, Petr and Ulrych, Jaromír},
  title = {Magnetic properties of high-Ti basaltic rocks from the Krušné hory/Erzgebirge MTS. (Bohemia/Saxony), and their relation to mineral chemistry},
  journal = {Studia Geophysica et Geodaetica},
  year = {2010},
  volume = {54},
  number = {1},
  pages = {77--94},
  url = {http://link.springer.com/10.1007/s11200-010-0004-z},
  doi = {http://dx.doi.org/10.1007/s11200-010-0004-z}
}
Hajná, J., Žák, J., Kachlík, Vá. et al. (2010), "Subduction-driven shortening and differential exhumation in a Cadomian accretionary wedge: The Teplá–Barrandian unit, Bohemian Massif"; Precambrian Research, Vol. 176 (1-4) , pp. 27-45
Abstract: The Teplá–Barrandian unit (TBU) of Central Europe's Bohemian Massif exposes perhaps the best preserved fragment of an accretionary wedge in the Avalonian–Cadomian belt, which developed along the northern active margin of Gondwana during Late Neoproterozoic. In the central TBU, three NE–SW-trending lithotectonic units (Domains 1–3) separated by antithetic brittle faults differ in lithology, style and intensity of deformation, magnetic fabric (AMS), and degree of Cadomian regional metamorphism. The flysch-like Domain 1 to the NW is the most outboard (trenchward) unit which has never been significantly buried and experienced only weak deformation and folding. The central, mélange-like Domain 2 is characterized by heterogenous intense deformation developed under lower greenschist facies conditions, and was thrust NW over Domain 1 along a SE-dipping fault. To the SE, the most inboard (arcward) Domain 3 is lithologically monotonous (dominated by graywackes and slates), was buried to depths corresponding up to the lower greenschist facies conditions, where it was overprinted by a pervasive SE-dipping cleavage and then was exhumed along a major NW-dipping normal fault. We interpret these domains to represent allochtonous tectonic slices that were differentially buried and then exhumed from various depths within the accretionary wedge during Cadomian subduction. The NW-directed thrusting of Domain 2 over Domain 1 may have been caused by accretion at the wedge front, whereas the SE-dipping cleavage and SE-side-up exhumation of Domain 3 may record inclined pervasive shortening during tectonic underplating and subsequent horizontal extension of the rear of the wedge. The boundary faults were later reactivated during Cambro–Ordovician extension and Variscan compression. Compared to related terranes of the Cadomian belt, the TBU lacks exposed continental basement, evidence for regional strike-slip shearing, and extensive backarc magmatism and LP–HT metamorphism, which could be interpreted to reflect flat-slab Cadomian subduction. This, in turn, suggests that Cadomian accretionary wedges developed in a manner identical to those of modern settings, elevating the TBU to a key position for understanding the style, kinematics, and timing of accretionary processes along the Avalonian–Cadomian belt.
BibTeX:
@article{Hajna2010,
  author = {Hajná, Jaroslava and Žák, Jiří and Kachlík, Václav and Chadima, Martin},
  title = {Subduction-driven shortening and differential exhumation in a Cadomian accretionary wedge: The Teplá–Barrandian unit, Bohemian Massif},
  journal = {Precambrian Research},
  year = {2010},
  volume = {176},
  number = {1-4},
  pages = {27--45},
  url = {http://www.sciencedirect.com/science/article/pii/S0301926809002162},
  doi = {http://dx.doi.org/10.1016/j.precamres.2009.10.009}
}
Hrouda, F. (2010), "Modelling relationship between bulk susceptibility and AMS in rocks consisting of two magnetic fractions represented by ferromagnetic and paramagnetic minerals — Implications for understanding magnetic fabrics in deformed rocks"; Journal of the Geological Society of India, Vol. 75 (1) , pp. 254-266
Abstract: Measurement of Anisotropy of Magnetic Susceptibility (AMS) has become an important tool for Structural Geological analysis in the past few decades. In the past, AMS data have been used for petrofabric analysis of deformed rocks as well as for gauging strain. However, the AMS of some rocks can be carried by both ferromagnetic and paramagnetic minerals. Separating effects of these mineral groups on the rock's AMS is difficult because of expensive and commercially less available instrumentation. On the other hand, instrumentation is available in most rock magnetic and palaeomagnetic laboratories for resolving bulk susceptibility into ferromagnetic and paramagnetic components. Mathematical modelling was made of the relationship between bulk susceptibility and AMS. If the contribution of the ferromagnetic or the paramagnetic fraction to the rock susceptibility is dominant (let us say higher than 80%), the resultant AMS is relatively near to the AMS of the dominating fraction in all aspects, the degree of AMS, shape parameter and orientation of principal susceptibilities. In the interpretation of the AMS of rocks with dominating one fraction, the resolution of the AMS into paramagnetic and ferromagnetic components is not necessary, the resolution of bulk susceptibility into components is sufficient that can be made using the instrumentation available in most rock magnetic and palaeomagnetic laboratories.
BibTeX:
@article{Hrouda2010,
  author = {Hrouda, František},
  title = {Modelling relationship between bulk susceptibility and AMS in rocks consisting of two magnetic fractions represented by ferromagnetic and paramagnetic minerals — Implications for understanding magnetic fabrics in deformed rocks},
  journal = {Journal of the Geological Society of India},
  year = {2010},
  volume = {75},
  number = {1},
  pages = {254--266},
  url = {http://link.springer.com/10.1007/s12594-010-0013-0},
  doi = {http://dx.doi.org/10.1007/s12594-010-0013-0}
}
Procházka, Vá., Chlupáčová, M., Nižňanský, D. et al. (2010), "Magnetomineralogy of the cordierite gneiss from the magnetic anomaly at Humpolec, Bohemian Moldanubicum (Czech Republic)"; Studia Geophysica et Geodaetica, Vol. 54 (1) , pp. 95-120
Abstract: Magnetic properties as well as the magnetomineralogy were investigated in rocks underlying a 7 km long aeromagnetic anomaly situated in the Moldanubian crystalline unit of the Bohemian Massif. The anomaly is caused by highly magnetic cordierite gneiss forming a stripe of NE - SW direction east of the town of Humpolec, eastern Bohemia. Magnetic susceptibility and its anisotropy (AMS), natural remanent magnetization, field and temperature variations of susceptibility were measured. Optical study of thin sections, electron microprobe and Mossbauer studies were also used to reveal the carrier of the high susceptibility and the high NRM. There appear to be two major generations of Fe-Ti oxides: older hematite with ilmenite exsolutions (Ti-hematite) which is the dominant remanence phase, and younger magnetite, the dominant susceptibility phase, usually associated with rutile. This indicates a reaction Hematite + Ilmenite -> Magnetite + + Rutile; the trace elements in magnetite, as well as texture and morphology of the oxide grains support this assertion. An additional minor portion of maghemite is revealed by Mossbauer and thermomagnetic results. The Ti-hematite belongs to the oldest mineral assemblage in the rock, despite its anhedral morphology. Inclusions in Ti-hematite, among which corundum and abundant paragonite occur, record a strongly peraluminous and probably disequilibrium association during the crystallization of the Ti-hematite.
BibTeX:
@article{ISI:000275695600005,
  author = {Procházka, Václav and Chlupáčová, Marta and Nižňanský, Daniel and Hrouda, František and Uher, Pavel and Rajlich, Petr},
  title = {Magnetomineralogy of the cordierite gneiss from the magnetic anomaly at Humpolec, Bohemian Moldanubicum (Czech Republic)},
  journal = {Studia Geophysica et Geodaetica},
  year = {2010},
  volume = {54},
  number = {1},
  pages = {95--120},
  doi = {http://dx.doi.org/10.1007/s11200-010-0005-y}
}
Kratinová, Z., Ježek, J., Schulmann, K. et al. (2010), "Noncoaxial K-feldspar and AMS subfabrics in the Land's End granite, Cornwall: Evidence of magmatic fabric decoupling during late deformation and matrix crystallization"; Journal of Geophysical Research, Vol. 115 (B9) , pp. B09104
Abstract: A comparative study of the anisotropy of magnetic susceptibility (AMS) and K-feldspar phenocryst fabrics in the Land's End granite demonstrates that the AMS fabric predominantly reflects late magmatic deformation. Tensor analysis of the K-feldspar fabric shows a complex pattern, characterized by meter-scale variations in orientation, symmetry, and intensity, mainly related to heterogeneous flow of the phenocryst-rich magma during emplacement. In contrast, the AMS fabric is predominantly homogenous, subhorizontal, and oblate, and is stable at the pluton scale. Quantitative microstructural analysis suggests that the AMS fabric is controlled by deformation of the partially crystallized matrix, resulting from the combined effects of late internal adjustment within the pluton and regional deformation. A general model of fabric development associated with a vertical pure-shear overprint on a variable vertical fabric is evaluated by numerical modeling. The study demonstrates how the memory of different fabric elements may be dependent upon their grain size, crystallization sequence, and recorded previous strain.
BibTeX:
@article{Kratinova2010,
  author = {Kratinová, Zuzana and Ježek, Josef and Schulmann, Karel and Hrouda, František and Shail, Robin K. and Lexa, Ondrej},
  title = {Noncoaxial K-feldspar and AMS subfabrics in the Land's End granite, Cornwall: Evidence of magmatic fabric decoupling during late deformation and matrix crystallization},
  journal = {Journal of Geophysical Research},
  year = {2010},
  volume = {115},
  number = {B9},
  pages = {B09104},
  url = {http://doi.wiley.com/10.1029/2009JB006714},
  doi = {http://dx.doi.org/10.1029/2009JB006714}
}
Žák, J., Hrouda, F. & Holub, F. V. (2010), "Plane-confined magnetic lineations in mingled mafic and felsic magmas, the Sázava pluton, Bohemian Massif"; Journal of Volcanology and Geothermal Research, Vol. 190 (3-4) , pp. 312-324
Abstract: Multiple magnetic lineations were revealed using the anisotropy of magnetic susceptibility (AMS) and anisotropy of magnetic remanence (AMR) methods in a domain of mafic–felsic magma mingling at the northwestern margin of the Sázava pluton, Central Bohemian Plutonic Complex, Bohemian Massif. Gabbrodioritic enclave swarms and sheets are steeply oriented and exhibit magnetic lineations plunging at steep to moderate angles (mostly 40–70°) whereas in their tonalitic host lineations plunge from vertical to horizontal angles, but mostly less than 40°. The magnetic lineations in both rock types spread along a $NNE-SSW steep plane that could be simplified as representing an “average” margin-parallel magmatic foliation in the pluton concordant with an “average” regional cleavage in the wall-rock. The plane-confined lineations are interpreted as having recorded the heterogeneous superposition of two processes: (1) vertical stretching during emplacement and magma mingling which left behind the steep lineations; and (2) regional tectonic stretching, which progressively rotated the mineral grains in rheologically weaker domains (chiefly in the host tonalite) to form the sub-horizontal lineation. The average foliation bearing the multiple lineations is interpreted as a composite foliation that recorded both margin-perpendicular shortening during emplacement, overprinted by coaxial regional tectonic shortening. This example reaffirms that (1) magmatic fabrics in crystallizing magmas can record accumulated strain resulting from both emplacement and regional tectonic deformation; and that (2) separating magmatic (and also magnetic) fabrics related exclusively to the internal chamber processes from fabrics caused by regional tectonic deformation is problematic or even impossible in cases where composite fabrics are recognized.
BibTeX:
@article{Zak2010,
  author = {Žák, Jiří and Hrouda, František and Holub, František V.},
  title = {Plane-confined magnetic lineations in mingled mafic and felsic magmas, the Sázava pluton, Bohemian Massif},
  journal = {Journal of Volcanology and Geothermal Research},
  year = {2010},
  volume = {190},
  number = {3-4},
  pages = {312--324},
  url = {http://www.sciencedirect.com/science/article/pii/S0377027309004612},
  doi = {http://dx.doi.org/10.1016/j.jvolgeores.2009.12.002}
}
Chadima, M., Cajz, V. & Týcová, P. (2009), "On the interpretation of normal and inverse magnetic fabric in dikes: Examples from the Eger Graben, NW Bohemian Massif"; Tectonophysics, Vol. 466 (1-2) , pp. 47-63
Abstract: Recent studies of igneous rocks indicate that the predominant occurrence of normal/inverse fabric in dikes may either reflect the presence of multi-domain (MD)/single-domain (SD) grains or it may result from different orientation mechanisms of magnetic minerals in magmas of different viscosities. The ambiguity in physical vs. geological cause of normal/inverse magnetic fabric must be answered before any successful geological interpretation of magnetic fabric can be made. In order to address this problem, we studied magnetic fabric of selected dikes associated with the SW–NE trending Eger Graben (NW Bohemian Massif). The studied area offered very extensive collection of rock types: basanite, bostonite, camptonite, tinguaite, and trachybasalt. Magnetic susceptibility varies according to rock type and reflects the relative contents of magnetic minerals. In most cases, titanomagnetite with variable Ti content was identified as main magnetic carrier. The degree of anisotropy is relatively low, in most cases less than 10%, the shape of anisotropy ellipsoid ranges from slightly prolate to neutral and oblate. Several different types of magnetic fabric (using anisotropy of low-field magnetic susceptibility, AMS) were observed in studied dikes: so-called normal and inverse magnetic fabrics and anomalous magnetic fabric. Comparing all studied sites it seems that the type of magnetic fabric is lithology-dependent. Normal magnetic fabric with magnetic foliations and subhorizontal magnetic lineations both parallel to the dike margins was found in bostonite and trachybasalt dikes. Inverse magnetic fabric with magnetic lineations and magnetic foliations perpendicular to the dike margins was found in camptonite dikes. Anisotropy of anhysteretic remanent magnetization (AMR) indicate that the observed inverse magnetic fabric may be caused by the presence of SD magnetic grains; AMR fabric being normal with respect to dike margins. In contrast to that no single-domain particles were revealed using frequency dependence and anhysteretic susceptibility measurements. The AMS measured in variable weak magnetic fields is field dependent for camptonite dike and field independent for other rock types, i.e. bostonite, basanite, tinguaite, and trachybasalt. For further flow direction and tectonic interpretations of magnetic fabric in dikes it is suggested to use preferably the AMR fabric (at least for dikes which demonstrate significant field dependence of AMS) as it reflects the ‘true' rock fabric more accurately than AMS fabric.
BibTeX:
@article{Chadima2009,
  author = {Chadima, Martin and Cajz, Vladimír and Týcová, Patricie},
  title = {On the interpretation of normal and inverse magnetic fabric in dikes: Examples from the Eger Graben, NW Bohemian Massif},
  journal = {Tectonophysics},
  year = {2009},
  volume = {466},
  number = {1-2},
  pages = {47--63},
  url = {http://www.sciencedirect.com/science/article/pii/S0040195108004290},
  doi = {http://dx.doi.org/10.1016/j.tecto.2008.09.005}
}
Cifelli, F., Mattei, M., Chadima, M. et al. (2009), "The magnetic fabric in “undeformed clays”: AMS and neutron texture analyses from the Rif Chain (Morocco)"; Tectonophysics, Vol. 466 (1-2) , pp. 79-88
Abstract: In this study we analyse the magnetic and mineral fabric of clay sediments that appear homogeneous and not deformed at the outcrop scale. We integrate low-field, high-field and low-temperature AMS analyses with neutron diffraction pole figures analysis as an alternative approach to studying the deformation mechanisms that drive the development of the magnetic lineation in these sediments. The studied sediments are Neogene claystones sampled from the Rif Chain (Morocco). High-field AMS measurements carried out on a large number of samples show that the relative percentage of the ferrimagnetic contribution is not significant (generally <5%) and paramagnetic contribution prevails (generally >95%). The principal axes of both components coincide with those of the low-field AMS at room and low temperatures. These results indicate that the magnetic anisotropy of the studied samples is predominantly carried by the paramagnetic phyllosilicates, i.e. chlorite, as deduced by X-ray diffraction. Neutron texture analysis confirms that the different AMS ellipsoids obtained with different magnetic methods reflect the spatial distribution of the basal planes of chlorite, demonstrating the great potential of the AMS to determine the mineral orientation fabric. The combination of these different approaches enables to establish a more accurate qualitative and quantitative correlation between the chlorite fabric and magnetic anisotropy and yields valuable information about the tectonic meaning of the magnetic fabric.
BibTeX:
@article{Cifelli2009,
  author = {Cifelli, Francesca and Mattei, M and Chadima, Martin and Lenser, S and Hirt, A.M.},
  title = {The magnetic fabric in “undeformed clays”: AMS and neutron texture analyses from the Rif Chain (Morocco)},
  journal = {Tectonophysics},
  year = {2009},
  volume = {466},
  number = {1-2},
  pages = {79--88},
  url = {http://www.sciencedirect.com/science/article/pii/S0040195108003806 http://linkinghub.elsevier.com/retrieve/pii/S0040195108003806},
  doi = {http://dx.doi.org/10.1016/j.tecto.2008.08.008}
}
Gregorová, D., Hrouda, F. & Kohút, M. (2009), "Magnetic fabric of granitic composite pluton of the Velká Fatra Mountains (Western Carpathians, Slovakia): A Variscan remnant within the Alpine edifice?"; Geodinamica Acta, Vol. 22 (1-3) , pp. 57-72, Taylor & Francis Group
Abstract: The AMS study has been performed on various types of the basement - Variscan granitic and surrounding - Mesozoic sedimentary rocks in the Vel'ká Fatra Mountains, Tatric Superunit of the Central Western Carpathians. The Vel'ká Fatra Mts. provides good opportunity for AMS study because of composite S-type and I-type granite character of pluton and clear relations to Mesozoic sedimentary rocks in the cover and nappe positions. The granitic massif consists of the three types of weakly magnetic peraluminous granites (350-340 Ma in age), ranging from two-mica granites to biotite granodiorites in composition and carrying accessory monazite and ilmenite; whereby they resemble common S-type and/or Ilmenite Series granite. This pre-existing granitic body was intruded by relatively young (304 Ma old) metaluminous to subaluminous, strongly magnetic (due to magnetite) tonalitic intrusion of the I-type and/or Magnetite Series granite. In all S-types investigated as well as in the I-type tonalité body, the magnetic fabrics are not uniform, but slightly variable within a body and differing from body to body. The magnetic fabrics in all granitic rocks can be classified as mostly magmatic in origin, only subordinately affected by ductile deformation. The Alpine overprint of the magnetic fabric of the Variscan granite frequent in the central areas of the Central Western Carpathians was only weak in the Vel'ká Fatra Mts. and the magnetic fabrics of these granites thus mostly comprise the original Variscan magmatic fabrics. On the other hand, in the marginal parts of the Vel'ká Fatra Mts. the magnetic fabrics in granites are locally conformable to the deformational magnetic fabrics in surrounding sedimentary rocks (Mesozoic in age) thus indicating at least local effects of the Alpine deformation. The magnetic fabrics in Mesozoic sedimentary rocks covering the crystalline basement are partially (Cover Formation) to entirely (Nappe Units) deformational in origin. textcopyright 2009 Lavoisier SAS. All rights reserved.
BibTeX:
@article{Gregorova2009,
  author = {Gregorová, Dagmar and Hrouda, František and Kohút, Milan},
  title = {Magnetic fabric of granitic composite pluton of the Velká Fatra Mountains (Western Carpathians, Slovakia): A Variscan remnant within the Alpine edifice?},
  journal = {Geodinamica Acta},
  publisher = {Taylor & Francis Group},
  year = {2009},
  volume = {22},
  number = {1-3},
  pages = {57--72},
  url = {http://www.tandfonline.com/doi/abs/10.3166/ga.22.57-72?journalCode=tgda20#.VrDCgj-4rEY.mendeley},
  doi = {http://dx.doi.org/10.3166/ga.22.57-72}
}
Gregorová, D., Hrouda, F. & Kohút, M. (2009), "Magnetic fabric of granitic composite pluton of the Velká Fatra Mountains (Western Carpathians, Slovakia): A Variscan remnant within the Alpine edifice?"; Geodinamica Acta, Vol. 22 (1-3) , pp. 57-72, Taylor & Francis Group
Abstract: The AMS study has been performed on various types of the basement – Variscan granitic and surrounding – Mesozoic sedimentary rocks in the Velká Fatra Mountains, Tatric Superunit of the Central Western Carpathians. The Velká Fatra Mts. provides good opportunity for AMS study because of composite S-type and I-type granite character of pluton and clear relations to Mesozoic sedimentary rocks in the cover and nappe positions. The granitic massif consists of the three types of weakly magnetic peraluminous granites (350 – 340 Ma in age), ranging from two-mica granites to biotite granodiorites in composition and carrying accessory monazite and ilmenite; whereby they resemble common S-type and/or Ilmenite Series granite. This pre-existing granitic body was intruded by relatively young (304 Ma old) metaluminous to subaluminous, strongly magnetic (due to magnetite) tonalitic intrusion of the I-type and/or Magnetite Series granite. In all S-types investigated as well as in the I-type tonalite body, the magnetic fabr...
BibTeX:
@article{Gregorova2009,
  author = {Gregorová, Dagmar and Hrouda, František and Kohút, Milan},
  title = {Magnetic fabric of granitic composite pluton of the Velká Fatra Mountains (Western Carpathians, Slovakia): A Variscan remnant within the Alpine edifice?},
  journal = {Geodinamica Acta},
  publisher = {Taylor & Francis Group},
  year = {2009},
  volume = {22},
  number = {1-3},
  pages = {57--72},
  url = {http://www.tandfonline.com/doi/abs/10.3166/ga.22.57-72?journalCode=tgda20#.VrDCgj-4rEY.mendeley},
  doi = {http://dx.doi.org/10.3166/ga.22.57-72}
}
Gregorová, D., Hrouda, F. & Kohút, M. (2009), "Magnetic fabric of granitic composite pluton of the Velká fatra mountains (Western Carpathians, Slovakia): A Variscan remnant within the Alpine edifice?"; Geodinamica Acta, Vol. 22 (1-3) , pp. 57-72
Abstract: The AMS study has been performed on various types of the basement - Variscan granitic and surrounding - Mesozoic sedimentary rocks in the Vel'ká Fatra Mountains, Tatric Superunit of the Central Western Carpathians. The Vel'ká Fatra Mts. provides good opportunity for AMS study because of composite S-type and I-type granite character of pluton and clear relations to Mesozoic sedimentary rocks in the cover and nappe positions. The granitic massif consists of the three types of weakly magnetic peraluminous granites (350-340 Ma in age), ranging from two-mica granites to biotite granodiorites in composition and carrying accessory monazite and ilmenite; whereby they resemble common S-type and/or Ilmenite Series granite. This pre-existing granitic body was intruded by relatively young (304 Ma old) metaluminous to subaluminous, strongly magnetic (due to magnetite) tonalitic intrusion of the I-type and/or Magnetite Series granite. In all S-types investigated as well as in the I-type tonalité body, the magnetic fabrics are not uniform, but slightly variable within a body and differing from body to body. The magnetic fabrics in all granitic rocks can be classified as mostly magmatic in origin, only subordinately affected by ductile deformation. The Alpine overprint of the magnetic fabric of the Variscan granite frequent in the central areas of the Central Western Carpathians was only weak in the Vel'ká Fatra Mts. and the magnetic fabrics of these granites thus mostly comprise the original Variscan magmatic fabrics. On the other hand, in the marginal parts of the Vel'ká Fatra Mts. the magnetic fabrics in granites are locally conformable to the deformational magnetic fabrics in surrounding sedimentary rocks (Mesozoic in age) thus indicating at least local effects of the Alpine deformation. The magnetic fabrics in Mesozoic sedimentary rocks covering the crystalline basement are partially (Cover Formation) to entirely (Nappe Units) deformational in origin. textcopyright 2009 Lavoisier SAS. All rights reserved.
BibTeX:
@article{Gregorova2009a,
  author = {Gregorová, Dagmar and Hrouda, František and Kohút, Milan},
  title = {Magnetic fabric of granitic composite pluton of the Velká fatra mountains (Western Carpathians, Slovakia): A Variscan remnant within the Alpine edifice?},
  journal = {Geodinamica Acta},
  year = {2009},
  volume = {22},
  number = {1-3},
  pages = {57--72},
  doi = {http://dx.doi.org/10.3166/ga.22.57-72}
}
Hrouda, F., Faryad, S. W., Jeřábek, P. et al. (2009), "Primary magnetic fabric in an ultramafic body (Moldanubian Zone, European Variscides) survives exhumation-related granulite-amphibolite facies metamorphism"; Lithos, Vol. 111 (1-2) , pp. 95-111
Abstract: Serpentinized peridotite–clinopyroxenite, approximately 11×5 m in size, enclosed in high-pressure felsic granulite, occurs in a quarry near the village of Bory (Gföhl Unit of the Moldanubian Zone of Western Moravia, Czech Republic). The anisotropy of magnetic susceptibility (AMS) was used to investigate the fabrics of both the ultramafic body and the host granulite. The granulite shows a PT path from above 2 GPa/850–900 °C following nearly isothermal decompression to sillimanite stability field with subsequent cooling. Two foliations (S1-preserved only in isoclinal folds and the dominant S2 foliation parallel to leucocratic bands) are visible in granulite. Through investigating low-field variation of the AMS, one could resolve the AMS into the field-independent and field-dependent components. In the ultramafic body, the former component is due to mafic silicates and pure magnetite, while in the host granulite it is due to mafic silicates. The latter component is due to pyrrhotite in both the ultramafic body and granulite. The field-independent and field-dependent components are coaxial within ultramafic body and within granulite, but show different orientations between the ultramafic body and granulite. Consequently, the magnetic fabric in the ultramafic body is different from that in the host granulite even though they experienced common structural history during granulite facies metamorphism. The componental movements forming the granulite fabric were evidently not strong enough to strongly overprint the magnetic fabric of ultramafic rocks. The ultramafic rocks have therefore sufficient mechanical strength to maintain their pre-granulite facies metamorphic fabric even at such high temperatures and high pressure that are characteristic of granulite facies metamorphism.
BibTeX:
@article{Hrouda2009,
  author = {Hrouda, František and Faryad, Shah Wali and Jeřábek, Petr and Chlupáčová, Marta and Vitouš, Petr},
  title = {Primary magnetic fabric in an ultramafic body (Moldanubian Zone, European Variscides) survives exhumation-related granulite-amphibolite facies metamorphism},
  journal = {Lithos},
  year = {2009},
  volume = {111},
  number = {1-2},
  pages = {95--111},
  url = {http://www.sciencedirect.com/science/article/pii/S0024493708002284},
  doi = {http://dx.doi.org/10.1016/j.lithos.2008.10.004}
}
Hrouda, F., Krejčí, O., Potfaj, M. et al. (2009), "Magnetic fabric and weak deformation in sandstones of accretionary prisms of the Flysch and Klippen Belts of the Western Carpathians: Mostly offscraping indicated"; Tectonophysics, Vol. 479 (3-4) , pp. 254-270
Abstract: The magnetic fabric of sandstones in thrust sheets of the Flysch Belt of the Western Carpathians is basically sedimentary in origin, in minority of specimens slightly affected by deformation which is generally very weak, corresponding to the earliest deformation stage and to Types I-II in terms of the magnetic fabric classification of the accretionary prisms by Parés et al. (1999) and Aubourg et al. (2004), respectively. This indicates an absence of the return flow during the subduction process. The deformation is weaker in the thrust sheets located at the margins of the Flysch Belt (the Ždánice and Silesian thrust sheets in the west and the Bílé Karpaty and Oravská Magura thrust sheets in the east) than in the Fore-Magura, Rača and Bystrica thrust sheets located in the centre of the Flysch Belt. In the Ždánice and Silesian thrust sheets, the weak deformation reflects their sedimentation on the northern (“European”) slope of the Flysch Belt Basin and relatively short transport during their thrusting over the Foredeep. In the Bílé Karpaty and Oravská Magura thrust sheets that are located near the subduction zone, the weak deformation is explained by assuming early offscraping and frontal accreting of these thrust sheets. In the Pieniny Klippen Belt, the deformation of the Palaeogene sandstones (“peri-Klippen” Palaeogene) is stronger than that in the marginal thrust sheets (Ždánice, Silesian, Bílé Karpaty and Oravská Magura thrust sheets) of the Flysch Belt, but weaker than that in the central thrust sheets (Fore-Magura, Rača and Bystrica thrust sheets) of the Flysch Belt. This is in an apparent contradiction with strong macroscopic deformation of Mesozoic rocks of the Pieniny Klippen Belt, but understandable realizing that the sediments of the “peri-Klippen Palaeogene” were deformed only during the neoalpine orogenies in Palaeogene and Neogene after the main deformation (Late Cretaceous) in the Pieniny Klippen Belt.
BibTeX:
@article{Hrouda2009a,
  author = {Hrouda, František and Krejčí, Oldřich and Potfaj, Michal and Stráník, Zdeněk},
  title = {Magnetic fabric and weak deformation in sandstones of accretionary prisms of the Flysch and Klippen Belts of the Western Carpathians: Mostly offscraping indicated},
  journal = {Tectonophysics},
  year = {2009},
  volume = {479},
  number = {3-4},
  pages = {254--270},
  url = {http://www.sciencedirect.com/science/article/pii/S0040195109004338},
  doi = {http://dx.doi.org/10.1016/j.tecto.2009.08.016}
}
Hrouda, F., Faryad, S. W., Chlupáčová, M. et al. (2009), "Determination of field-independent and field-dependent components of anisotropy of susceptibility through standard AMS measurement in variable low fields II: An example from the ultramafic body and host granulitic rocks at Bory in the Moldanubian Zone of"; Tectonophysics, Vol. 466 (1-2) , pp. 123-134
Abstract: A large ultramafic body (garnet clinopyroxenite and garnet peridotite) embedded in felsic granulite at Bory (Moldanubian Zone of Western Moravia, Czech Republic) contains multiple carrier of susceptibility. Low-field variation of anisotropy of magnetic susceptibility (AMS) enables the separation of the field independent and low-field dependent AMS components to be made. In granulite, the former is carried by paramagnetic minerals and a subordinate admixture of magnetite, while the latter is due to pyrrhotite. In the ultramafite, the field-independent component is carried by pure magnetite formed by serpentinization, while the field-dependent component is due to pyrrhotite and subordinate paramagnetic minerals. Despite small differences, all AMS components are roughly coaxial both within granulite and within ultramafite, but very different between granulite and ultramafite. The difference indicates that the forces that imposed the later granulite fabric were not strong enough to obliterate the original magnetic fabric of the ultramafites.
BibTeX:
@article{Hrouda2009b,
  author = {Hrouda, František and Faryad, Shah Wali and Chlupáčová, Marta and Jeřábek, Petr and Kratinová, Zuzana},
  title = {Determination of field-independent and field-dependent components of anisotropy of susceptibility through standard AMS measurement in variable low fields II: An example from the ultramafic body and host granulitic rocks at Bory in the Moldanubian Zone of},
  journal = {Tectonophysics},
  year = {2009},
  volume = {466},
  number = {1-2},
  pages = {123--134},
  url = {http://linkinghub.elsevier.com/retrieve/pii/S0040195108005015},
  doi = {http://dx.doi.org/10.1016/j.tecto.2008.10.014}
}
Hrouda, F. (2009), "Determination of field-independent and field-dependent components of anisotropy of susceptibility through standard AMS measurement in variable low fields I: Theory"; Tectonophysics, Vol. 466 (1-2) , pp. 114-122
Abstract: Three methods were developed for simultaneous determination of the field-independent susceptibility tensor and the initial susceptibility tensor of MD ferromagnetic fraction, all based on standard measurement of the AMS in variable fields within the Rayleigh Law range. The former tensor reflects possible effects of diamagnetic and paramagnetic minerals, pure magnetite, SD ferromagnetic minerals, and initial susceptibility of MD ferromagnetic minerals. The initial susceptibility tensor of MD ferromagnetic fraction does not however reflect the effect of the entire fraction, because the effect of the SD sub-fraction contributes to the field-independent susceptibility tensor. The differences in the degree of AMS of the field-independent susceptibility tensor and that of the initial susceptibility tensor of MD ferromagnetic fraction may be useful in magnetic granulometry.
BibTeX:
@article{Hrouda2009c,
  author = {Hrouda, František},
  title = {Determination of field-independent and field-dependent components of anisotropy of susceptibility through standard AMS measurement in variable low fields I: Theory},
  journal = {Tectonophysics},
  year = {2009},
  volume = {466},
  number = {1-2},
  pages = {114--122},
  url = {http://linkinghub.elsevier.com/retrieve/pii/S0040195108002564},
  doi = {http://dx.doi.org/10.1016/j.tecto.2008.05.026}
}
Závada, P., Schulmann, K., Lexa, O. et al. (2009), "The mechanism of flow and fabric development in mechanically anisotropic trachyte lava"; Journal of Structural Geology, Vol. 31 (11) , pp. 1295-1307
Abstract: Anisotropy of magnetic susceptibility (AMS) and Electron back-scattered diffraction (EBSD) of magnetite and sanidine fabrics throughout an eroded trachyte lava dome in Tertiary volcanic province of the NW Czech Republic revealed two fabric types. The high degree of AMS fabric is associated with sanidine textural domains similar to normal kink bands (Type I fabric) and occupies the whole body except the SW margin. Folded fabric and low anisotropy of AMS also in the SW margin reveals sanidine alignment domains resembling reverse kink-bands (Type II fabric). The flow of trachyte lava occurred via simultaneous slip of sanidine crystals along their (010) planes and also by readjustment of the textural domain boundaries according to the fibre-slip theory. This microfabric study suggests that the Type II fabrics resulted from collapse of vertically anisotropic trachyte crystal mush above the feeding conduit. Type I fabric is interpreted to originate from Type II fabrics by further stretching of highly attenuated fold limbs. Asymmetric Type I fabrics along margins of the dome are related to outflow of trachyte lava away from the conduit region due to divergent flow. The trachyte fabric zonality is interpreted to reflect the process of successive emplacement of progressively rotated trachyte lava lobes within a lava dome that locally preserves the collapsed and folded vertical fabrics.
BibTeX:
@article{Zavada2009,
  author = {Závada, Prokop and Schulmann, Karel and Lexa, Ondrej and Hrouda, František and Haloda, Jakub and Týcová, Patricie},
  title = {The mechanism of flow and fabric development in mechanically anisotropic trachyte lava},
  journal = {Journal of Structural Geology},
  year = {2009},
  volume = {31},
  number = {11},
  pages = {1295--1307},
  url = {http://www.sciencedirect.com/science/article/pii/S0191814109000790},
  doi = {http://dx.doi.org/10.1016/j.jsg.2009.04.002}
}
Hasalová, P., Schulmann, K., Lexa, O. et al. (2008), "Origin of migmatites by deformation-enhanced melt infiltration of orthogneiss: a new model based on quantitative microstructural analysis"; Journal of Metamorphic Geology, Vol. 26 (1) , pp. 29-53, Blackwell Publishing Ltd
Abstract: A detailed field study reveals a gradual transition from high-grade solid-state banded orthogneiss via stromatic migmatite and schlieren migmatite to irregular, foliation-parallel bodies of nebulitic migmatite within the eastern part of the Gföhl Unit (Moldanubian domain, Bohemian Massif). The orthogneiss to nebulitic migmatite sequence is characterized by progressive destruction of well-equilibrated banded microstructure by crystallization of new interstitial phases (Kfs, Pl and Qtz) along feldspar boundaries and by resorption of relict feldspar and biotite. The grain size of all felsic phases decreases continuously, whereas the population density of new phases increases. The new phases preferentially nucleate along high-energy like–like boundaries causing the development of a regular distribution of individual phases. This evolutionary trend is accompanied by a decrease in grain shape preferred orientation of all felsic phases. To explain these data, a new petrogenetic model is proposed for the origin of felsic migmatites by melt infiltration from an external source into banded orthogneiss during deformation. In this model, infiltrating melt passes pervasively along grain boundaries through the whole-rock volume and changes completely its macro- and microscopic appearance. It is suggested that the individual migmatite types represent different degrees of equilibration between the host rock and migrating melt during exhumation. The melt topology mimicked by feldspar in banded orthogneiss forms elongate pockets oriented at a high angle to the compositional banding, indicating that the melt distribution was controlled by the deformation of the solid framework. The microstructure exhibits features compatible with a combination of dislocation creep and grain boundary sliding deformation mechanisms. The migmatite microstructures developed by granular flow accompanied by melt-enhanced diffusion and/or melt flow. However, an AMS study and quartz microfabrics suggest that the amount of melt present did not exceed a critical threshold during the deformation to allow free movements of grains.
BibTeX:
@article{JMG:JMG743,
  author = {Hasalová, Pavlína and Schulmann, Karel and Lexa, Ondrej and Štípská, Pavla and Hrouda, František and Ulrich, S and Haloda, Jakub and Týcová, Patricie},
  title = {Origin of migmatites by deformation-enhanced melt infiltration of orthogneiss: a new model based on quantitative microstructural analysis},
  journal = {Journal of Metamorphic Geology},
  publisher = {Blackwell Publishing Ltd},
  year = {2008},
  volume = {26},
  number = {1},
  pages = {29--53},
  url = {http://dx.doi.org/10.1111/j.1525-1314.2007.00743.x},
  doi = {http://dx.doi.org/10.1111/j.1525-1314.2007.00743.x}
}
Kadlec, J., Chadima, M., Lisá, L. et al. (2008), "Clastic cave deposits in Botovskaya cave (Eastern Siberia, Russian Federation)"; Journal of Cave and Karts Studies, Vol. 70 (3) , pp. 142-155
Abstract: Botovskaya Cave is a typical example of a two-dimensional maze with a total length of explored passages exceeding 60 km, which represents the longest limestone cave system in the Russian Federation. The clastic cave sediments filling the cave passages differ in both mineral and mineral magnetic properties and were deposited under different hydrological conditions. The older portion of the clastic cave fills was derived from overlying sandstones, whereas the properties of younger cave sediments show closer affinity to the soils and weathering products originating on the plateau above the cave. The cave sediments underwent repeated periods of deposition and erosion during the Tertiary (?) and Pleistocene. The last catastrophic erosion event occurred in the cave more than 350 ka based on flowstone dating. Water seeping through the overlying sandstone body causes collapses of sandstone slabs from the cave passage ceilings, forming the youngest portion of the clastic cave fills.
BibTeX:
@article{KadlecJ.ChadimaM.LisaL.HercmanH.OsintsevA.2008,
  author = {Kadlec, Jaroslav and Chadima, Martin and Lisá, Lenka and Hercman, Helena and Osintsev, Alexandr and Oberhänsli, Hedi},
  title = {Clastic cave deposits in Botovskaya cave (Eastern Siberia, Russian Federation)},
  journal = {Journal of Cave and Karts Studies},
  year = {2008},
  volume = {70},
  number = {3},
  pages = {142--155},
  url = {https://caves.org/pub/journal/PDF/v70/cave-70-03-142.pdf}
}
Aïfa, T. (2007), "Structural evolution of the Prague synform ( Czech Republic ) during Silurian times : An AMS , rock magnetism , and paleomagnetic study of the Svatý Jan pod Skalou dikes . Consequences for the nappes emplacement"; Geological Society of America Special Papers, Vol. 2423 (11) , pp. 249-265
Abstract: Silurian effusive basalts and volcaniclastics compose the Svatý Jan volcanic center, which is located in the northwestern limb of the Prague synform, where three major volcanic phases have been recognized: the first one of early to mid-Wenlock and the last of mid-Ludlow age. Two alkaline basalt dikes of late Wenlock to mid-Ludlow age, respectively tilted to the west and to the northeast, as observed in a 100-m-thick tuff sequence, which represents the second volcanic phase, have been extensively sampled. An anisotropy of the magnetic susceptibility (AMS) study of seventy-nine specimens taken from a 5-m-thick dike (dike1) and thirty-two specimens cored in a 3.5-m-thick dike (dike2) shows two different fabrics, carried mainly by Ti-magnetite and/or magnetite, which are considered to be related to the transtensional opening phase of the dikes. Four components of magnetization, attributed to Middle-Late Silurian (C1), Middle-Late Carboniferous (C2), Cretaceous (B), and Paleocene (D), in agreement with already-published directions for the Bohemian Massif, have been isolated. They are carried by Ti-magnetite for components C1 and C2, hematite and goethite for components B and D. The opening mode, which controlled both dikes, corresponds to a dextral transtensional regime, as deduced from the AMS K1 axis. They may have been opened during several magmatic stages related to different injections during late Wenlock to mid-Ludlow times. The first stage is dominant and controlled by the primary fabric, which is mainly oblate. With a NNW-SSE strike, perpendicular to the shortening direction, this fabric is in agreement with the direction of emplacement of the nappes during the Late Devonian. At that time the nappes emplacement that pre-dates this direction was probably associated with the sinistral closure of the Rheic Ocean, in agreement with post-Givetian folding and faulting, which deformed the synform infill and closed the Barrandian marine sedimentary cycle.
BibTeX:
@article{Aïfa01012007,
  author = {Aïfa, Tahar},
  title = {Structural evolution of the Prague synform ( Czech Republic ) during Silurian times : An AMS , rock magnetism , and paleomagnetic study of the Svatý Jan pod Skalou dikes . Consequences for the nappes emplacement},
  journal = {Geological Society of America Special Papers},
  year = {2007},
  volume = {2423},
  number = {11},
  pages = {249--265},
  url = {http://specialpapers.gsapubs.org/content/423/249.abstract},
  doi = {http://dx.doi.org/10.1130/2007.2423(11}
}
Hrouda, F. (2007), "Magnetic susceptibility, anisotropy."; , Encyclopedia of Geomagnetism and Paleomagnetism , pp. 546-560
BibTeX:
@incollection{Hrouda2007,
  author = {Hrouda, František},
  title = {Magnetic susceptibility, anisotropy.},
  booktitle = {Encyclopedia of Geomagnetism and Paleomagnetism},
  year = {2007},
  pages = {546--560}
}
Jezek, J. & Hrouda, F. (2007), "A program for magnetic susceptibility-equivalent pore conversion"; Geochemistry, Geophysics, Geosystems, Vol. 8 (10) , pp. n/a-n/a
Abstract: Pore magnetic anisotropy can be used to estimate the average geometry of void spaces in rocks in the form of the equivalent pore (EP) ellipsoid. Direct computation of EP from measured magnetic susceptibility is impossible. We present a method and a Matlab program for automatic magnetic susceptibility–equivalent pore conversion. Input data are the magnetic parameters (P and T, or L and F) representing the bulk magnetic anisotropy, and the intrinsic susceptibility of the fluid used in the measurement. EP is estimated iteratively by a repeated look-up table procedure using P and T values computed in a coarse grid of EP axial ratios. The program may be downloaded from the EarthRef.org Digital Archive.
BibTeX:
@article{Jezek2007,
  author = {Jezek, J. and Hrouda, František},
  title = {A program for magnetic susceptibility-equivalent pore conversion},
  journal = {Geochemistry, Geophysics, Geosystems},
  year = {2007},
  volume = {8},
  number = {10},
  pages = {n/a--n/a},
  url = {http://doi.wiley.com/10.1029/2007GC001709},
  doi = {http://dx.doi.org/10.1029/2007GC001709}
}
Ježek, J. & Hrouda, F. (2007), "SUSIE: A program for inverse strain estimation from magnetic susceptibility"; Computers & Geosciences, Vol. 33 (6) , pp. 749-759
Abstract: SUsceptibility–Strain Inverse Estimation (SUSIE) is a Matlab program for the inversion of magnetic susceptibility to irrotational strain. Input data are the bulk susceptibility principal values or their equivalent (magnetic parameters P and T), parameters of magnetic grains (shape, magnetic susceptibility, initial orientation, and rotational response to deformation). SUSIE estimates strain corresponding to input AMS data iteratively, by a repeated look-up table procedure that uses the map of P and T values computed in a coarse strain grid. Usually not more than two or three iterations are needed to obtain the strain estimate that satisfy up to two decimal places of the input P and T values. An example of the use of the program is given.
BibTeX:
@article{Jezek2007a,
  author = {Ježek, Josef and Hrouda, František},
  title = {SUSIE: A program for inverse strain estimation from magnetic susceptibility},
  journal = {Computers & Geosciences},
  year = {2007},
  volume = {33},
  number = {6},
  pages = {749--759},
  url = {http://www.sciencedirect.com/science/article/pii/S0098300407000222},
  doi = {http://dx.doi.org/10.1016/j.cageo.2006.11.002}
}
Hrouda, F. (2007), "Anisotropy of magnetic susceptibility of rocks in the Rayleigh Law region: Modelling errors arising from linear fit to non-linear data"; Studia Geophysica et Geodaetica, Vol. 51 (3) , pp. 423-438
Abstract: The anisotropy of magnetic susceptibility (AMS) within the Rayleigh Law range was investigated theoretically, using mathematical modelling. It was revealed that the orientations of the principal susceptibilities and the shape parameter vary with field so weakly that these variations can be regarded as negligible from the practical point of view. The degree of AMS increases with field according to the degree of anisotropy of the initial susceptibility used and according to the intensity of susceptibility change with field of the mineral considered. The degree of AMS calculated using linear theory is very near to the degree of AMS following from the analysis of AMS within the Rayleigh Law range. If it is desirable to correct the field-dependent degree of AMS, a simple technique is suggested based on measurement of the AMS in two fields.
BibTeX:
@article{ref1,
  author = {Hrouda, František},
  title = {Anisotropy of magnetic susceptibility of rocks in the Rayleigh Law region: Modelling errors arising from linear fit to non-linear data},
  journal = {Studia Geophysica et Geodaetica},
  year = {2007},
  volume = {51},
  number = {3},
  pages = {423--438},
  url = {http://link.springer.com/10.1007/s11200-007-0024-5},
  doi = {http://dx.doi.org/10.1007/s11200-007-0024-5}
}
Houša, V., Pruner, P., Zakharov, V. et al. (2007), "Boreal-tethyan correlation of the Jurassic-Cretaceous boundary interval by magneto- and biostratigraphy"; Stratigraphy and Geological Correlation, Vol. 15 (3) , pp. 297-309, MAIK Nauka/Interperiodica distributed exclusively by Springer Science+Business Media LLC.
Abstract: As a result of detail sampling and paleomagnetic study of the 27-m-thick section of Jurassic–Cre- taceous boundary beds in the Nordvik Peninsula (Anabar Bay, Laptev Sea), a succession of M-zones correlative with chrons M20n–M17r is established for the first time in the Boreal deposits. Inside the normal polarity zone corresponding to Chron M20n, a thin interval of reversed polarity, presumably an equivalent of the Kysuca Sub- zone (M20n.1r), is discovered. The other thin interval of reversed polarity established within the next normal polarity zone (M19n) is correlated with the Brodno Subzone (M19n.1r). The same succession of normal and reversed polarity zones has been discovered recently in the Jurassic–Cretaceous boundary beds of the Tethyan sections: in the Bosso Valley (Italy), at the Brodno (Slovak Republic) and Puerto Esca o (Spain) sites. Corre- n ˜ lation of successions established lead us to conclusion, that the Jurassic–Cretaceous boundary corresponds in the Panboreal Superrealm to a level within the Craspedites taimyrensis Zone of the upper Volgian Substage. Hence, the greatest part of Volgian Stage should be included into the Jurassic System. Biostratigraphic data do not contradict this conclusion.
BibTeX:
@article{springerlink:10.1134/S0869593807030057,
  author = {Houša, V and Pruner, Petr and Zakharov, Victor and Kostak, M and Chadima, Martin and Rogov, Mikhail and Šlechta, Stanislav and Mazuch, Martin},
  title = {Boreal-tethyan correlation of the Jurassic-Cretaceous boundary interval by magneto- and biostratigraphy},
  journal = {Stratigraphy and Geological Correlation},
  publisher = {MAIK Nauka/Interperiodica distributed exclusively by Springer Science+Business Media LLC.},
  year = {2007},
  volume = {15},
  number = {3},
  pages = {297--309},
  url = {http://link.springer.com/10.1134/S0869593807030057},
  doi = {http://dx.doi.org/10.1134/S0869593807030057}
}
Stráník, Z., Hrouda, F., Otava, J. et al. (2007), "The Upper Oligocene-Lower Miocene Krosno lithofacies in the Carpathian Flysch Belt (Czech Republic): Sedimentology, provenance and magnetic fabrics"; Geologica Carpathica, Vol. 58 (4) , pp. 321-332
Abstract: The Krosno lithofacies is the Upper Oligocene-Lower Miocene synorogenic sequence that terminates the flysch sedimentation in the orogenic system of the Western Carpathians. Its deposition replaced the hypoxic sedimentation of the underlying Oligocene Menilite Formation. This change in deposition was connected with the Helvetian Neoalpine orogeny which iniciated the fundamental rearangement in the orogenic belt, gradual isolation of foreland basins and creation of the "Protoparatethys". The differences in deformation between the Krosno lithofacies and the underlying Upper Cretaceous to Eocene strata are recorded in all tectonofacial units of the Outer (Menilite-Krosno) Group of thrust sheets. Moreover, a trend towards increase of ductile deformation from the outer to the inner margin of the Flysch Belt is evident. The investigation of translucent heavy minerals produced evidence of different spectra between the Krosno lithofacies and underlying strata of individual tectonofacial units. The spatial distribution of the Krosno lithofacies and the transport of clastic material from the SE indicate the deposition of a submarine fan that prograded to the NW.
BibTeX:
@article{Stranik2007,
  author = {Stráník, Zdeněk and Hrouda, František and Otava, Jiří and Gilíková, Helena and Švábenická, Lilian},
  title = {The Upper Oligocene-Lower Miocene Krosno lithofacies in the Carpathian Flysch Belt (Czech Republic): Sedimentology, provenance and magnetic fabrics},
  journal = {Geologica Carpathica},
  year = {2007},
  volume = {58},
  number = {4},
  pages = {321--332},
  url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-34547106473&partnerID=tZOtx3y1}
}
Chadima, M., Hrouda, F. & Melichar, R. (2006), "Magnetic fabric study of the SE Rhenohercynian Zone (Bohemian Massif): Implications for dynamics of the Paleozoic accretionary wedge"; Tectonophysics, Vol. 418 (1-2) , pp. 93-109
Abstract: The progressive deformation recorded in the magnetic fabric of sedimentary rocks was studied in the SE Rhenohercynian Zone (RHZ), eastern margin of the Bohemian Massif, Czech Republic. Almost 800 oriented samples of the Lower Carboniferous mudstones and graywackes were collected from the SSE part of the Czech RHZ, so-called the Drahany Upland. The anisotropy of magnetic susceptibility (AMS) is predominantly controlled by the preferred orientation of paramagnetic phyllosilicates, mainly iron-bearing chlorites. A regional distribution of the magnetic fabric within the Drahany Upland revealed an increasing deformation from the SSE to the NNW. In the SE, the magnetic fabric is bedding-parallel with magnetic lineation scattered in the bedding plane or trending N–S to NNE–SSW. Further to the NW, the magnetic foliation rotates from the bedding-parallel orientation to the orientation parallel to the evolving cleavage. This rotation is accompanied by a decrease of the anisotropy degree and the prolate nature of the anisotropy ellipsoids. The magnetic lineation is parallel to the strike of the bedding, bedding/cleavage intersection, pencil structure or the fold axes on a regional scale. In the NW part of the Drahany Upland, the magnetic foliation becomes parallel to the cleavage accompanied by an increase of the anisotropy degree and the oblate nature of the anisotropy ellipsoids. The increasing trend of deformation corresponds to the SSE–NNW increase in the degree of anchimetamorphism; both trends being oblique to the main lithostratigraphic formations as typically observed in the sedimentary rocks of the accretionary wedges. The SSE–NNW increase in deformation and anchimetamorphism continues to the Nízký Jeseník Mts., representing the northern part of the same accretionary wedge. The kinematics of deformation could not be unambiguously assessed. The observed magnetic fabric may reflect either lateral shortening or horizontal simple shear or a combination of both mechanisms. Regarding the subduction process, it seems that the sedimentary sequences of the Drahany Upland were subducted, partly offscraped and accreted frontally or partly underplated as opposed to the Nízký Jeseník Mts. where some return flow must have occurred.
BibTeX:
@article{Chadima2006,
  author = {Chadima, Martin and Hrouda, František and Melichar, Rostislav},
  title = {Magnetic fabric study of the SE Rhenohercynian Zone (Bohemian Massif): Implications for dynamics of the Paleozoic accretionary wedge},
  journal = {Tectonophysics},
  year = {2006},
  volume = {418},
  number = {1-2},
  pages = {93--109},
  url = {http://www.sciencedirect.com/science/article/pii/S0040195106000515},
  doi = {http://dx.doi.org/10.1016/j.tecto.2005.12.015}
}
Chadima, M., Pruner, P., Šlechta, S. et al. (2006), "Magnetic fabric variations in Mesozoic black shales, Northern Siberia, Russia: Possible paleomagnetic implications"; Tectonophysics, Vol. 418 (1-2) , pp. 145-162
Abstract: A 28-m-long section situated on the coast of the Arctic Ocean, Russia (74°N, 113°E) was extensively sampled primarily for the purpose of magnetostratigraphic investigations across the Jurassic/Cretaceous boundary. The section consists predominantly of marine black shales with abundant siderite concretions and several distinct siderite cemented layers. Low-field magnetic susceptibility (k) ranges from 8×10−5 to 2×10−3 SI and is predominantly controlled by the paramagnetic minerals, i.e. iron-bearing chlorites, micas, and siderite. The siderite-bearing samples possess the highest magnetic susceptibility, usually one order of magnitude higher than the neighboring rock. The intensity of the natural remanent magnetization (M0) varies between 1×10−5 and 6×10−3 A/m. Several samples possessing extremely high values of M0 were found. There is no apparent correlation between the high k and high M0 values; on the contrary, the samples with relatively high M0 values possess average magnetic susceptibility and vice versa. According to the low-field anisotropy of magnetic susceptibility (AMS), three different groups of samples can be distinguished. In the siderite-bearing samples (i), an inverse magnetic fabric is observed, i.e., the maximum and minimum principal susceptibility directions are interchanged and the magnetic fabric has a distinctly prolate shape. Triaxial-fabric samples (ii), showing an intermediate magnetic fabric, are always characterized by high M0 values. It seems probable that the magnetic fabric is controlled by the preferred orientation of paramagnetic phyllosilicates, e.g., chlorite and mica, and by some ferromagnetic mineral with anomalous orientation in relation to the bedding plane. Oblate-fabric samples (iii) are characterized by a bedding-controlled magnetic fabric, and by moderate magnetic susceptibility and M0 values. The magnetic fabric is controlled by the preferred orientation of phyllosilicate minerals and, to a minor extent, by a ferrimagnetic fraction, most probably detrital magnetite. Considering the magnetic fabric together with paleomagnetic component analyses, the siderite-bearing, and the high-NRM samples (about 15% of samples) were excluded from further magnetostratigraphic research.
BibTeX:
@article{Chadima2006a,
  author = {Chadima, Martin and Pruner, Petr and Šlechta, Stanislav and Grygar, Tomáš and Hirt, Ann M},
  title = {Magnetic fabric variations in Mesozoic black shales, Northern Siberia, Russia: Possible paleomagnetic implications},
  journal = {Tectonophysics},
  year = {2006},
  volume = {418},
  number = {1-2},
  pages = {145--162},
  url = {http://www.sciencedirect.com/science/article/pii/S0040195106000540},
  doi = {http://dx.doi.org/10.1016/j.tecto.2005.12.018}
}
Hrouda, F., Chlupáčová, M. & Mrázová, Š. (2006), "Low-field variation of magnetic susceptibility as a tool for magnetic mineralogy of rocks"; Physics of the Earth and Planetary Interiors, Vol. 154 (3-4) , pp. 323-336
Abstract: Low-field variation of magnetic susceptibility was investigated on a collection of several hundreds specimens of various minerals and rocks using the KLY-4S Kappabridge. The measurement is fully automated, being executed in 21 distinct fields ranging from 2 to 450A/m (in one frequency of 875Hz). The measurement is rapid, 7min per specimen, so that large collections of specimens can be investigated. The results can be processed both graphically and mathematically. For the latter processing, parameters of two kinds were introduced. One characterizes the susceptibility change with field, the other one characterizes the field in which the susceptibility no longer obeys the Rayleigh law and starts becoming more complex. The results were evaluated statistically. Remarkable differences were revealed between individual minerals and between some rock types. For example, the field variation of susceptibility of pyrrhotite is in general an order of magnitude larger than that of titanomagnetite. The susceptibility increase in pyrrhotite starts at the field an order of magnitude lower than that of titanomagnetite. Low-field variation of susceptibility then appears as an interesting phenomeon that helps in the identification of magnetic minerals and in some cases also in assessing the compositional variation of them.
BibTeX:
@article{Hrouda2006,
  author = {Hrouda, František and Chlupáčová, Marta and Mrázová, Štěpánka},
  title = {Low-field variation of magnetic susceptibility as a tool for magnetic mineralogy of rocks},
  journal = {Physics of the Earth and Planetary Interiors},
  year = {2006},
  volume = {154},
  number = {3-4},
  pages = {323--336},
  url = {http://www.sciencedirect.com/science/article/pii/S0031920105002657},
  doi = {http://dx.doi.org/10.1016/j.pepi.2005.09.013}
}
Petrovský, E. & Kapička, A. (2006), "On determination of the Curie point from thermomagnetic curves"; Journal of Geophysical Research: Solid Earth, Vol. 111 (B12) , pp. n/a--n/a
Abstract: In many rock magnetic studies, information on magnetic mineralogy is of crucial importance. Besides standard analytical methods, such as X-ray spectroscopy, more sensitive thermomagnetic analyses are often used. Temperature dependence of magnetic parameters can serve as basis for determination of magnetic second-order phase transition temperatures. Although limited by several drawbacks, the most serious being thermally induced transformations of the original minerals, this method provides useful information not only about the presence of magnetic minerals, but also additional knowledge on, e.g., the prevailing grain size distribution or degree of substitution. In thermomagnetic analysis, temperature dependence of two parameters, induced magnetization and magnetic susceptibility, is mostly used. However, let us say because of historical reasons, the same approach for the Curie point determination has been often used in analyzing the two parameters. In our contribution, we discuss the physical principles of the two parameters, showing that the methods developed and used for induced magnetization cannot be used also for temperature dependence of magnetic susceptibility because there is no physical justification to do so. Otherwise, the error in determining the Curie point can be some few degrees but can reach also several tens of degrees. Such an error has serious consequences for further interpretation of the data, e.g., in terms of degree of Ti substitution in Ti magnetite.
BibTeX:
@article{JGRB:JGRB14997,
  author = {Petrovský, E and Kapička, A},
  title = {On determination of the Curie point from thermomagnetic curves},
  journal = {Journal of Geophysical Research: Solid Earth},
  year = {2006},
  volume = {111},
  number = {B12},
  pages = {n/a----n/a},
  url = {http://dx.doi.org/10.1029/2006JB004507},
  doi = {http://dx.doi.org/10.1029/2006JB004507}
}
Jones, S., Benson, P. & Meredith, P. (2006), "Pore fabric anisotropy: Testing the equivalent pore concept using magnetic measurements on synthetic voids of known geometry"; Geophysical Journal International, Vol. 166 (1) , pp. 485-492
Abstract: We present an experimental and modelling study of pore fabric anisotropy using the method of anisotropy of magnetic susceptibility (AMS) applied to synthetic void spaces of known dimensions saturated with a high susceptibility magnetic ferrofluid. We analysed the data using the equivalent pore concept (EPC) proposed by Hrouda et al., who consider the theoretical demagnetization factors of an ellipsoid in order to relate physical pore fabric to magnetic measurements of lineation, foliation and bulk anisotropy. To test this theory, synthetic samples were prepared from cylindrical polycarbonate blanks, 25 mm in diameter by 22 mm long. A variety of 'special fabrics' were prepared by machining internal void spaces of: (a) a quasi-spherical fabric comprising a cylinder 10 mm in diameter by 8.8 mm long, (b) a capillary-like fabric comprising a set of 19 equally spaced holes, (c) a bedding-like fabric comprising a linear row of five larger diameter holes and (d) a crack-like fabric comprising a stack of four penny-shaped voids. A second set of quasi-spheroidal fabrics were prepared by machining a hemispherical cutter to different depths into the blanks. Eight samples were prepared with principal axial to radial axis ratios (a/r) from 0.75 to 1.3 (i.e. from oblateness through sphericity to prolateness). With the exception of the quasi-spherical fabric, the 'special fabrics' exhibit high anisotropy, with a maximum foliation of 1.41 and a maximum lineation of 1.29. Using a ferrofluid with a fixed intrinsic susceptibility of 1.09 SI, the quasi-spheroidal shape effect is investigated with change in value of the a/r ratio. As the a/r ratio increases, foliation decreases and lineation increases, reflecting the change from an oblate to a prolate fabric. The EPC is then used to estimate the physical void anisotropy from the magnetic measurements of lineation and foliation for direct comparison with the known geometry. Overall, the EPC method makes a reasonable job of estimating the void geometry, but it underestimates the physical void anisotropy by an average of about 8 per cent. We, therefore, report the effect of varying the intrinsic susceptibility of the ferrofluid on a void with a constant a/r ratio of 1.2. As ferrofluid concentration is increased, the EPC predicted void geometry converges to the known physical void geometry. However, even for the highest intrinsic susceptibility ferrofluid used (3.34 SI) the EPC underpredicts the known void anisotropy. We, therefore, propose a simple, empirical correction factor that allows the EPC method accurately to predict real physical void space anisotropy from AMS measurements.
BibTeX:
@article{Jones2006,
  author = {Jones, Sebastian and Benson, Philip and Meredith, Philip},
  title = {Pore fabric anisotropy: Testing the equivalent pore concept using magnetic measurements on synthetic voids of known geometry},
  journal = {Geophysical Journal International},
  year = {2006},
  volume = {166},
  number = {1},
  pages = {485--492},
  doi = {http://dx.doi.org/10.1111/j.1365-246X.2006.03021.x}
}
Kapička, A., Hrouda, F., Petrovský, E. et al. (2006), "Effect of plastic deformation in laboratory conditions on magnetic anisotropy of sedimentary rocks"; High Pressure Research, Vol. 26 (4) , pp. 549-553
Abstract: In order to correlate the degree of plastic deformation and low-field magnetic anisotropy, a series of laboratory pressure experiments were carried out on a batch of grey marls. Samples were gradually deformed using triaxial high-pressure device. The confining pressure of 300MPa was used, yielding maximum relative deformation up to 20% depending upon the uniaxial differential stress. In the range of initial deformation, irregular changes of the anisotropy parameters were typically observed. This effect is related to variable pre-deformation orientation of the anisotropy ellipsoid in the samples. At higher deformation, samples are characterized by increasing degree of magnetic anisotropy and by increasing foliation. Reorientation of paramagnetic phyllosilicate grains due to plastic deformation seems to be the most probable mechanism of the magnetic anisotropy changes. textcopyright 2006 Taylor & Francis.
BibTeX:
@article{Kapicka2006,
  author = {Kapička, Aleš and Hrouda, František and Petrovský, Eduard and Poláček, J},
  title = {Effect of plastic deformation in laboratory conditions on magnetic anisotropy of sedimentary rocks},
  journal = {High Pressure Research},
  year = {2006},
  volume = {26},
  number = {4},
  pages = {549--553},
  url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-69249149036&partnerID=tZOtx3y1},
  doi = {http://dx.doi.org/10.1080/08957950601092390}
}
Kratinová, Z., Závada, P., Hrouda, F. et al. (2006), "Non-scaled analogue modelling of AMS development during viscous flow: A simulation on diapir-like structures"; Tectonophysics, Vol. 418 (1-2) , pp. 51-61
Abstract: Development of magnetic fabric within a diapirically ascending columnar body was investigated using non-scaled analogue model made of plaster of Paris containing small amount of fine-grained homogeneously mixed magnetite. The apparatus for the modelling consists of a manual squeezer with calibrated spring and a Perspex container. Set of weak coloured layers at the bottom of the container was forced to intrude overlying fine-grained sand through a hole in a board attached to the squeezer. The development of AMS fabric is correlated with complex flow pattern indicated by coloured and originally horizontal plaster layers. Strongly constrictional and vertical fabric in the base and in the lower domain of the diapir resulting from convergent and upwards flows is overprinted by subhorizontal oblate fabrics due to vertical flattening and initial divergent flow in the apical parts. The measured AMS fabrics are compared with natural examples of magmatic stocks and dykes.
BibTeX:
@article{Kratinova2006,
  author = {Kratinová, Zuzana and Závada, Prokop and Hrouda, František and Schulmann, Karel},
  title = {Non-scaled analogue modelling of AMS development during viscous flow: A simulation on diapir-like structures},
  journal = {Tectonophysics},
  year = {2006},
  volume = {418},
  number = {1-2},
  pages = {51--61},
  url = {http://www.sciencedirect.com/science/article/pii/S0040195106000485},
  doi = {http://dx.doi.org/10.1016/j.tecto.2005.12.013}
}
Hrouda, F., Chlupáčová, M. & Pokorný, J. (2006), "Low-field variation of magnetic susceptibility measured by the KLY-4S Kappabridge and KLF-4A magnetic susceptibility meter: Accuracy and interpretational programme"; Studia Geophysica et Geodaetica, Vol. 50 (2) , pp. 283-299
Abstract: The KLY-4S Kappabridge and KLF-4A Magnetic Susceptibility Meter enable automated measurement of susceptibility variation with field in the ranges of 2--450 A/m and 5--300 A/m (in effective values), respectively. Unfortunately, the measurement accuracy decreases with decreasing field and it is not easy to decide whether the susceptibility variation at the lowest fields is natural phenomenon or results from measuring errors. To overcome this problem, the accuracies of both the above instruments were investigated experimentally using artificial specimens (mixture of pure magnetite and plaster of Paris) with variable susceptibilities ranging from 1 texttimes 10−5 to 5 texttimes 10−2. The complete curve of the field variation of susceptibility of each specimen was measured 10 times and the relative error was calculated for each field.
BibTeX:
@article{ref1,
  author = {Hrouda, František and Chlupáčová, Marta and Pokorný, Jiří},
  title = {Low-field variation of magnetic susceptibility measured by the KLY-4S Kappabridge and KLF-4A magnetic susceptibility meter: Accuracy and interpretational programme},
  journal = {Studia Geophysica et Geodaetica},
  year = {2006},
  volume = {50},
  number = {2},
  pages = {283--299},
  url = {http://link.springer.com/10.1007/s11200-006-0016-x},
  doi = {http://dx.doi.org/10.1007/s11200-006-0016-x}
}
Verner, K., Žák, J., Hrouda, F. et al. (2006), "Magma emplacement during exhumation of the lower- to mid-crustal orogenic root: The Jihlava syenitoid pluton, Moldanubian Unit, Bohemian Massif"; Journal of Structural Geology, Vol. 28 (8) , pp. 1553-1567
Abstract: In this study, we present structural and AMS data from the ∼335 Ma ultrapotassic Jihlava syenitoid pluton, which intruded the lower- to mid-crustal orogenic root (Moldanubian Unit) in the Bohemian Massif, Central European Variscides. The emplacement of the pluton was accommodated by multiple processes, such as ductile host-rock shortening, formation of sheeted zones by magma wedging, magmatic stoping, and possibly host-rock displacement within a wide transtensional zone. Magmatic fabrics preserved in the pluton reflect both intrusive processes and regional strain. Margin-parallel and ∼ENE-WSW foliations, which probably formed by strain during emplacement of inner magma pulses, were overprinted by tectonic strain within a zone of distributed wrench-dominated dextral transtension. This zone probably accommodated exhumation of different segments in the eastern part of the Moldanubian Unit during pluton emplacement. In contrast to existing models, we emphasize that the Jihlava pluton, as well as other ultrapotassic plutons widespread in the Moldanubian Unit, are structurally highly variable bodies emplaced by multiple intrusive processes. Our case study illustrates how careful documentation of structural relations around these ultrapotassic plutons may constrain the kinematic framework and local exhumation histories in different segments of the orogenic root during and shortly after the ∼340 Ma mechanical event in the Central European Variscides. textcopyright 2006 Elsevier Ltd. All rights reserved.
BibTeX:
@article{Verner2006,
  author = {Verner, Kryštof and Žák, Jiří and Hrouda, František and Holub, František V.},
  title = {Magma emplacement during exhumation of the lower- to mid-crustal orogenic root: The Jihlava syenitoid pluton, Moldanubian Unit, Bohemian Massif},
  journal = {Journal of Structural Geology},
  year = {2006},
  volume = {28},
  number = {8},
  pages = {1553--1567},
  doi = {http://dx.doi.org/10.1016/j.jsg.2006.03.037}
}
Cifelli, F., Mattei, M., Chadima, M. et al. (2005), "The origin of tectonic lineation in extensional basins: Combined neutron texture and magnetic analyses on “undeformed” clays"; Earth and Planetary Science Letters, Vol. 235 (1-2) , pp. 62-78
Abstract: In extensional sedimentary basins fine-grained sediments that appear undeformed at the outcrop scale can carry a magnetic fabric consistent with the regional deformation pattern. The origin of the magnetic lineation, which is often found in extensional basins, is not yet well understood. In clays from extensional basins in southern Italy, the magnetic lineation is tectonically controlled and oriented perpendicular to the main normal faults. A combined analysis of magnetic and mineral fabrics was made to gain insight into the processes that lead to a lineation in extensional settings. Low-field, high-field and low-temperature susceptibility measurements were used to distinguish the ferrimagnetic and paramagnetic contributions to the magnetic susceptibility and its anisotropy. The magnetic anisotropy of the sediments is predominantly carried by paramagnetic phyllosilicates. Neutron texture analysis was used to evaluate the spatial distribution of chlorite basal planes. Results demonstrate that the orientation of the magnetic lineation is related to the spatial distribution of chlorite, lying parallel to the common axis of differently oriented basal planes. A quantitative correlation between the magnetic and rock fabric was made comparing the low- and high-field magnetic anisotropy (AMS, HFA) to the theoretical anisotropy calculated from the chlorite-preferred orientation. A good linear correlation is found between the degree of theoretical anisotropy and the AMS and HFA. Results show that the integrated approach of magnetic and mineral fabric investigations represents a valid alternative tool for detecting grain scale and regional deformation patterns in weakly deformed extensional basins, where macroscopic evidence of deformation is often not visible.
BibTeX:
@article{CIFELLI2005,
  author = {Cifelli, Francesca and Mattei, M and Chadima, Martin and Hirt, Ann M and Hansen, Anke},
  title = {The origin of tectonic lineation in extensional basins: Combined neutron texture and magnetic analyses on “undeformed” clays},
  journal = {Earth and Planetary Science Letters},
  year = {2005},
  volume = {235},
  number = {1-2},
  pages = {62--78},
  url = {http://www.sciencedirect.com/science/article/pii/S0012821X05001871},
  doi = {http://dx.doi.org/10.1016/j.epsl.2005.02.042}
}
Hrouda, F., Chlupáčová, M., Schulmann, K. et al. (2005), "On the effect of lava viscosity on the magnetic fabric intensity in alkaline volcanic rocks"; Studia Geophysica et Geodaetica, Vol. 49 (2) , pp. 191-212
Abstract: The degree of the anisotropy of magnetic susceptibility (AMS) of basaltic rocks, as is known from the large AMS database of these rocks, is generally verb, low, while in more acidic volcanic rocks such as andesites, trachytes and phonolites, which have been investigated much less frequently, it is in general much higher. In the present study, the AMS of various volcanic rocks including trachytic and phonolitic rocks was investigated in the Tertiary volcanic region of the Ceske stredohori Mts. Viscosities of the respective lavas were calculated from the chemical composition using the KWARE program. A rough correlation was found between the degree of AMS and lava viscosities, probably resulting from. different mechanisms orienting the magnetic minerals. In basaltic lava flows this mechanism is traditionally considered to be of a hydrodynamic nature, in trachytic and phonolitic bodies it can also be represented by quasi-intrusive flows resembling, at least partially, ductile flow deformation. This is in agreement with the AMS data predicted by the viscous (liquid flow) and line/plane (ductile flow) models. [References: 61]
BibTeX:
@article{Hrouda2005,
  author = {Hrouda, František and Chlupáčová, Marta and Schulmann, Karel and Šmíd, J and Závada, Prokop},
  title = {On the effect of lava viscosity on the magnetic fabric intensity in alkaline volcanic rocks},
  journal = {Studia Geophysica et Geodaetica},
  year = {2005},
  volume = {49},
  number = {2},
  pages = {191--212},
  doi = {http://dx.doi.org/10.1007/s11200-005-0005-5}
}
Žák, J., Schulmann, K. & Hrouda, F. (2005), "Multiple magmatic fabrics in the Sázava pluton (Bohemian Massif, Czech Republic): a result of superposition of wrench-dominated regional transpression on final emplacement"; Journal of Structural Geology, Vol. 27 (5) , pp. 805-822
Abstract: The Sázava pluton (∼354Ma) of the Central Bohemian Plutonic Complex was emplaced syntectonically into the upper crustal Neo-Proterozoic and Lower Paleozoic host rock along the SE margin of the Teplá-Barrandian Zone, Bohemian Massif (Czech Republic). The host rock is characterized by transpressional fabric dominated by steep SE–NW dipping foliations and subhorizontal NE–SW stretching lineations associated with flattening to a plane strain ellipsoid. The strain intensity, degree of oblateness and temperature conditions of deformation increase in the host rock towards the pluton margin. In the pluton, quartz microfabric indicates progressive cooling of the syntectonically emplaced magma. The AMS method revealed multiple magmatic fabrics and lateral variations in the shapes of the AMS ellipsoid and the magnetic fabric intensity in the pluton. The central part of the pluton yields prolate shapes of the AMS ellipsoid and a low degree of anisotropy with preserved steep magnetic lineations, whereas, along the pluton margins, oblate AMS ellipsoids are associated with a high degree of anisotropy. We interpret the multiple fabrics and the partially decoupled fabric pattern between the host rock and the pluton as being a result of superposition of regional tectonic strain during highly oblique transpression on emplacement-related intrusive strain, where outer solidified and more rigid edges of the pluton enabled preservation of older steep fabrics in its interior.
BibTeX:
@article{Zak2005,
  author = {Žák, Jiří and Schulmann, Karel and Hrouda, František},
  title = {Multiple magmatic fabrics in the Sázava pluton (Bohemian Massif, Czech Republic): a result of superposition of wrench-dominated regional transpression on final emplacement},
  journal = {Journal of Structural Geology},
  year = {2005},
  volume = {27},
  number = {5},
  pages = {805--822},
  url = {http://www.sciencedirect.com/science/article/pii/S0191814105000428},
  doi = {http://dx.doi.org/10.1016/j.jsg.2005.01.012}
}
Chadima, M., Hansen, A., Hirt, A. M. et al. (2004), "Phyllosilicate preferred orientation as a control of magnetic fabric: evidence from neutron texture goniometry and low and high-field magnetic anisotropy (SE Rhenohercynian Zone of Bohemian Massif)"; Geological Society, London, Special Publications, Vol. 238 (1) , pp. 361-380
Abstract: The low- and high-field magnetic anisotropy (AMS, HFA) of the Rhenohercynian mudstones and greywackes is compared to the theoretical anisotropy calculated from neutron texture goniometry measurements. The magnetic anisotropy is predominantly carried by the paramagnetic phyllosilicates in the form of chlorite/mica stacks and the ferromagnetic contribution is insignificant. The respective principal directions of the theoretical anisotropy and the AMS and HFA are sub-parallel; magnetic foliation reflects the orientation of the maximal concentration of phyllosilicate basal planes, magnetic lineation is subparallel to the intersection axis of those planes. For the purpose of quantitative comparison, the infrequently used standard deviatoric susceptibility as a measure of the HFA degree is employed. A very good linear correlation of the degree of theoretical anisotropy and the measured AMS and HFA is found. The prolate and oblate shapes of the respective fabric ellipsoids are reasonably well correlated. Neutron texture goniometry justifies the use of the conventional magnetic anisotropy technique for the assessment of the mineral fabric of studied rocks. When compared with other works relating the magnetic anisotropy to the mineral preferred orientation (examined by e.g. U-stage or X-ray texture goniometry) neutron texture goniometry seems to be a preferable and very precise method fabric analysis.
BibTeX:
@article{Chadima2004,
  author = {Chadima, Martin and Hansen, Anke and Hirt, Ann M and Hrouda, František and Siemes, Heinrich},
  title = {Phyllosilicate preferred orientation as a control of magnetic fabric: evidence from neutron texture goniometry and low and high-field magnetic anisotropy (SE Rhenohercynian Zone of Bohemian Massif)},
  journal = {Geological Society, London, Special Publications},
  year = {2004},
  volume = {238},
  number = {1},
  pages = {361--380},
  url = {http://sp.lyellcollection.org/cgi/doi/10.1144/GSL.SP.2004.238.01.19},
  doi = {http://dx.doi.org/10.1144/GSL.SP.2004.238.01.19}
}
Hansen, A., Chadima, M., Cifelli, F. et al. (2004), "Neutron pole figures compared with magnetic preferred orientations of different rock types"; Physica B: Condensed Matter, Vol. 350 (1-3) , pp. 120-122
Abstract: Neutron diffraction is an excellent tool for pole figure measurement of rock samples. Due to high penetration depth of neutrons for most materials neutron diffraction represents an efficient tool to measure complete pole figures with reliable grain statistics even in coarse grained or inequi-granular materials. In the field of structural geology, the measurement of anisotropy of magnetic susceptibility is a standard technique to reveal the tectonic history of deformed rocks. The application of both techniques on still ongoing studies of Precambrian, Carboniferous and Quaternary rocks which are characterised by fundamental different tectonic evolutions and mineralogical compositions shows the wide field of relevance and importance of these methods in understanding tectonic processes in detail.
BibTeX:
@article{Hansen2004,
  author = {Hansen, Anke and Chadima, Martin and Cifelli, Francesca and Brokmeier, Heinz-Günter and Siemes, Heinrich},
  title = {Neutron pole figures compared with magnetic preferred orientations of different rock types},
  journal = {Physica B: Condensed Matter},
  year = {2004},
  volume = {350},
  number = {1-3},
  pages = {120--122},
  url = {http://www.sciencedirect.com/science/article/pii/S0921452604005691},
  doi = {http://dx.doi.org/10.1016/j.physb.2004.04.008}
}
Hrouda, F. (2004), "Problems in interpreting AMS parameters in diamagnetic rocks"; Geological Society, London, Special Publications, Vol. 238 (1) , pp. 49-59
Abstract: The AMS parameters widely used to characterize the magnetic fabric of rocks (L, F, P, T) are not directly applicable to diamagnetic rocks. Namely, there are two principal methods of their definition: (1) from the signed principal susceptibilities or (2) from the absolute values of the principal susceptibilities. The first method results in L, F and P values less than one in contrast to materials whose susceptibility arises from paramagnetism and/or ferromagnetism sensu lato, where they are greater than one by definition. The ratio parameters decrease with increasing intensity of alignment of the magnetic minerals; the calculated shape parameters are, however, correct. The second method gives L, F and P values greater than one; they increase with increasing preferred orientation, however the ellipsoid shape parameters are inverse. The development of AMS parameters with increasing preferred orientation is modelled mathematically for quartzite/evaporite (para- and/or ferromagnetic AMS superimposed on the isotropic diamagnetic matrix) and for marble/limestone (preferred orientation of calcite in a rock). A rational set of AMS parameters is then recommended.
BibTeX:
@article{Hrouda2004,
  author = {Hrouda, František},
  title = {Problems in interpreting AMS parameters in diamagnetic rocks},
  journal = {Geological Society, London, Special Publications},
  year = {2004},
  volume = {238},
  number = {1},
  pages = {49--59},
  url = {http://sp.lyellcollection.org/content/238/1/49.abstract},
  doi = {http://dx.doi.org/10.1144/GSL.SP.2004.238.01.05}
}
Hrouda, F. (2004), "Magnetická anizotropie hornin a její využití ve strukturní geologii"; Čs. čas. fyz., Vol. 54 , pp. 236-239
BibTeX:
@article{Hrouda2004a,
  author = {Hrouda, František},
  title = {Magnetická anizotropie hornin a její využití ve strukturní geologii},
  journal = {Čs. čas. fyz.},
  year = {2004},
  volume = {54},
  pages = {236--239}
}
Ježek, J. & Hrouda, F. (2004), "Determination of the orientation of magnetic minerals from the anisotropy of magnetic susceptibility"; Geological Society, London, Special Publications, Vol. 238 (1) , pp. 9-20
Abstract: The anisotropy of magnetic susceptibility (AMS) of rocks is controlled by preferentially oriented magnetic mineral grains that carry AMS and, therefore, it contains information about both the grain susceptibilities and the grain orientations. Under certain conditions, information about the grain orientations can be deduced from the AMS. For a multigrain system composed of identical grains that are magnetically uniaxial (for the grain principal susceptibilities it holds that K1 > K2 = K3, or K1 = K2 > K3), an exact relationship exists between the AMS and the orientation tensor. We investigate the extent to which the theoretical relationships can be used when grains are generally triaxial. The parallelism of the principal directions of the susceptibility tensor and those of the orientation tensor are well preserved in all basic grain configurations. If grain leading axes have polar or girdle distributions and the two other axes have balanced distributions (similar orientation tensors), the parameters of intensity I and shape T based on the eigenvalues of the orientation tensor are well estimated. For unbalanced distributions, formulas are found for possible errors of I and T estimates.
BibTeX:
@article{Jezek2004,
  author = {Ježek, Josef and Hrouda, František},
  title = {Determination of the orientation of magnetic minerals from the anisotropy of magnetic susceptibility},
  journal = {Geological Society, London, Special Publications},
  year = {2004},
  volume = {238},
  number = {1},
  pages = {9--20},
  url = {http://sp.lyellcollection.org/cgi/doi/10.1144/GSL.SP.2004.238.01.02},
  doi = {http://dx.doi.org/10.1144/GSL.SP.2004.238.01.02}
}
Pokorný, J., Suza, P. & Hrouda, F. (2004), "Anisotropy of magnetic susceptibility of rocks measured in variable weak magnetic fields using the KLY-4S Kappabridge"; Geological Society, London, Special Publications , Vol. 238 (1 ) , pp. 69-76
Abstract: The theory of the anisotropy of magnetic susceptibility assumes a linear relationship between magnetization and magnetizing field, resulting in field-independent susceptibility. This relationship is valid in diamagnetic and paramagnetic minerals by definition, and also in magnetite in the fields used in common AMS meters. Pyrrhotite, hematite and titanomagnetite may show field variation of susceptibility in the same fields and therefore in principle the linear theory is incorrect for calculating the AMS. Fortunately, the linear theory nevertheless provides accurate determination of the orientations of the principal susceptibilities and of the AMS ellipsoid shape. It gives rise to inaccurate determination of the degree of AMS. Simple techniques are suggested to overcome this problem.
BibTeX:
@article{Pokorny2004,
  author = {Pokorný, Jiří and Suza, Petr and Hrouda, František},
  title = {Anisotropy of magnetic susceptibility of rocks measured in variable weak magnetic fields using the KLY-4S Kappabridge},
  journal = {Geological Society, London, Special Publications },
  year = {2004},
  volume = {238 },
  number = {1 },
  pages = {69--76},
  url = {http://sp.lyellcollection.org/content/238/1/69.abstract},
  doi = {http://dx.doi.org/10.1144/GSL.SP.2004.238.01.07}
}
Gregorová, D., Hrouda, F. & Kohút, M. (2003), "Magnetic susceptibility and geochemistry of Variscan West Carpathian granites: implications for tectonic setting"; Physics and Chemistry of the Earth, Parts A/B/C, Vol. 28 (16-19) , pp. 729-734
Abstract: Granites usually display a bimodal distribution of their magnetic susceptibility. One mode corresponds to susceptibilities of the order of 10−5–10−4 and the other one to those of the order of 10−3–10−2 [SI]. The former mode, which corresponds to ilmenite-bearing granites, is often equated with the S (sedimental) type, while the latter, which corresponds to magnetite-bearing granite, is equated with the I (igneous) type. In the West Carpathians, isotope geochemistry discriminates two groups of Variscan granites: (1) the older group (350–330 Ma) is peraluminous, from two-mica granites to granodiorites, carrying monazite and ilmenite; it resembles to common S-type and/or Ilmenite Series granite, (2) the younger group (310–300 Ma) is metaluminous to subaluminous, corresponding to biotite tonalites to granodiorites, carrying allanite and magnetite; it can be compared to the I-type and/or Magnetite Series granites. Magnetic susceptibilities of the West Carpathian granites are in general rather low, in the order of 10−4, hence corresponding to the typical values of the S type granites. A minority of specimens have susceptibilities in the order of 10−5 and a few specimens have susceptibilities higher, in the order of 10−3. This is in apparent contradiction with the granite origin as revealed geochemically. Unusual redox conditions controlled by the tectonic setting are possible explanations of this discrepancy.
BibTeX:
@article{Gregorova2003,
  author = {Gregorová, Dagmar and Hrouda, František and Kohút, Milan},
  title = {Magnetic susceptibility and geochemistry of Variscan West Carpathian granites: implications for tectonic setting},
  journal = {Physics and Chemistry of the Earth, Parts A/B/C},
  year = {2003},
  volume = {28},
  number = {16-19},
  pages = {729--734},
  url = {http://www.sciencedirect.com/science/article/pii/S1474706503001256},
  doi = {http://dx.doi.org/10.1016/S1474-7065(03)00125-6}
}
Hrouda, F., Müller, P. & Hanák, J. (2003), "Repeated progressive heating in susceptibility vs. temperature investigation: a new palaeotemperature indicator?"; Physics and Chemistry of the Earth, Parts A/B/C, Vol. 28 (16-19) , pp. 653-657
Abstract: In the most rocks, the heating segment of the curve representing the bulk magnetic susceptibility to temperature relationship is very different from the cooling segment, indicating phase and/or compositional changes imposed by heating. On the other hand, repeated run usually results in converging heating and cooling curves. It is hypothesized that the same effect may work also in the nature. Up to the temperature undergone by the rock in the nature, the heating and cooling curves should be near each other, while they should differ substantially above this temperature. If the specimen is heated repeatedly and progressively from room temperature to 700 °C, one can discover the temperature above which the heating and cooling curves start to differ substantially and identify the temperatures undergone by the rock in the nature.
BibTeX:
@article{Hrouda2003,
  author = {Hrouda, František and Müller, P and Hanák, Jaromír},
  title = {Repeated progressive heating in susceptibility vs. temperature investigation: a new palaeotemperature indicator?},
  journal = {Physics and Chemistry of the Earth, Parts A/B/C},
  year = {2003},
  volume = {28},
  number = {16-19},
  pages = {653--657},
  url = {http://www.sciencedirect.com/science/article/pii/S1474706503001190},
  doi = {http://dx.doi.org/10.1016/S1474-7065(03)00119-0}
}
Kratinová, Z., Schulmann, K., Hrouda, F. et al. (2003), "The role of regional tectonics and magma flow coupling versus magmatic processes in generating contrasting magmatic fabrics within the land's end granite, Cornwall"; , Vol. 10 (4)Geoscience in South-West England , pp. 442-448
Abstract: The Lower Permian Land's End Granite intruded Upper Devonian metasedimentary and metavolcanic rocks of the Mylor Slate Formation that had been previously deformed and regionally metamorphosed during Variscan convergence. Structural studies of the host rocks have been used to infer that granite generation and emplacement occurred in response to regional D3 NNW-SSE extension of moderately thickened crust. Detailed field mapping along the northwestern margin of the granite reveals complex magmatic fabrics defined by K-feldspar and biotite. Close to the pluton margins, a gently NW or SE dipping magmatic foliation is defined by the preferred orientation of K-feldspar and biotite. Further from the pluton margin, the foliation dips moderately NW or SE, or occurs in steeply dipping NW-SE trending zones with very strong fabrics. Magmatic foliations tend towards parallelism with the margins of stoped blocks over a distance of one to several metres, but there is no evidence that the blocks deform a previously formed magmatic fabric. The Land's End Granite exhibits low degrees of anisotropy of magnetic susceptibility (AMS) and biotite is the carrier. The AMS foliation generally dips gently to the NW or SE and contains two, near-orthogonal lineations that trend ENEWSW and N-S. The variations in magnetic lineation orientation correlate with the intensity of the macroscopic feldspar fabric. In zones where the feldspar fabric is strongly developed, the AMS has a NW plunging lineation, whereas in zones where the feldspar fabric is weak, the AMS has a NE plunging lineation. There is close correspondence between the orientation of the AMS fabrics and D3 structures within the Mylor Slate Formation. However, it is possible that there was only partial coupling between the granite magma and extensional deformation of the host rock. Stoped blocks and host rock irregular contacts exert a significant control on fabric orientation.
BibTeX:
@inproceedings{Kratinova2003,
  author = {Kratinová, Zuzana and Schulmann, Karel and Hrouda, František and Shail, R. K.},
  title = {The role of regional tectonics and magma flow coupling versus magmatic processes in generating contrasting magmatic fabrics within the land's end granite, Cornwall},
  booktitle = {Geoscience in South-West England},
  year = {2003},
  volume = {10},
  number = {4},
  pages = {442--448}
}
Hrouda, F. (2003), "Indices for Numerical Characterization of the Alteration Processes of Magnetic Minerals Taking Place During Investigation of Temperature Variation of Magnetic Susceptibility"; Studia Geophysica et Geodaetica, Vol. 47 (4) , pp. 847-861
Abstract: The alteration of magnetic minerals taking place during the investigation of the temperature variation of bulk magnetic susceptibility is obvious from different courses of heating and cooling susceptibility vs. temperature curves. A set of indices is introduced to characterize these changes numerically. The A 40 alteration index characterizes the change in susceptibility after executing the whole cycle of heating and cooling. The maximum difference between the heating and cooling curves is characterized by the A max alteration index. The mean or average difference between the heating and cooling curves is characterized by the A m alteration index. The situation whether the heating and cooling curves cross, is characterized by the A cr alteration index. The technique of progressive repeated heating is proposed, together with the above indices, to locate the temperature intervals with weak and strong magnetic mineral changes induced by heating.
BibTeX:
@article{ref1,
  author = {Hrouda, František},
  title = {Indices for Numerical Characterization of the Alteration Processes of Magnetic Minerals Taking Place During Investigation of Temperature Variation of Magnetic Susceptibility},
  journal = {Studia Geophysica et Geodaetica},
  year = {2003},
  volume = {47},
  number = {4},
  pages = {847--861},
  url = {http://link.springer.com/10.1023/A:1026398920172},
  doi = {http://dx.doi.org/10.1023/A:1026398920172}
}
Hrouda, F. (2002), "Low-field variation of magnetic susceptibility and its effect on the anisotropy of magnetic susceptibility of rocks"; Geophysical Journal International, Vol. 150 (3) , pp. 715-723, Blackwell Science Ltd
Abstract: The theory of the low-field anisotropy of magnetic susceptibility (AMS) assumes a linear relationship between magnetization and the magnetizing field. This assumption is precisely valid in diamagnetic and paramagnetic minerals by definition, while in ferrimagnetic and antiferromagnetic minerals this relationship is in general non-linear (represented by a hysteresis loop), being linear only with very weak fields in which the initial susceptibility is measured. Recently, it has been shown that, in using common measuring fields, the field-independent susceptibility is measured in magnetite, while in pyrrhotite, haematite and titanomagnetite it may often be outside the initial susceptibility range. The problem can be solved in three ways. The simplest way is using very weak measuring fields (less than 10 A m−1), but this can result in significant lowering of sensitivity and precision. The second way is to respect the non-linearity and measure the susceptibility in so many directions that contour diagram of directional susceptibilities can be presented instead of a susceptibility ellipsoid. The third way is to measure the AMS within the Rayleigh law range and calculate the initial directional susceptibilities from which the AMS can be correctly determined using linear theory.
BibTeX:
@article{GJI:GJI1731,
  author = {Hrouda, František},
  title = {Low-field variation of magnetic susceptibility and its effect on the anisotropy of magnetic susceptibility of rocks},
  journal = {Geophysical Journal International},
  publisher = {Blackwell Science Ltd},
  year = {2002},
  volume = {150},
  number = {3},
  pages = {715--723},
  url = {http://doi.wiley.com/10.1046/j.1365-246X.2002.01731.x},
  doi = {http://dx.doi.org/10.1046/j.1365-246X.2002.01731.x}
}
Hrouda, F., Plasienska, D. & Gregorová, D. (2002), "Assumed Neogene deformation in the Central West Carpathians inferred from magnetic anisotropy investigations"; EGS Stephan Mueller Publication Series, Vol. 1 , pp. 195-211
BibTeX:
@article{Hrouda2002,
  author = {Hrouda, František and Plasienska, D and Gregorová, Dagmar},
  title = {Assumed Neogene deformation in the Central West Carpathians inferred from magnetic anisotropy investigations},
  journal = {EGS Stephan Mueller Publication Series},
  year = {2002},
  volume = {1},
  pages = {195--211},
  url = {http://www.stephan-mueller-spec-publ-ser.net/1/125/2002/smsps-1-125-2002.pdf}
}
Hrouda, F. (2002), "The use of the anisotropy of magnetic remanence in the resolution of the anisotropy of magnetic susceptibility into its ferromagnetic and paramagnetic components"; Tectonophysics, Vol. 347 (4) , pp. 269-281
Abstract: The anisotropy of magnetic susceptibility (AMS) is often controlled by both ferromagnetic (sensu lato) and paramagnetic minerals. The anisotropy of magnetic remanence (AMR) is solely controlled by ferromagnetic minerals. Jelı́nek (Trav. Geophys. 37 (1993)) introduced a tensor derived from the isothermal AMR whose normalized form equals the normalized susceptibility tensor provided that the ferromagnetic fraction is represented by multi-domain magnetite. The present paper shows the close correlation between these tensors for a collection of strongly magnetic specimens containing multi-domain magnetite. In addition, acceptable correlation between the tensors was also found for a collection of specimens containing single-domain magnetite. A new method is developed for the AMS resolution into ferromagnetic and paramagnetic components using the AMR. Some examples are presented of this resolution in mafic microgranular enclaves in granodiorite and in gneisses of the KTB borehole.
BibTeX:
@article{Hrouda2002,
  author = {Hrouda, František},
  title = {The use of the anisotropy of magnetic remanence in the resolution of the anisotropy of magnetic susceptibility into its ferromagnetic and paramagnetic components},
  journal = {Tectonophysics},
  year = {2002},
  volume = {347},
  number = {4},
  pages = {269--281},
  url = {http://www.sciencedirect.com/science/article/pii/S0040195102000756},
  doi = {http://dx.doi.org/10.1016/S0040-1951(02)00075-6}
}
Hrouda, F., Chlupáčová, M. & Novák, J. K. (2002), "Variations in magnetic anisotropy and opaque mineralogy along a kilometer deep profile within a vertical dyke of the syenogranite porphyry at Cı́novec (Czech Republic)"; Journal of Volcanology and Geothermal Research, Vol. 113 (1-2) , pp. 37-47
Abstract: Vertical variations in magnetic fabric and paragenesis of the ferrimagnetic minerals for a virtually upright dyke of the Altenberg syenogranite porphyry were investigated using profile data of borehole E-16 to a depth of 922.7 m (Eastern Krušné hory Mts., NW Bohemia). It was revealed that this dyke likely consists of two magma pulses indicated both by magnetic fabric and by opaque mineralogy. In most of the profile, the magnetite grains are oriented parallel to the sub-vertical dyke. Only at the base of the upper magma pulse, in a depth interval of 200–400 m, are these grains oriented sub-horizontally being thus perpendicular to the dyke walls. This pattern can be interpreted as a consequence of a static vertical compaction of the magma of the basal portions of the upper pulse due to the pressure of the ascending lower pulse. The large planes of the ferrimagnetic minerals are oriented perpendicular to the shortening direction.
BibTeX:
@article{Hrouda2002a,
  author = {Hrouda, František and Chlupáčová, Marta and Novák, Jiří K},
  title = {Variations in magnetic anisotropy and opaque mineralogy along a kilometer deep profile within a vertical dyke of the syenogranite porphyry at Cı́novec (Czech Republic)},
  journal = {Journal of Volcanology and Geothermal Research},
  year = {2002},
  volume = {113},
  number = {1-2},
  pages = {37--47},
  url = {http://www.sciencedirect.com/science/article/pii/S0377027301002499},
  doi = {http://dx.doi.org/10.1016/S0377-0273(01)00249-9}
}
Hrouda, F., Putiš, M. & Madarás, Já. (2002), "The Alpine overprints of the magnetic fabrics in the basement and cover rocks of the Veporic Unit (Western Carpathians, Slovakia)"; Tectonophysics, Vol. 359 (3-4) , pp. 271-288
Abstract: In the Veporic Unit building up the central areas of the Western Carpathians, the magnetic fabrics are more or less coplanar and coaxial in metamorphic (Early Palaeozoic in age), granitic (Early to Late Palaeozoic in age) and sedimentary cover rocks (Permian/Triassic in age). The magnetic fabrics in metamorphic and granitoid basement rocks, as well as in sedimentary (-volcanic) cover rocks, appear to reflect a very wide P–T conditions of Cretaceous (originally Variscan) basement reactivation connected with a prograde metamorphism of the sedimentary cover rocks in lower greenschist (in the North-Veporic area) or the upper greenschist to lower amphibolite facies (in the South-Veporic area) during collisional burial in a collisional wedge. In addition, there are deformation zones where the magnetic fabrics formed due to a ductile deformation associated with extensional exhumation along (sinistral) lateral strike slip and normal faults. The late open folds did not principally change the former magnetic fabrics. The magnetic fabrics in sedimentary cover rocks of the North-Veporic area are either related to still recognizable bedding planes (in competent layers) with parallel superimposed metamorphic schistosity, or they are conformable to subparallel or oblique metamorphic cleavages. In the South-Veporic area, they are undoubtedly related to the metamorphic–mylonitic fabrics of the basement granitoids and their metamorphic mantle rocks. The magnetic fabrics in granitoid rocks of the South-Veporic area (S of the Pohorelá sinistral strike-slip fault) are influenced with micromechanisms of dominated low-temperature ductile deformation and partial dynamic recrystallization. We ascribe the observed coaxial magnetic fabrics in metamorphic, granitic and sedimentary rocks to an Alpine collision (110–95 Ma; Pmax∼8–9 kbar, Tmax∼530 °C) and extension tectonometamorphic events (95–80 Ma; up to P∼4–5 kbar, T∼300 °C) of Cretaceous age. The magnetic fabrics seem not to be strongly dependent on temperatures until the medium part of the amphibolite facies (as in this example), but they are strongly following simultaneous deformational low-temperature to medium-temperature meso- and microfabrics.
BibTeX:
@article{Hrouda2002b,
  author = {Hrouda, František and Putiš, Marián and Madarás, Ján},
  title = {The Alpine overprints of the magnetic fabrics in the basement and cover rocks of the Veporic Unit (Western Carpathians, Slovakia)},
  journal = {Tectonophysics},
  year = {2002},
  volume = {359},
  number = {3-4},
  pages = {271--288},
  url = {http://www.sciencedirect.com/science/article/pii/S0040195102005152},
  doi = {http://dx.doi.org/10.1016/S0040-1951(02)00515-2}
}
Ježek, J. & Hrouda, F. (2002), "Software for modeling the magnetic anisotropy of strained rocks"; Computers & Geosciences, Vol. 28 (9) , pp. 1061-1068
Abstract: The anisotropy of magnetic susceptibility is controlled by the preferred orientation of magnetic minerals in rocks and may be significantly influenced by deformation. This allows us to replace difficult estimation of strain parameters by indirect anisotropy of magnetic susceptibility (AMS) measurements. The interpretation of AMS is based on observation experience and modeling the AMS to strain relationship. The modeling is complex due to the large number of input parameters: different carriers of magnetism and their magnetic properties, their initial orientation distribution, the manner in which the deformation influences the reorientation of magnetic carriers, the character and duration of deformation. These parameters are taken into account in the presented package of Matlab functions for modeling AMS of strained rocks. The functions can be freely combined by the user to cover all basic types of homogeneous deformation (simple shear, pure shear, plane strain, coaxial deformation, transpression). A procedure is presented to treat the example of inhomogeneous deformation.
BibTeX:
@article{Jezek2002,
  author = {Ježek, Josef and Hrouda, František},
  title = {Software for modeling the magnetic anisotropy of strained rocks},
  journal = {Computers & Geosciences},
  year = {2002},
  volume = {28},
  number = {9},
  pages = {1061--1068},
  url = {http://www.sciencedirect.com/science/article/pii/S0098300402000237},
  doi = {http://dx.doi.org/10.1016/S0098-3004(02)00023-7}
}
Ježek, J. & Hrouda, F. (2002), "A technique for numerical modeling of magnetic anisotropy to strain relationship"; Physics and Chemistry of the Earth, Parts A/B/C, Vol. 27 (25-31) , pp. 1247-1252
Abstract: The anisotropy of magnetic susceptibility (AMS) is controlled by the preferred orientation of magnetic minerals in rocks which may be significantly influenced by deformation. This allows us to replace difficult estimation of strain parameters by indirect AMS measurements and the interpretation based on the models of AMS to strain relation. The nature of recently used models is rather simple but the modeling itself is necessarily complex due to large number of input parameters: different carriers of magnetism and their magnetic properties, their initial distribution, the manner how the deformation influences reorientation of magnetic carriers, the character and duration of deformation. A technique is presented for numerical modeling simultaneous temporal evolution of strain and AMS, taking into account these parameters. The presentation of computing procedure is accompanied by an example. A Matlab program for modeling can be obtained on request from authors.
BibTeX:
@article{Jezek2002a,
  author = {Ježek, Josef and Hrouda, František},
  title = {A technique for numerical modeling of magnetic anisotropy to strain relationship},
  journal = {Physics and Chemistry of the Earth, Parts A/B/C},
  year = {2002},
  volume = {27},
  number = {25-31},
  pages = {1247--1252},
  url = {http://www.sciencedirect.com/science/article/pii/S1474706502001183},
  doi = {http://dx.doi.org/10.1016/S1474-7065(02)00118-3}
}
Ježek, J. & Hrouda, F. (2002), "Software for modeling the magnetic anisotropy of strained rocks"; Computers & Geosciences, Vol. 28 (9) , pp. 1061-1068
Abstract: The anisotropy of magnetic susceptibility is controlled by the preferred orientation of magnetic minerals in rocks and may be significantly influenced by deformation. This allows us to replace difficult estimation of strain parameters by indirect anisotropy of magnetic susceptibility (AMS) measurements. The interpretation of AMS is based on observation experience and modeling the AMS to strain relationship. The modeling is complex due to the large number of input parameters: different carriers of magnetism and their magnetic properties, their initial orientation distribution, the manner in which the deformation influences the reorientation of magnetic carriers, the character and duration of deformation. These parameters are taken into account in the presented package of Matlab functions for modeling AMS of strained rocks. The functions can be freely combined by the user to cover all basic types of homogeneous deformation (simple shear, pure shear, plane strain, coaxial deformation, transpression). A procedure is presented to treat the example of inhomogeneous deformation. textcopyright 2002 Elsevier Science Ltd. All rights reserved.
BibTeX:
@article{Jezek2002b,
  author = {Ježek, Josef and Hrouda, František},
  title = {Software for modeling the magnetic anisotropy of strained rocks},
  journal = {Computers & Geosciences},
  year = {2002},
  volume = {28},
  number = {9},
  pages = {1061--1068},
  url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-0036871022&partnerID=tZOtx3y1},
  doi = {http://dx.doi.org/10.1016/S0098-3004(02)00023-7}
}
Crick, R. E., Ellwood, B. B., Hladil, J. et al. (2001), "Magnetostratigraphy susceptibility of the Přídolian-Lochkovian (Silurian-Devonian) GSSP (Klonk, Czech Republic) and a coeval sequence in anti-atlas Morocco"; Palaeogeography, Palaeoclimatology, Palaeoecology, Vol. 167 (1-2) , pp. 73-100
Abstract: The magnetosusceptibility event and cyclostratigraphy (MSEC) record for the Přídolian-Lochkovian (Silurian-Devonian) Global Boundary Stratotype Section and Point (GSSP) (Klonk, Prague Basin, Czech Republic) is described and used to establish a magnetostratigraphy susceptibility profile for the GSSP. GSSP MSEC data are summarized into three magnetozones (MSZ). The Tmaň MSZ (Late Přídolian) with 13 MSSZs (MSSZ), the Klonk MSZ (latest Přídolian and earliest Lochkovian) with 17 MSSZs, and the Voskop MSZ (Early Lochkovian) with 7 MSSZs. The base of Klonk MSSZ 2 is coincident with the base of Lochkovian and the Devonian. The proposed magnetostratotype for the Přídolian-Lochkovian boundary is supported by MS data from a nearby core through the GSSP sequence and into the upper Ludlow. Three additional MSZs are recognized for the portion of the core sequence older than the GSSP boundary sequence. The extension of the MSZs and MSSZs away from the proposed magnetostratotype is tested by comparison with a Lochkovian sequence in the western Sahara of southeastern Morocco. MSZs are the result of global sea level fluctuations that alter base level and the pattern of erosion and influx of detrital paramagnetic mineral components into the marine environment. Large-scale transgressive and regressive patterns interpreted from the MSEC data establish that the Silurian-Devonian boundary in the Barrandian region falls between a short-lived transgressive pulse in the latest Přídolian and an equally short-lived regressive pulse in the earliest Lochkovian. MSSZs identified in the GSSP and core sequences are the result of variation in climate cycles and the resulting periodicity can explained by either the 38.9 Ka Silurian and Devonian equivalent of the modern 54 Ka obliquity cycle or the eccentricity cycle of 106 Ka periodicity. Use of the obliquity periodicity gives a duration for the Barrandian Lochkovian of 4.46 Ma which agrees with the most recent geochronometric estimate of 4.5 Ma for the Lochkovian. Use of the eccentricity periodicity gives a duration for the Barrandian Lochkovian of 12.16 Ma which agrees with the previous geochronometric estimates of 12.2 and 12.5 Ma for the Lochkovian. In any case the cyclic nature of the MSEC data established by the MSSZs can be explained by variations in the rate of supply of weathered terrigenous paramagnetic grains to the marine system. These variations in supply occurred due to climate changes resulting from the either the obliquity or eccentricity of the Earth's orbit. Knowledge of the periodicity of Lochkovian cycles in the Barrandian area allows estimation of the rates of sediment accumulation, the duration of fossil ranges, and the rates of evolution. Depending on the choice of obliquity or eccentricity to explain the cyclicity in the Barrandian Lochkovian, the estimated rate of sediment accumulation in the GSSP outcrop averaged either 51 or 140 Ka/m. The range of the graptoloid Monograptus uniformis angustidens, wholly contained within the Lochkovian sequence at the GSSP, is also estimated at either 51 or 140 Ka. textcopyright 2001 Elsevier Science B.V.
BibTeX:
@article{Crick2001,
  author = {Crick, R. E. and Ellwood, Brooks B and Hladil, J. and El Hassani, A. and Hrouda, František and Chlupáč, I},
  title = {Magnetostratigraphy susceptibility of the Přídolian-Lochkovian (Silurian-Devonian) GSSP (Klonk, Czech Republic) and a coeval sequence in anti-atlas Morocco},
  journal = {Palaeogeography, Palaeoclimatology, Palaeoecology},
  year = {2001},
  volume = {167},
  number = {1-2},
  pages = {73--100},
  doi = {http://dx.doi.org/10.1016/S0031-0182(00)00233-9}
}
Hrouda, F. & Ullemayer, K. (2001), "Quantitative correlation of biotite lattice preferred orientations and magnetic fabrics in granulites from the Southern Bohemian Massif"; Z. dt. Geol. Ges., Vol. 152 , pp. 547-561
Abstract: Anisotropy of magnetic susceptibility (AMS) of most rocks is controlled by the paramag- netic (micas) and ferromagnetic (ore minerals) rock constituents.AMS and biotite preferred orien- tation measurements were performed on granulites from the Southern Bohemian Massif, which are characterized by a complicated deformation his- tory.The deconvolution of the measured rock AMS led to an extremely prolate ferromagnetic compo- nent of the AMS, whereas the bulk rock AMS as well as the separated paramagnetic AMS are oblate in all cases. The paramagnetic AMS can be clearly related to biotite, whereas the carriers of the ferro- magnetic AMS are still unknown. It seems that sub- microscopic ore minerals predominate and the optically visible ore minerals play a minor role.The performed measurements also confirm that the fer- romagnetic AMS component should not be neglect- ed,even in low susceptible rocks.
BibTeX:
@article{Hrouda2001,
  author = {Hrouda, František and Ullemayer, K},
  title = {Quantitative correlation of biotite lattice preferred orientations and magnetic fabrics in granulites from the Southern Bohemian Massif},
  journal = {Z. dt. Geol. Ges.},
  year = {2001},
  volume = {152},
  pages = {547--561},
  url = {https://www.google.cz/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&cad=rja&uact=8&ved=0ahUKEwi5leqvsNnKAhVBcA8KHUbLCq8QFggeMAA&url=http://www.schweizerbart.de/content/papers_preview/download/80445&usg=AFQjCNEBlJNuoQL-baMfxGxJjk5VdW5Wug&sig2=SKvn},
  doi = {http://dx.doi.org/10.1127/zdgg/152/2001/547}
}
Hrouda, F., Hanák, J. & Terzijski, I. (2000), "The magnetic and pore fabrics of extruded and pressed ceramic models"; Geophysical Journal International, Vol. 142 (3) , pp. 941-947
Abstract: Ceramics were used as a model to investigate the pore fabric originated during ductile deformation. The magnetic anisotropy was used to measure the pore fabric after pore saturation by a ferromagnetic fluid. The ductile deformation of the ceramics was investigated by measuring the magnetic anisotropy of dry specimens. The character and symmetry of the pore fabric are compatible with those of the deformations forming the fabric of the ceramics: in the linearly extruded ceramics, the pore fabric is dominantly prolate, while in the pressed ceramics it is dominantly oblate.
BibTeX:
@article{Hrouda2000,
  author = {Hrouda, František and Hanák, Jaromír and Terzijski, Ivajlo},
  title = {The magnetic and pore fabrics of extruded and pressed ceramic models},
  journal = {Geophysical Journal International},
  year = {2000},
  volume = {142},
  number = {3},
  pages = {941--947},
  url = {http://gji.oxfordjournals.org/content/142/3/941.abstract},
  doi = {http://dx.doi.org/10.1046/j.1365-246x.2000.00216.x}
}
Hrouda, F., Krejčí, O. & Otava, J. (2000), "Magnetic fabric in folds of the easternmost Rheno-Hercynian Zone"; Physics and Chemistry of the Earth, Part A: Solid Earth and Geodesy, Vol. 25 (5) , pp. 505-510
Abstract: The magnetic fabric in folds was investigated in the easternmost Rheno-Hercynian Zone, the Nízký Jeseník Mts. In their eastern areas, the rocks show signs of only weak achimetamorphism and very gentle ductile deformation; SE vergent buckle folds of long wavelength are developed whose magnetic fabric can be easily unfolded geometrically. In the central areas, spaced cleavage and NW vergent buckle folds can be found; the folds can be unfolded mostly only partially. In the western areas, NW vergent cleavage folds and very well developed slaty cleavage occur. The magnetic fabric in the folds is homogeneous, the folds cannot be unfolded at all. The cleavage is transformed into metamorphic schistosity at the western border of the area.
BibTeX:
@article{Hrouda2000,
  author = {Hrouda, František and Krejčí, Oldřich and Otava, Jiří},
  title = {Magnetic fabric in folds of the easternmost Rheno-Hercynian Zone},
  journal = {Physics and Chemistry of the Earth, Part A: Solid Earth and Geodesy},
  year = {2000},
  volume = {25},
  number = {5},
  pages = {505--510},
  url = {http://www.sciencedirect.com/science/article/pii/S1464189500000788},
  doi = {http://dx.doi.org/10.1016/S1464-1895(00)00078-8}
}
Hrouda, F., Henry, B. & Borradaile, G. (2000), "Limitations of tensor subtraction in isolating diamagnetic fabrics by magnetic anisotropy"; Tectonophysics, Vol. 322 (3-4) , pp. 303-310
Abstract: The anisotropy of low field susceptibility (AMS) represents the orientation distribution of all minerals in a rock, whereas the anisotropy of magnetic remanence (AMR, preferably anhysteretic) isolates that of the accessory remanence-bearing minerals. The subtraction of normalized AMR from AMS, in theory and under limited practical circumstances, may isolate the paramagnetic+diamagnetic anisotropy contribution and thus the orientation distribution of the matrix minerals (Borradaile et al., 1999. Geol. Soc. Lond., Sp. Publ. 151, 139–145). Limitations include the great sensitivity of the subtraction process to the precision of the definition of the respective (AMS, AMR) tensors, and a requirement that single-domain and superparamagnetic grains are absent. The latter is particularly important for superparamagnetic minerals because iron oxides may be part of the orientation distribution of the main group of remanence-bearing minerals, although they would be excluded from the AMR fabric. Low ratios of saturation isothermal remanence to induced susceptibility characterize those rare rocks in which superparamagnetic behavior is a significant contribution.
BibTeX:
@article{Hrouda2000a,
  author = {Hrouda, František and Henry, Bernard and Borradaile, Graham},
  title = {Limitations of tensor subtraction in isolating diamagnetic fabrics by magnetic anisotropy},
  journal = {Tectonophysics},
  year = {2000},
  volume = {322},
  number = {3-4},
  pages = {303--310},
  url = {http://www.sciencedirect.com/science/article/pii/S0040195100000937},
  doi = {http://dx.doi.org/10.1016/S0040-1951(00)00093-7}
}
Ježek, J. & Hrouda, F. (2000), "The relationship between the Lisle orientation tensor and the susceptibility tensor"; Physics and Chemistry of the Earth, Part A: Solid Earth and Geodesy, Vol. 25 (5) , pp. 469-474
Abstract: Lisle (1989) introduced an orientation tensor of orthogonal orientation data as summed cross products of the direction cosines of the X axes minus the summed cross products of the direction cosines of the Z axes. The contribution deals with the relationship between the Lisle orientation tensor and the tensor of magnetic susceptibility. The bulk magnetic susceptibility is generated by a system of triaxial magnetic grains. In the case of “ideally” triaxial magnetic grains, the eigenvectors of the tensor of Lisle are parallel to the eigenvectors of magnetic susceptibility, and in the case of general triaxial grains they are close to them. Analytical results and numerical modelling confirm the intuitive feeling that AMS of a system composed of triaxial magnetic grains reflects the mean orientation of X as well as Z grain axes.
BibTeX:
@article{Jezek2000,
  author = {Ježek, Josef and Hrouda, František},
  title = {The relationship between the Lisle orientation tensor and the susceptibility tensor},
  journal = {Physics and Chemistry of the Earth, Part A: Solid Earth and Geodesy},
  year = {2000},
  volume = {25},
  number = {5},
  pages = {469--474},
  url = {http://www.sciencedirect.com/science/article/pii/S1464189500000727 http://linkinghub.elsevier.com/retrieve/pii/S1464189500000727},
  doi = {http://dx.doi.org/10.1016/S1464-1895(00)00072-7}
}
Hrouda, F., Táborská, Š., Schulmann, K. et al. (1999), "Magnetic fabric and rheology of co-mingled magmas in the Nasavrky Plutonic Complex (E Bohemia): implications for intrusive strain regime and emplacement mechanism"; Tectonophysics, Vol. 307 (1-2) , pp. 93-111
Abstract: The fabrics of mafic microgranular enclaves (MME) and of the host granodiorite of the old granodiorite intrusion of the Nasavrky Plutonic Complex (E Bohemia) were investigated by means of magnetic anisotropy. The magnetic fabric in MME is oriented coaxially with the magnetic fabric of the host granodiorite which is undoubtedly magmatic (intrusive) in origin. Consequently, the magnetic fabric in MME originated during the same process as the magnetic fabric in granodiorite, i.e. during the granodiorite emplacement. In addition, also the degree of anisotropy and the shapes of susceptibility ellipsoids are very similar in MME and in granodiorite, which probably indicates that the MME had probably a similar viscosity to that of granodiorite and behaved as passive markers whose shapes resembled those of the intrusive strain ellipsoids. Petrological and geochemical approaches coupled with rheological modelling allow the prediction of the physical states of magmas and of the development of their internal fabrics. Observed fabrics were compared to the results of numerical modelling of multiparticle systems slowly moving in viscous fluid. The steep magnetic foliations and almost vertical magnetic lineations suggest that today's erosion level represents a relatively deep intrusive level where magma flowed vertically and its intrusion was controlled by the shape of the feeder zone used for magma ascension.
BibTeX:
@article{Hrouda1999,
  author = {Hrouda, František and Táborská, Štěpánka and Schulmann, Karel and Ježek, Josef and Dolejš, David},
  title = {Magnetic fabric and rheology of co-mingled magmas in the Nasavrky Plutonic Complex (E Bohemia): implications for intrusive strain regime and emplacement mechanism},
  journal = {Tectonophysics},
  year = {1999},
  volume = {307},
  number = {1-2},
  pages = {93--111},
  url = {http://www.sciencedirect.com/science/article/pii/S0040195199001213},
  doi = {http://dx.doi.org/10.1016/S0040-1951(99)00121-3}
}
Hrouda, F. & Ježek, J. (1999), "Theoretical models for the relationship between magnetic anisotropy and strain: effect of triaxial magnetic grains"; Tectonophysics, Vol. 301 (3-4) , pp. 183-190
Abstract: The movements of individual triaxial particles in some models of deformed rocks are in general much more complex than the movements of spheroidal particles. However, the presented magnetic anisotropy to strain models considering multiparticle systems of triaxial magnetic particles show very similar results to the models that consider a mixture of prolate and oblate spheroidal particles. We explain this observation by assuming that even though the movements of individual triaxial particles are very complex, the multiparticle system as a whole `averages out' in some way the movements, and the resulting magnetic anisotropy tensor does not differ very much from the tensor of the model considering a mixture of prolate and oblate spheroids. The magnetic anisotropy vs. strain models are therefore much more robust than the standard fabric vs. strain models.
BibTeX:
@article{Hrouda1999,
  author = {Hrouda, František and Ježek, Josef},
  title = {Theoretical models for the relationship between magnetic anisotropy and strain: effect of triaxial magnetic grains},
  journal = {Tectonophysics},
  year = {1999},
  volume = {301},
  number = {3-4},
  pages = {183--190},
  url = {http://www.sciencedirect.com/science/article/pii/S0040195198002674 http://linkinghub.elsevier.com/retrieve/pii/S0040195198002674},
  doi = {http://dx.doi.org/10.1016/S0040-1951(98)00267-4}
}
Hrouda, F. & Ježek, J. (1999), "Magnetic anisotropy indications of deformations associated with diagenesis"; , Vol. 151 Palaeomagnetism and Diagenesis in Sediments , pp. 127-137, Geological Society, London
BibTeX:
@inbook{Hrouda1999a,
  author = {Hrouda, František and Ježek, Josef},
  title = {Magnetic anisotropy indications of deformations associated with diagenesis},
  booktitle = {Palaeomagnetism and Diagenesis in Sediments},
  publisher = {Geological Society, London},
  year = {1999},
  volume = {151},
  pages = {127--137}
}
Hrouda, F., Hanák, J. & Terzijski, I. (1999), "Pore fabrics of ceramic models investigated by magnetic anisotropy"; Physics and Chemistry of the Earth, Part A: Solid Earth and Geodesy, Vol. 24 (7) , pp. 607-610
Abstract: Ceramics was used as model to investigate the pore fabric originated during ductile deformation. The magnetic anisotropy was used to measure the connected pore fabric after pore saturating by the ferromagnetic fluid. The ductile deformation of the ceramics was investigated through measurement of magnetic anisotropy of dry specimens. The character and symmetry of the pore fabric are compatible with those of the deformations forming the fabric of the ceramics.
BibTeX:
@article{Hrouda1999a,
  author = {Hrouda, František and Hanák, Jaromír and Terzijski, Ivajlo},
  title = {Pore fabrics of ceramic models investigated by magnetic anisotropy},
  journal = {Physics and Chemistry of the Earth, Part A: Solid Earth and Geodesy},
  year = {1999},
  volume = {24},
  number = {7},
  pages = {607--610},
  url = {http://www.sciencedirect.com/science/article/pii/S1464189599000873},
  doi = {http://dx.doi.org/10.1016/S1464-1895(99)00087-3}
}
Hrouda, F. & Ježek, J. (1999), "Magnetic anisotropy indications of deformations associated with diagenesis"; , Palaeomagnetism and Diagenesis in Sediments , pp. 127-138, The Geological Society
Abstract: This paper is part of the special publication No.151, Palaeomagnetism and diagenesis in sediments (eds D.H. Harling and P. Turner). Anisotropy of magnetic susceptibility (AMS), as revealed by mathematical modelling and empirical studies, sensitively reflects initial ductile deformation associated with diagenesis and early tectonism. In rocks shortened vertically because of the gravitational loading by the weight of overlying strata, the degree of AMS increases and the magnetic fabric becomes more oblate. The magnetic foliation remains parallel to the bedding and the magnetic lineation remains near the water current directions. In rocks shortened laterally, usually by tectonic forces, the degree of AMS and the magnetic fabric oblateness initially decrease and only later increase. The magnetic lineation deflects from the water current direction and the magnetic foliation from the bedding, with its poles creating a girdle pattern. The AMS changes are due to the physical rotation of magnetic grains, which has serious implications for palaeomagnetism, but are major indicators of the change from a diagenetic to a tectonically controlled regime.
BibTeX:
@book{tarling1999palaeomagnetism,
  author = {Hrouda, František and Ježek, Josef},
  title = {Magnetic anisotropy indications of deformations associated with diagenesis},
  booktitle = {Palaeomagnetism and Diagenesis in Sediments},
  publisher = {The Geological Society},
  year = {1999},
  pages = {127--138},
  url = {https://books.google.cz/books?id=rNt0o81p7_YC}
}
Kapička, A., Petrovský, E., Hrouda, F. et al. (1998), "Changes in magnetic parameters of rocks under pressure conditions of the Earth's crust: relationship to magnetic mineralogy"; Rev. High Pressure Sci. Technol., Vol. 7 , pp. 69-71
BibTeX:
@article{Kapicka1998,
  author = {Kapička, Aleš and Petrovský, Eduard and Hrouda, František and Pohl, J},
  title = {Changes in magnetic parameters of rocks under pressure conditions of the Earth's crust: relationship to magnetic mineralogy},
  journal = {Rev. High Pressure Sci. Technol.},
  year = {1998},
  volume = {7},
  pages = {69--71}
}
Eyre, J. K. (1997), "Frequency dependence of magnetic susceptibility for populations of single-domain grains"; Geophysical Journal International, Vol. 129 (1) , pp. 209-211
BibTeX:
@article{doi:10.1111/j.1365-246X.1997.tb00951.x,
  author = {Eyre, John K},
  title = {Frequency dependence of magnetic susceptibility for populations of single-domain grains},
  journal = {Geophysical Journal International},
  year = {1997},
  volume = {129},
  number = {1},
  pages = {209--211},
  url = {+ http://dx.doi.org/10.1111/j.1365-246X.1997.tb00951.x https://academic.oup.com/gji/article-lookup/doi/10.1111/j.1365-246X.1997.tb00951.x},
  doi = {http://dx.doi.org/10.1111/j.1365-246X.1997.tb00951.x}
}
Hrouda, F., Jelínek, V. & Zapletal, K. (1997), "Refined technique for susceptibility resolution into ferromagnetic and paramagnetic components based on susceptibility temperature-variation measurement"; Geophysical Journal International, Vol. 129 (3) , pp. 715-719, Blackwell Publishing Ltd
Abstract: The measurement of the temperature variation of magnetic susceptibility can be used for the separation of ferromagnetic and paramagnetic susceptibility components. The method suggested by Hrouda (1994) assumes a hyperbolic dependence of paramagnetic, susceptibility and constant ferromagnetic susceptibility in the temperature interval used for the separation. Our new method works with a paramagnetic hyperbola again, but assumes that the ferromagnetic susceptibility temperature variation is represented by a linear relationship in the resolution interval, as indicated by the investigation of monomineralic ferromagnetic fractions.
BibTeX:
@article{GJI:GJI715,
  author = {Hrouda, František and Jelínek, V and Zapletal, Karel},
  title = {Refined technique for susceptibility resolution into ferromagnetic and paramagnetic components based on susceptibility temperature-variation measurement},
  journal = {Geophysical Journal International},
  publisher = {Blackwell Publishing Ltd},
  year = {1997},
  volume = {129},
  number = {3},
  pages = {715--719},
  url = {http://gji.oxfordjournals.org/cgi/doi/10.1111/j.1365-246X.1997.tb04506.x},
  doi = {http://dx.doi.org/10.1111/j.1365-246X.1997.tb04506.x}
}
Hrouda, F., Schulmann, K., Suppes, M. et al. (1997), "Quantitative relationship between low-field AMS and phyllosilicate fabric: a review"; Phys. Chem. Earth, Vol. 22 , pp. 153-156
BibTeX:
@article{Hrouda1997,
  author = {Hrouda, František and Schulmann, Karel and Suppes, M and Ullemayer, K and de Wall, Helga and Weber, K},
  title = {Quantitative relationship between low-field AMS and phyllosilicate fabric: a review},
  journal = {Phys. Chem. Earth},
  year = {1997},
  volume = {22},
  pages = {153--156}
}
Jelínek, V. & Pokorný, J. (1997), "Some new concepts in technology of transformer bridges for measuring susceptibility anisotropy of rocks"; Physics and Chemistry of the Earth, Vol. 22 (1-2) , pp. 179-181
Abstract: The group of Rock Magnetism of Brno has many year experience with using, developing and producing the AC bridges of so called transformer type. After remindering the principle of A.C. bridge and brief historical outline the attention is focused on the type KLY-3S, which has an outstanding sensitivity of about 2.5×10-8 for bulk susceptibility and 1.2×10-8 for anisotropy. The instrument takes advantage of original digital zeroing system and employes the method of spinning specimen. Operating the bridge is extremaly easy. The instrument is also equipped with a furnace, especially for Curie temperatures measurement. Another supplement is available for measuring susceptibility changes in low temperatures down to the liquid nitrogen.
BibTeX:
@article{Jelinek1997,
  author = {Jelínek, V and Pokorný, Jiří},
  title = {Some new concepts in technology of transformer bridges for measuring susceptibility anisotropy of rocks},
  journal = {Physics and Chemistry of the Earth},
  year = {1997},
  volume = {22},
  number = {1-2},
  pages = {179--181},
  url = {http://www.sciencedirect.com/science/article/pii/S0079194697000992},
  doi = {http://dx.doi.org/10.1016/S0079-1946(97)00099-2}
}
Parry, M., Štípská, P., Schulmann, K. et al. (1997), "Tonalite sill emplacement at an oblique plate boundary: northeastern margin of the Bohemian Massif"; Tectonophysics, Vol. 280 (1-2) , pp. 61-81
Abstract: A tonalitic sill has been examined at the Variscan transpressive boundary of the Lugian and Silesian plates at the NE margin of the Bohemian Massif. A structural, petrological and geochronological study reveals that it was emplaced syn-tectonically with major ductile shearing in lower crustal rocks. Magmatic and pre-rheological critical melt percentage (RCMP) fabrics are concordant with the hanging wall structures but discordant with those of the footwall. The AMS study shows the predominance of flattening strain at the margins and plane strain fabrics in the core. Numerical modelling of AMS fabrics is in good agreement with the hypothesis of magma flow and deformation in oblique transpression. A tectonic model was developed explaining emplacement and syn-tectonic deformation of progressively cooled tonalitic intrusion.
BibTeX:
@article{Parry1997,
  author = {Parry, Matthew and Štípská, Pavla and Schulmann, Karel and Hrouda, František and Ježek, Josef and Kröner, Alfred},
  title = {Tonalite sill emplacement at an oblique plate boundary: northeastern margin of the Bohemian Massif},
  journal = {Tectonophysics},
  year = {1997},
  volume = {280},
  number = {1-2},
  pages = {61--81},
  url = {http://linkinghub.elsevier.com/retrieve/pii/S0040195197001467},
  doi = {http://dx.doi.org/10.1016/S0040-1951(97)00146-7}
}
Dearing, J. A., Dann, R. J. L., Hay, K. et al. (1996), "Frequency-dependent susceptibility measurements of environmental materials"; Geophysical Journal International, Vol. 124 (1) , pp. 228-240
BibTeX:
@article{doi:10.1111/j.1365-246X.1996.tb06366.x,
  author = {Dearing, J A and Dann, R J L and Hay, K and Lees, J A and Loveland, P J and Maher, B A and O'Grady, K},
  title = {Frequency-dependent susceptibility measurements of environmental materials},
  journal = {Geophysical Journal International},
  year = {1996},
  volume = {124},
  number = {1},
  pages = {228--240},
  url = {+ http://dx.doi.org/10.1111/j.1365-246X.1996.tb06366.x https://academic.oup.com/gji/article-lookup/doi/10.1111/j.1365-246X.1996.tb06366.x},
  doi = {http://dx.doi.org/10.1111/j.1365-246X.1996.tb06366.x}
}
Hrouda, F. & Henry, B. (1996), "Mathematical modelling of factors affecting the regression line method for separation of ferromagnetic AMS from total rock AMS"; Acta Universitatis Carolinae, Geologica, Vol. 40 (1) , pp. 5-14
Abstract: Our analysis of the relationship between the principal susceptibilities and the mean susceptibility, on which the regression line method for the separation of ferromagnetic and paramagnetic AMS components is based, showed an another possible solution than that shown by Henry (1983) and Henry and Daly (1983). The slopes of the straight lines of the individual elements of the susceptibility tensor versus the mean susceptibility define the normed tensor of the ferromagnetic AMS component only in the case that the variation of the mean susceptibility is solely due to the variation in the content of ferromagnetic minerals. If the variation in rock mean susceptibility is mostly due to the variable content of paramagnetic minerals, the slopes of the above straight lines define the normed tensor of the paramagnetic AMS component.
BibTeX:
@article{Hrouda1996,
  author = {Hrouda, František and Henry, Bernard},
  title = {Mathematical modelling of factors affecting the regression line method for separation of ferromagnetic AMS from total rock AMS},
  journal = {Acta Universitatis Carolinae, Geologica},
  year = {1996},
  volume = {40},
  number = {1},
  pages = {5--14},
  url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-0030419648&partnerID=tZOtx3y1}
}
Hrouda, F., Chlupáčová, M. & Friedrich, D. (1996), "Temperature variations of magnetic susceptibility in rocks of the KTB pilot borehole and its vicinity (German part of the Bohemian Massif) and their geological and geophysical implications"; Journal of the Czech Geological Society, Vol. 41 (3-4) , pp. 176-182
Abstract: The temperature variation of magnetic susceptibility of specimens selected from the KTB pilot borehole (German part of the Bohemian Massif) and sampled in the vicinity of the borehole were investigated by means of the CS-2 Apparatus and KLY-2 Kappabridge. The purpose of this investigation was to identify the minerals that carry the magnetism of the rocks under conside-ration. In weakly magnetic rocks the rock susceptibility is carried mostly by paramagnetic minerals (biotite in gneisses, hornblende in amphibolites) and only subordinately by magnetite. In strongly magnetic specimens the main contributors to the rock susceptibility are pyrrhotite and magnetite.
BibTeX:
@article{Hrouda1996a,
  author = {Hrouda, František and Chlupáčová, Marta and Friedrich, Dietlinde},
  title = {Temperature variations of magnetic susceptibility in rocks of the KTB pilot borehole and its vicinity (German part of the Bohemian Massif) and their geological and geophysical implications},
  journal = {Journal of the Czech Geological Society},
  year = {1996},
  volume = {41},
  number = {3-4},
  pages = {176--182},
  url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-0030390830&partnerID=tZOtx3y1}
}
Hrouda, F. & Henry, B. (1996), "Mathematical modeling of factors affecting the regression line method for separation of ferromagnetic AMS from total rock AMS"; Acta Univ.Carol., Geologica, Vol. 40 , pp. 3-12
BibTeX:
@article{Hrouda1996b,
  author = {Hrouda, František and Henry, Bernard},
  title = {Mathematical modeling of factors affecting the regression line method for separation of ferromagnetic AMS from total rock AMS},
  journal = {Acta Univ.Carol., Geologica},
  year = {1996},
  volume = {40},
  pages = {3--12}
}
Friedrich, D., Hrouda, F. & Chlupáčová, M. (1995), "Relationship between paramagnetic and ferrimagnetic anisotropies in selected specimens of the KTB pilot borehole and its vicinity (German part of the Bohemian massif)"; Sci. Drilling, Vol. 5 , pp. 3-15
Abstract: In rock specimens selected from the KTB pilot borehole (gneiss and amphibolite) and from surface outcrops in the vicinity of the borehole (amphibolite) low-field and high-field magnetic anisotropies were investigated in order to resolve the total AMS into the ferrimagnetic and paramagnetic components. In weakly magnetic rocks, i.e. those with mean susceptibility less than 5 x 10-4, the paramagnetic anisotropy controls the rock anisotropy, while in strongly magnetic rocks the contribution of the ferrimagnetic component is stronger or even dominant. The orientations of the principal directions in both the components are coaxial
BibTeX:
@article{Friedrich1995,
  author = {Friedrich, Dietlinde and Hrouda, František and Chlupáčová, Marta},
  title = {Relationship between paramagnetic and ferrimagnetic anisotropies in selected specimens of the KTB pilot borehole and its vicinity (German part of the Bohemian massif)},
  journal = {Sci. Drilling},
  year = {1995},
  volume = {5},
  pages = {3--15}
}
Hrouda, F. & Přichystal, A. (1995), "Magnetic fabric relationship between Palaeozoic volcanic and sedimentary rocks in the Nizky Jesenik Mts., NE Moravia"; , Vol. 40 (1-2)Journal - Czech Geological Society , pp. 91-102
Abstract: Anisotropy of magnetic susceptibility was used to investigate the fabric of magnetic minerals in Palaeozoic volcanic rocks of the Sternberk-Horni Benesov Belt in the Nizky Jesenik Mts. and in surrounding Lower Carboniferous sedimentary rocks (NE Bohemian Massif). The orientations of the magnetic fabric elements are near those in surrounding sedimentary rocks west of the Sternberk-Horni Benesov Belt. The magnetic fabric in the volcanic rocks investigated is deformational in origin and had at least a part of its deformational history the same as the magnetic fabric of surrounding sedimentary rocks. -from Authors
BibTeX:
@misc{Hrouda1995,
  author = {Hrouda, František and Přichystal, A},
  title = {Magnetic fabric relationship between Palaeozoic volcanic and sedimentary rocks in the Nizky Jesenik Mts., NE Moravia},
  booktitle = {Journal - Czech Geological Society},
  year = {1995},
  volume = {40},
  number = {1-2},
  pages = {91--102},
  url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-0029537274&partnerID=tZOtx3y1}
}
Hrouda, F. (1994), "A technique for the measurement of thermal changes of magnetic susceptibility of weakly magnetic rocks by the CS-2 apparatus and KLY-2 Kappabridge"; Geophysical Journal International, Vol. 118 (3) , pp. 604-612, Blackwell Publishing Ltd
Abstract: Techniques for the correction of the effect of the furnace signal on the data measured in the investigation of thermal changes of magnetic susceptibility of weakly magnetic rocks using the CS-2 apparatus and KLY-2 Kappabridge are described. A new method is developed for separating the ferromagnetic and paramagnetic room temperature susceptibility components even for the case in which new magnetite forms during heating.
BibTeX:
@article{GJI:GJI604,
  author = {Hrouda, František},
  title = {A technique for the measurement of thermal changes of magnetic susceptibility of weakly magnetic rocks by the CS-2 apparatus and KLY-2 Kappabridge},
  journal = {Geophysical Journal International},
  publisher = {Blackwell Publishing Ltd},
  year = {1994},
  volume = {118},
  number = {3},
  pages = {604--612},
  url = {http://dx.doi.org/10.1111/j.1365-246X.1994.tb03987.x http://gji.oxfordjournals.org/cgi/doi/10.1111/j.1365-246X.1994.tb03987.x},
  doi = {http://dx.doi.org/10.1111/j.1365-246X.1994.tb03987.x}
}
Hrouda, F. (1994), "Mathematical modelling of the behaviour of passive fabric elements (and corresponding AMS) in the transpression zone"; , Textures of geological materials , pp. 381-392, Oberusel
BibTeX:
@incollection{Hrouda1994,
  author = {Hrouda, František},
  title = {Mathematical modelling of the behaviour of passive fabric elements (and corresponding AMS) in the transpression zone},
  booktitle = {Textures of geological materials},
  publisher = {Oberusel},
  year = {1994},
  pages = {381--392}
}
Jelínek, V., Hrouda, F. & Tarling, D. (1994), "New parameters for characterization of fabrics of linear and planar elements using orientation tensor"; , Textures of geological materials , pp. 393-399, DGM Verlag Oberursel
BibTeX:
@inbook{Hrouda1994a,
  author = {Jelínek, V and Hrouda, František and Tarling, Donald},
  title = {New parameters for characterization of fabrics of linear and planar elements using orientation tensor},
  booktitle = {Textures of geological materials},
  publisher = {DGM Verlag Oberursel},
  year = {1994},
  pages = {393--399}
}
Hrouda, F., Melka, R. & Schulmann, K. (1994), "Periodical changes in fabric intensity during simple shear deformation and its implications for magnetic susceptibility anisotropy of sedimentary and volcanic rocks"; , Vol. 38 (1)Acta Universitatis Carolinae - Geologica , pp. 37-56
Abstract: Reorientation of initially uniformly distributed rigid grains during pure shear and simple shear deformation has been mathematically modelled. During progressive pure shear deformation the fabric intensity increases, while simple shear deformation produces oscillatory fabric intensitites, fabric symmetry remaining in both cases the same. Modelling of anisotropy of magnetic susceptibility showed similar evolution in pure shear and simple shear regimes. Empiric AMS data from Velky Roudny lava flow and from turbidite sandstones fit well the simple shear model. -from Authors
BibTeX:
@misc{Hrouda1994b,
  author = {Hrouda, František and Melka, Radek and Schulmann, Karel},
  title = {Periodical changes in fabric intensity during simple shear deformation and its implications for magnetic susceptibility anisotropy of sedimentary and volcanic rocks},
  booktitle = {Acta Universitatis Carolinae - Geologica},
  year = {1994},
  volume = {38},
  number = {1},
  pages = {37--56},
  url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-0028682576&partnerID=tZOtx3y1}
}
Hrouda, F. (1993), "Theoretical models of magnetic anisotropy to strain relationship revisited"; Physics of the Earth and Planetary Interiors, Vol. 77 (3-4) , pp. 237-249
Abstract: Mathematical modelling of the relationships between the low-field magnetic anisotropy and strain are redeveloped, and the calculated data are compared with the degree of anisotropy for various rock types. It is found that the degree of anisotropy for realistic strain magnitudes is unrealistically high in the ‘passive' model. The ‘ductile' model, for which the degree of anisotropy depends on the magnetic grain the matrix viscosity ratio, becomes realistic at high viscosity contrasts. In the ‘line/plane' model, the theoretical degree of anisotropy corresponds well to the natural degree of anisotropy for rocks in which the carrier of magnetic anisotropy is either magnetite or phyllosilicate minerals; by contrast, in the case of haematite and pyrrhotite, the modelled degree of anisotropy is much higher than the natural values. In the ‘viscous' model, the calculated degree of anisotropy corresponds well to that measured in sedimentary and volcanic rocks. In the models imposing pure shear strain, the natural logarithm of the degree of anisotropy to natural strain relationship can be approximately represented by a straight line, at least for low to intermediate strains; the proportionality constant varies according to the specific model and the specific carrier of the anisotropy of magnetic susceptibility.
BibTeX:
@article{Hrouda1993,
  author = {Hrouda, František},
  title = {Theoretical models of magnetic anisotropy to strain relationship revisited},
  journal = {Physics of the Earth and Planetary Interiors},
  year = {1993},
  volume = {77},
  number = {3-4},
  pages = {237--249},
  url = {http://www.sciencedirect.com/science/article/pii/003192019390101E http://linkinghub.elsevier.com/retrieve/pii/003192019390101E},
  doi = {http://dx.doi.org/10.1016/0031-9201(93)90101-E}
}
Hrouda, F. & Potfaj, M. (1993), "Deformation of sediments in the post-orogenic Intra-Carpathian Paleogene Basin as indicated by magnetic anisotropy"; Tectonophysics, Vol. 224 (4) , pp. 425-434
Abstract: In sandstones of the Intra-Carpathian Paleogene in central areas of the Inner West Carpathians (the Liptov depression) the magnetic fabric is essentially sedimentary in origin. Towards the margin of the West Carpathians (the Skorus̆inské vrchy Hills) the magnetic fabric indicates an influence of deformation on the sedimentary magnetic fabric. The effect of deformation is very strong at the very margin (the Zázrivá depression). This is interpreted as the effect of closure of the basins of the neighbouring klippen and flysch belts; the post-Paleogene deformation associated with the closing probably propagated into the Inner Carpathians.
BibTeX:
@article{Hrouda1993,
  author = {Hrouda, František and Potfaj, Michal},
  title = {Deformation of sediments in the post-orogenic Intra-Carpathian Paleogene Basin as indicated by magnetic anisotropy},
  journal = {Tectonophysics},
  year = {1993},
  volume = {224},
  number = {4},
  pages = {425--434},
  url = {http://www.sciencedirect.com/science/article/pii/004019519390042I},
  doi = {http://dx.doi.org/10.1016/0040-1951(93)90042-I}
}
Hrouda, F. & Potfaj, M. (1993), "Magnetic anisotropy as an indicator of the weak ductile deformation of the Intracarpathian Palaeogene and the Magura Flysch (in Czech)"; Záp. Karpaty, geol.,, Vol. 17 , pp. 121-134
BibTeX:
@article{Hrouda1993a,
  author = {Hrouda, František and Potfaj, Michal},
  title = {Magnetic anisotropy as an indicator of the weak ductile deformation of the Intracarpathian Palaeogene and the Magura Flysch (in Czech)},
  journal = {Záp. Karpaty, geol.,},
  year = {1993},
  volume = {17},
  pages = {121--134}
}
Hrouda, F. (1993), "Variscan magnetic fabric overprinting in sedimentary and crystalline thrust sheets in the NE Bohemian Massif"; Tectonics, Vol. 12 (2) , pp. 507-518
Abstract: The magnetic fabric of pre-Cambrian and Devonian crystalline rocks of the Hrubý Jeseník Mountains and of Lower Carboniferous sedimentary rocks of the Nízký Jeseník Mountains is predominantly deformational in origin. The orientations of the tectonic magnetic fabric elements are similar in all rocks and geological units investigated. At least one strong deformation phase affected both the sedimentary and crystalline complexes, overprinting the original depositional magnetic fabric in sedimentary rocks as well as earlier deformational magnetic fabrics in crystalline rocks. The overprinted magnetic fabric is probably of Variscan origin.
BibTeX:
@article{Hrouda1993b,
  author = {Hrouda, František},
  title = {Variscan magnetic fabric overprinting in sedimentary and crystalline thrust sheets in the NE Bohemian Massif},
  journal = {Tectonics},
  year = {1993},
  volume = {12},
  number = {2},
  pages = {507--518},
  url = {http://doi.wiley.com/10.1029/92TC01569},
  doi = {http://dx.doi.org/10.1029/92TC01569}
}
Hrouda, F. (1993), "Magnetic fabric relationship between crystalline and Variscan sedimentary complexes in Eastern Bohemian Massif"; , Rhenohercynian and Subvariscan Fold Belts , pp. 227-240, Vieweg and Sohn
BibTeX:
@inbook{Hrouda1993c,
  author = {Hrouda, František},
  title = {Magnetic fabric relationship between crystalline and Variscan sedimentary complexes in Eastern Bohemian Massif},
  booktitle = {Rhenohercynian and Subvariscan Fold Belts},
  publisher = {Vieweg and Sohn},
  year = {1993},
  pages = {227--240}
}
Hrouda, F., Pros, Z. & Wohlgemuth, J. (1993), "Development of magnetic and elastic anisotropies in slates during progressive deformation"; Physics of the Earth and Planetary Interiors, Vol. 77 (3-4) , pp. 251-265
Abstract: Magnetic and elastic anisotropies were investigated in rocks of the Nízký Jeseník Mountains (northeast Bohemian Massif) ranging in lithology from almost unmetamorphosed sediments, through slate, to phyllite, and showing a range of structural styles from sedimentary, through spaced and slaty cleavage, to metamorphic schistosity. In unmetamorphosed and undeformed sedimentary rocks, both the anisotropies display close relationships to the sedimentary fabric. During the development of the spaced and slaty cleavage they are gradually re-oriented into the attitudes of the deformational fabrics, and in the rocks with metamorphic schistosity they are fully related to the deformational fabric elements, which can be oriented in a very different way from the original sedimentary structures. The magnetic anisotropy is mostly due to the preferred orientation of phyllosilicates generated during very weak regional metamorphism, and subordinately due to the preferred orientation of magnetite. The elastic anisotropy is probably controlled by the preferred orientation of phyllosilicates and by the existence of oriented systems of microcracks.
BibTeX:
@article{Hrouda1993d,
  author = {Hrouda, František and Pros, Zdeněk and Wohlgemuth, Jiří},
  title = {Development of magnetic and elastic anisotropies in slates during progressive deformation},
  journal = {Physics of the Earth and Planetary Interiors},
  year = {1993},
  volume = {77},
  number = {3-4},
  pages = {251--265},
  url = {http://www.sciencedirect.com/science/article/pii/003192019390102F},
  doi = {http://dx.doi.org/10.1016/0031-9201(93)90102-F}
}
Jelínek, V. (1993), "Theory and measurement of the anisotropy of isothermal remanent magnetization of rocks"; Travaux Géophysiques, Vol. 37 , pp. 124-134
BibTeX:
@article{Jelinek1993,
  author = {Jelínek, V},
  title = {Theory and measurement of the anisotropy of isothermal remanent magnetization of rocks},
  journal = {Travaux Géophysiques},
  year = {1993},
  volume = {37},
  pages = {124--134},
  url = {http://scholar.google.com/scholar?hl=en&btnG=Search&q=intitle:Theory+and+measurment+of+the+anisotropy+of+isothermal+remanent+magnetization+of+rocks#0}
}
Tarling, D. & Hrouda, F. (1993), "The Magnetic Anisotropy of Rocks"; , , pp. 217, Chapman & Hall
Abstract: This book provides the background, physical instrumentation and geological aspects behind any study of the magnetic anisotropy of a rock in a comprehensive and practical way. After studying this book, readers in the geosciences will be encouraged to use this simple, rapid and inexpensive technique in their studies of rocks.
BibTeX:
@book{Tarling1993,
  author = {Tarling, Donald and Hrouda, František},
  title = {The Magnetic Anisotropy of Rocks},
  publisher = {Chapman & Hall},
  year = {1993},
  pages = {217},
  url = {http://www.springer.com/it/book/9780412498800}
}
Zapletal, K. (1993), "Effect of intergrowths of the ferrimagnetic and antiferromagnetic phases on the rock magnetic properties of natural pyrrhotites"; Physics of the Earth and Planetary Interiors, Vol. 76 (1-2) , pp. 151-162
Abstract: Several types of massive natural pyrrhotites were characterized using low-field magnetic susceptibility and its anisotropy (AMS), thermomagnetic analysis and the colloid method. The pyrrhotites studied differed in the concentration of the ferrimagnetic (Fe7S8) phase (ranging from 100 to 5%), this phase being microscopically intergrown with the antiferromagnetic (Fe9S10) phase. An artificial specimen containing powdered pyrrhotite dispersed in a diamagnetic material was prepared from each pyrrhotite type; hysteresis curves of isothermal remanent magnetization (IRM) and AMS were measured on these specimens. The IRM induced in a 1 T field and the mean bulk susceptibility (k) of dispersed pyrrhotite specimens decrease with decreasing ferrimagnetic phase concentration in the pyrrhotites studied as follows: (1) the IRM (1 T) values range from 30.8 to 1.4 kA m−1; (2) the k values range from 217 × 10−3 to 7.1 × 10−3. During magnetization, AMS was induced in dispersed pyrrhotite specimens (which were nearly isotropic in their original state).
BibTeX:
@article{Zapletal1993,
  author = {Zapletal, Karel},
  title = {Effect of intergrowths of the ferrimagnetic and antiferromagnetic phases on the rock magnetic properties of natural pyrrhotites},
  journal = {Physics of the Earth and Planetary Interiors},
  year = {1993},
  volume = {76},
  number = {1-2},
  pages = {151--162},
  url = {http://www.sciencedirect.com/science/article/pii/003192019390064G},
  doi = {http://dx.doi.org/10.1016/0031-9201(93)90064-G}
}
Herrero-Bervera, E., Walker, G. P. L. & Hrouda, F. (1992), "Application of paleomagnetism to investigate inclined sheet/conesheet emplacement mechanisms [abs.]"; , Vol. v. 2 Abstracts, 3 v. , pp. p. 494
Abstract: Inclined sheet/conesheet complexes that occur in the core region of many major basaltic volcanoes typically consist of thousands of mafic igneous intrusions. Individually, they are small, but collectively, the intrusions have a large volume and comprise a significant proportion of the whole volcanic system. The sheeted complexes that are their representatives in ophiolites and are generated in oceanic spreading ridges, are thought to constitute one layer in a typical oceanic crust. Despite their evident importance in basaltic volcanic systems, conesheet complexes are still poorly understood, and their origin is the subject of several competing hypotheses. We have applied paleomagnetic techniques to test these hypotheses in one study area: the intrusions on the island of Kauai, in Hawaii. We have studied not only the intrusive sheet, but also the lava flows that were sampled in cross sections passing from the underlying lava flow through the intrusive sheet to the overlying lava flow. The results from the Anisotropic Magnetic Susceptibility (AMS) measurements have indicated that the degree of the AMS is very low in lava flows (mostly less than 11 of the total anisotropy), and in the intrusive sheets, the AMS is higher in average but more variable. The values of the shape parameters (T) have indicated relatively variable shapes of the susceptibility ellipsoids, both in the lava and in the intrusive sheets. However, on average, the magnetic fabric is planar in lava flows and linear in intrusive sheets. This confirms different emplacement regimes in lava flows and intrusive sheets, as indicated by the degree of AMS. Whereas the planar magnetic fabric in lava flows logically reflects the movement of lava as large sheets, the penetration of intrusive sheet boundaries are fixed and the magma can only move in tunnels between them. This way of emplacement is in contradiction with that of dikes in which the magnetic fabric is mostly planar. Nevertheless, the mechanism of emplacement of intrusive sheets is not known very well and needs further detailed studies in which the AMS can play an important role.
BibTeX:
@misc{Herrero-Bervera1992,
  author = {Herrero-Bervera, Emilio and Walker, George P L and Hrouda, František},
  title = {Application of paleomagnetism to investigate inclined sheet/conesheet emplacement mechanisms [abs.]},
  booktitle = {Abstracts, 3 v.},
  year = {1992},
  volume = {v. 2},
  pages = {p. 494}
}
Hrouda, F. (1992), "Separation of a component of tectonic deformation from a complex magnetic fabric"; Journal of Structural Geology, Vol. 14 (1) , pp. 65-71
Abstract: A method has been developed for separation of the deformational component from a complex rock fabric. For the separation, data on the final (measured) fabric and the primary (pre-deformational) fabric are necessary as input. The primary fabric data are obtained either from measurements in terrains where gradual transitions from primary to deformational fabrics occur or, in the case of magnetic anisotropy, this may be obtained from data in the literature on individual rock types. Examples of the use of the method are presented for rocks from the Nízký Jeseník Mountains of the NE Bohemian massif.
BibTeX:
@article{Hrouda1992,
  author = {Hrouda, František},
  title = {Separation of a component of tectonic deformation from a complex magnetic fabric},
  journal = {Journal of Structural Geology},
  year = {1992},
  volume = {14},
  number = {1},
  pages = {65--71},
  url = {http://www.sciencedirect.com/science/article/pii/019181419290145M},
  doi = {http://dx.doi.org/10.1016/0191-8141(92)90145-M}
}
Melka, R., Schulmann, K., Schulmannova, B. et al. (1992), "The evolution of perpendicular linear fabrics in synkinematically emplaced tourmaline granite (central moravia-bohemian massif)"; Journal of Structural Geology, Vol. 14 (5) , pp. 605-620
Abstract: Sheets of leucocratic peraluminous tourmaline granite were synkinematically emplaced into metasediments of the Svratka Crystalline Unit during the Variscan orogeny. The granite was deformed under hightemperature conditions close to the solidus, as indicated by quartz microstructures and the presence of prism (c) glide in quartz. Decrease in the temperature of deformation causing orthogneissification of the granite is documented by transition from prism (c) to prism (a) and basal (a) glide operating in quartz grains. Two mutually perpendicular stretching lineations originated during high-temperature deformation of the granite. Detailed three-dimensional analysis of tourmaline preferred orientations underlining both lineations has been performed and the distributions have been compared with theoretical predictions of Jeffery and March for rotation of rigid linear markers. The origin of mutually perpendicular linear fabrics is discussed on the basis of numerical models. Transpression, considered as a combination of northwestward shearing accompanied by shortening across and lengthening along the shear plane, is proposed to explain the perpendicular linear fabrics observed. ?? 1992.
BibTeX:
@article{Melka1992,
  author = {Melka, Radek and Schulmann, Karel and Schulmannova, Barbora and Hrouda, František and Lobkowicz, Michal},
  title = {The evolution of perpendicular linear fabrics in synkinematically emplaced tourmaline granite (central moravia-bohemian massif)},
  journal = {Journal of Structural Geology},
  year = {1992},
  volume = {14},
  number = {5},
  pages = {605--620},
  doi = {http://dx.doi.org/10.1016/0191-8141(92)90160-X}
}
Zapletal, K. (1992), "Self-reversal of isothermal remanent magnetization in a pyrrhotite (Fe7S8) crystal"; Physics of the Earth and Planetary Interiors, Vol. 70 (3-4) , pp. 302-311
Abstract: The remanent magnetization induced at room temperature (IRM) was measured for powder and massive specimens separated from a Fe7S8 crystal. To characterize the crystal, several methods were used including Mössbauer spectroscopy, thermomagnetic analysis, low-field susceptibility anisotropy and magnetic colloid method. Self-reversals of IRM were revealed in the massive crystal fragment after its magnetization in magnetic fields of the order of 10–102 mT. Both normal and reverse IRM vectors lay in the maximum susceptibility plane perpendicular to the crystallographic c′-axis of the crystal. A twinning also perpendicular to the crystal's c′-axis and a very low coercivity in each twin (monocrystallic layer) probably support the origin of the reverse IRM in the crystal.
BibTeX:
@article{Zapletal1992,
  author = {Zapletal, Karel},
  title = {Self-reversal of isothermal remanent magnetization in a pyrrhotite (Fe7S8) crystal},
  journal = {Physics of the Earth and Planetary Interiors},
  year = {1992},
  volume = {70},
  number = {3-4},
  pages = {302--311},
  url = {http://www.sciencedirect.com/science/article/pii/0031920192901963},
  doi = {http://dx.doi.org/10.1016/0031-9201(92)90196-3}
}
Hrouda, F. (1991), "Models of magnetic anisotropy variations in sedimentary thrust sheets"; Tectonophysics, Vol. 185 (3-4) , pp. 203-210
Abstract: Magnetic anisotropy variation in sedimentary thrust sheets was modelled through the extension of strain models in thrust sheets (Coward and Kim, 1981; Sanderson, 1982), using the empirical relationship between the magnetic anisotropy and strain and respecting the pre-deformational anisotropy of sedimentary rocks. In thrust sheets deformed by simple shear and lateral lengthening the magnetic foliations remain near the bedding, while in thrust sheets deformed by simple shear and lateral shortening the magnetic foliation may deviate strongly from the bedding, even creating a girdle pattern in its poles.
BibTeX:
@article{Hrouda1991,
  author = {Hrouda, FrantiŠek},
  title = {Models of magnetic anisotropy variations in sedimentary thrust sheets},
  journal = {Tectonophysics},
  year = {1991},
  volume = {185},
  number = {3-4},
  pages = {203--210},
  url = {http://www.sciencedirect.com/science/article/pii/004019519190444W},
  doi = {http://dx.doi.org/10.1016/0040-1951(91)90444-W}
}
Hrouda, F. & Kahan, Š. (1991), "The magnetic fabric relationship between sedimentary and basement nappes in the High Tatra Mountains, N. Slovakia"; Journal of Structural Geology, Vol. 13 (4) , pp. 431-442
Abstract: In the High Tatra Mountains (N. Slovakia), the magnetic fabrics are deformational in origin in sedimentary rocks of the Krížna nappe, in sedimentary rocks covering the underlying crystalline complex, and in granitoids and metamorphic rocks of this complex. The patterns of the principal susceptibilities are similar in all these units; their most important feature is a girdle in magnetic foliation poles oriented NNW-SSE to N-S. In sedimentary formations the magnetic fabric pattern is compatible with that predicted by mathematical modelling to develop during a complex deformation comprising lateral shortening and simple shear, which is characteristic of nappe deformation. Consequently, the magnetic fabric in the High Tatra Mountains probably resulted from deformation associated with the formation and movement of the nappes, during which not only the sedimentary strata, but also the crystalline complex, were thrust over the North European platform.
BibTeX:
@article{Hrouda1991a,
  author = {Hrouda, František and Kahan, Štefan},
  title = {The magnetic fabric relationship between sedimentary and basement nappes in the High Tatra Mountains, N. Slovakia},
  journal = {Journal of Structural Geology},
  year = {1991},
  volume = {13},
  number = {4},
  pages = {431--442},
  url = {http://adsabs.harvard.edu/abs/1991JSG....13..431H http://linkinghub.elsevier.com/retrieve/pii/019181419190016C},
  doi = {http://dx.doi.org/10.1016/0191-8141(91)90016-C}
}
Hrouda, F. & Schulmann, K. (1990), "Conversion of the magnetic susceptibility tensor into the orientation tensor in some rocks"; Physics of the Earth and Planetary Interiors, Vol. 63 (1-2) , pp. 71-77
Abstract: The preferred orientation of minerals in a rock with a structural or sedimentary fabric can be referred to by the orientation tensor. This paper describes the determination of the orientation tensor of the crystallographic c′-axes from the rock magnetic anisotropy and the mineral anisotropy degree, in rocks in which the magnetic anisotropy is dominantly carried by one mineral with uniaxial magnetic anisotropy (e.g. phyllosilicates, pyrrhotite, hematite). The orientation tensor of biotite c′-axes in four samples of the Bíteš orthogneiss determined in this way is similar to that determined independently through the universal stage measurement of biotite leaves in thin sections and is obtained much more rapidly by the magnetic method.
BibTeX:
@article{Hrouda1990,
  author = {Hrouda, František and Schulmann, Karel},
  title = {Conversion of the magnetic susceptibility tensor into the orientation tensor in some rocks},
  journal = {Physics of the Earth and Planetary Interiors},
  year = {1990},
  volume = {63},
  number = {1-2},
  pages = {71--77},
  url = {http://www.sciencedirect.com/science/article/pii/0031920190900612},
  doi = {http://dx.doi.org/10.1016/0031-9201(90)90061-2}
}
Hrouda, F. & Hanák, J. (1990), "Magnetic fabric of sedimentary formations of the Strazovske vrchy Mts., sedimentological and tectonic implications"; Sbor. geol. Věd,, Vol. 24 , pp. 91-105
BibTeX:
@article{Hrouda1990,
  author = {Hrouda, František and Hanák, Jaromír},
  title = {Magnetic fabric of sedimentary formations of the Strazovske vrchy Mts., sedimentological and tectonic implications},
  journal = {Sbor. geol. Věd,},
  year = {1990},
  volume = {24},
  pages = {91--105}
}
Hrouda, F. & Jelínek, V. (1990), "Resolution of ferrimagnetic and paramagnetic anisotropies in rocks, using combined low-field and high-field measurements"; Geophysical Journal International, Vol. 103 (1) , pp. 75-84
Abstract: A method of separation of ferrimagnetic and paramagnetic components of magnetic anisotropy from the total anisotropy is developed. From the anisotropy measurement of a specimen in a low field (susceptibility anisotropy) and from measurement in two high fields stronger than the saturation field of the ferrimagnetic fraction present, the following anisotropy components can be calculated: susceptibility anisotropy (field-independent) of the paramagnetic fraction, low-field (susceptibility) anisotropy of the ferrimagnetic fraction and high-field anisotropy of the ferrimagnetic fraction. Errors possibly arising from imperfect saturation of the ferrimagnetic fraction in the field practically available are analysed.
BibTeX:
@article{Hrouda1990b,
  author = {Hrouda, František and Jelínek, V},
  title = {Resolution of ferrimagnetic and paramagnetic anisotropies in rocks, using combined low-field and high-field measurements},
  journal = {Geophysical Journal International},
  year = {1990},
  volume = {103},
  number = {1},
  pages = {75--84},
  url = {https://academic.oup.com/gji/article-lookup/doi/10.1111/j.1365-246X.1990.tb01753.x},
  doi = {http://dx.doi.org/10.1111/j.1365-246X.1990.tb01753.x}
}
Hrouda, F. & Hrušková, L. (1990), "On the detection of weak strain parallel to the bedding by magnetic anisotropy: A mathematical model study"; Studia Geophysica et Geodætica, Vol. 34 (4) , pp. 327-341
Abstract: Five mathematical models of the superposition of deformational magnetic fabric on sedimentary magnetic fabric are presented. These models are represented by various combinations of pure shear and simple shear. The diagrams of the variations in the main magnetic anisotropy parameters with strain can help in recognizing weak ductile deformation in sedimentary rocks.
BibTeX:
@article{ref1,
  author = {Hrouda, František and Hrušková, Lenka},
  title = {On the detection of weak strain parallel to the bedding by magnetic anisotropy: A mathematical model study},
  journal = {Studia Geophysica et Geodætica},
  year = {1990},
  volume = {34},
  number = {4},
  pages = {327--341},
  url = {http://link.springer.com/10.1007/BF02316953},
  doi = {http://dx.doi.org/10.1007/BF02316953}
}
Zapletal, K. (1990), "Low-field susceptibility anisotropy of some biotite crystals"; Physics of the Earth and Planetary Interiors, Vol. 63 (1-2) , pp. 85-97
Abstract: The low-field magnetic susceptibility anisotropy (LMA) of weakly magnetic rocks is dominated by paramagnetic minerals among which micas, and mainly biotite, is important. For this reason, the LMA of biotite crystals was investigated in detail. Natural biotite crystals (from ten localities) having a wide range of iron concentration were also studied by other methods, including optical microscopy, X-ray microanalysis, Mössbauer spectroscopy and induced isothermal remanent magnetization. Ferromagnetic inclusions disturbing the magnetic properties of biotite were revealed in some crystals. The measured mean bulk susceptibility of pure crystals (four localities) ranges from 1.0 × 10−3 to 1.8 × 10−3 SI and agrees with the susceptibility calculated from the iron concentration (ranging from 12 to 20 wt.%) determined for each specimen. The susceptibility ellipsoid of pure biotite crystals is rotational about the minimum susceptibility direction parallel to the crystallographic c′-axis, and the anisotropy degree ranges from 1.34 to 1.36.
BibTeX:
@article{Zapletal1990,
  author = {Zapletal, Karel},
  title = {Low-field susceptibility anisotropy of some biotite crystals},
  journal = {Physics of the Earth and Planetary Interiors},
  year = {1990},
  volume = {63},
  number = {1-2},
  pages = {85--97},
  url = {http://www.sciencedirect.com/science/article/pii/0031920190900634},
  doi = {http://dx.doi.org/10.1016/0031-9201(90)90063-4}
}
Henry, B. & Hrouda, F. (1989), "Analyse de la deformation finie des roches par determination de leur anisotropie de susceptibilite magnetique"; , Vol. 308 (8)Comptes Rendus - Academie des Sciences, Serie II , pp. 731-737
Abstract: Application of the March-Fernandez model of deformation to magnetic susceptibility anisotropy of a mineral allows establishing a quantitative relation between magnetic fabric and finite strain. It is then possible to analyze finite strain from magnetic data. This method can be applied to numerous rocks where a single mineral has a strongly dominant effect on the anisotropy of the diaparamagnetic matrix. There is an abridged English version. -English summary
BibTeX:
@misc{Henry1989,
  author = {Henry, Bernard and Hrouda, František},
  title = {Analyse de la deformation finie des roches par determination de leur anisotropie de susceptibilite magnetique},
  booktitle = {Comptes Rendus - Academie des Sciences, Serie II},
  year = {1989},
  volume = {308},
  number = {8},
  pages = {731--737},
  url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-0024486551&partnerID=tZOtx3y1}
}
Hrouda, F. & Lanza, R. (1989), "Magnetic fabric in the Biella and Traversella stocks (Periadriatic Line) : implications for the mode of emplacement"; Physics of the Earth and Planetary Interiors, Vol. 56 (3-4) , pp. 337-348
Abstract: The Biella and Traversella stocks, forming part of the intrusions along the Periadriatic Line, intruded into the Sesia-Lanzo Zone (Italian western Alps) ∼ 30 Ma ago. Samples were collected from 12 localities in the Traversella massif (diorites) and 22 in the Biella massif (granites, syenites, monzonites). In most localities, the fabric is primarily planar, with a distinct foliation of intermediate to subvertical dip. The magnetic lineation is less developed. Its plunge is very variable, marking a girdle pattern. The mean foliations and lineations per locality are scattered. This is probably due to the fact that the outcropping parts of the two stocks are summital, i.e. nearer the roof, and hence the magma movements may have been less regular. In the structurally deepest part of the Biella massif, the magnetic foliation dips regularly to the northwest. Its direction could reflect the pattern of the deep fractures along which the magma rose. The classic models of Owens, to describe the process of magnetic mineral orientation, do not apply to the features of these two stocks. A new model has been constructed to take account of the differences in viscosity contrast between the magnetic mineral crystals and the matrix. Referred to as the ductile model, it offers a suitable representation of the typical situation of crystal mushes and is the most appropriate for the Biella and Traversella stocks.
BibTeX:
@article{Hrouda1989,
  author = {Hrouda, František and Lanza, Roberto},
  title = {Magnetic fabric in the Biella and Traversella stocks (Periadriatic Line) : implications for the mode of emplacement},
  journal = {Physics of the Earth and Planetary Interiors},
  year = {1989},
  volume = {56},
  number = {3-4},
  pages = {337--348},
  url = {http://www.sciencedirect.com/science/article/pii/0031920189901684},
  doi = {http://dx.doi.org/10.1016/0031-9201(89)90168-4}
}
Ellwood, B. B., Chrzanowski, T. H., Hrouda, F. et al. (1988), "Siderite formation in anoxic deep-sea sediments: A synergetic bacteria controlled process with improtant implications in paleomagnetism"; Geology, Vol. 16 (11) , pp. 980-982
Abstract: Recent work on magnetic properties of limestones has demonstrated that the mineral siderite can be very important in paleomagnetism, for two reasons. First, oxidation of siderite produces secondary (daughter) magnetic minerals (magnetite, maghemite, and hematite), either before, during, or after sampling. These daughter products can completely change the magnetic properties of limestone samples and if unrecognized may be one of the primary reasons why many paleomagnetic studies of limestones, especially Paleozoic limestones, are unsuccessful. Second, siderite in weakly magnetized rocks may indicate the potential for successful paleomagnetic results. Because the presence of siderite indicates that the primary magnetic carriers are still intact, appropriate demagnetization methods should yield successful results. We conclude that microenvironmental conditions in anoxic marine sediments may permit the formation of siderite from iron (II) produced during bacterial dissimilatory iron reduction.
BibTeX:
@article{Ellwood1988,
  author = {Ellwood, Brooks B and Chrzanowski, Thomas H and Hrouda, František and Long, Gary J and Buhl, Margaret L},
  title = {Siderite formation in anoxic deep-sea sediments: A synergetic bacteria controlled process with improtant implications in paleomagnetism},
  journal = {Geology},
  year = {1988},
  volume = {16},
  number = {11},
  pages = {980--982},
  url = {http://geology.gsapubs.org/content/16/11/980.abstract},
  doi = {http://dx.doi.org/10.1130/0091-7613(1988)016}
}
Ellwood, B. B., Hrouda, F. & Wagner, J.-J. (1988), "Symposia on magnetic fabrics: introductory comments"; Physics of the Earth and Planetary Interiors, Vol. 51 (4) , pp. 249-252
BibTeX:
@article{Ellwood1988a,
  author = {Ellwood, Brooks B and Hrouda, František and Wagner, Jean-Jacques},
  title = {Symposia on magnetic fabrics: introductory comments},
  journal = {Physics of the Earth and Planetary Interiors},
  year = {1988},
  volume = {51},
  number = {4},
  pages = {249--252},
  url = {http://linkinghub.elsevier.com/retrieve/pii/0031920188900660},
  doi = {http://dx.doi.org/10.1016/0031-9201(88)90066-0}
}
Hrouda, F., Jacko, S. & Hanák, J. (1988), "Parallel magnetic fabrics in metamorphic, granitoid and sedimentary rocks of the Branisko and Čierna hora Mountains (E Slovakia) and their tectonometamorphic control"; Physics of the Earth and Planetary Interiors, Vol. 51 (4) , pp. 271-289
Abstract: The magnetic anisotropy of rocks from the Branisko and Čierna hora Mountains (West Carpathians) was investigated, and the ferromagnetic and paramagnetic components were separated and found to be roughly coaxial. The magnetic fabrics in metamorphic, granitoid, and sedimentary rocks display very similar patterns of principal susceptibilities. Metamorphites underwent a polyphase prograde and retrograde metamorphis, granitoids were metamorphosed retrogressively, and sedimentary rocks suffered a very weak prograde metamorphism. Retrogressive and progressive Alpine metamorphism and the formation of magnetic anisotropy took place simultaneously, before, during. and after the emplacement of the Central West Carpathian nappes.
BibTeX:
@article{Hrouda1988,
  author = {Hrouda, František and Jacko, Stanislav and Hanák, Jaromír},
  title = {Parallel magnetic fabrics in metamorphic, granitoid and sedimentary rocks of the Branisko and Čierna hora Mountains (E Slovakia) and their tectonometamorphic control},
  journal = {Physics of the Earth and Planetary Interiors},
  year = {1988},
  volume = {51},
  number = {4},
  pages = {271--289},
  url = {http://www.sciencedirect.com/science/article/pii/0031920188900696},
  doi = {http://dx.doi.org/10.1016/0031-9201(88)90069-6}
}
Hrouda, F. & Chlupáčová, M. (1988), "Magnetic susceptibility of granites and its petrological significance"; , Výzkum hlubinné stavby Československa, GFÚ SAV Bratislava a Geofyzika Brno , pp. 269-278
BibTeX:
@inproceedings{Hrouda1988a,
  author = {Hrouda, František and Chlupáčová, Marta},
  title = {Magnetic susceptibility of granites and its petrological significance},
  booktitle = {Výzkum hlubinné stavby Československa, GFÚ SAV Bratislava a Geofyzika Brno},
  year = {1988},
  pages = {269--278}
}
Jelínek, V. (1988), "Potential energy density tensor and magnetic anisotropy problems"; Physics of the Earth and Planetary Interiors, Vol. 51 (4) , pp. 361-364
Abstract: The potential energy density tensor describes the potential energy density (or its defined portion) of a rock sample in a homogeneous magnetic field. It is used especially in torque magnetometer measurements to characterize magnetic anisotropy of rocks with various magnetic properties in different magnetic fields. A way to compute this tensor approximately, from a triad of torque curves, is shown.
BibTeX:
@article{Jelinek1988,
  author = {Jelínek, V},
  title = {Potential energy density tensor and magnetic anisotropy problems},
  journal = {Physics of the Earth and Planetary Interiors},
  year = {1988},
  volume = {51},
  number = {4},
  pages = {361--364},
  url = {http://www.sciencedirect.com/science/article/pii/0031920188900775},
  doi = {http://dx.doi.org/10.1016/0031-9201(88)90077-5}
}
Parma, J. (1988), "An automated torque meter for rapid measurement of high-field magnetic anisotropy of rocks"; Physics of the Earth and Planetary Interiors, Vol. 51 (4) , pp. 387-389
Abstract: For the purpose of routine separation of the paramagnetic and ferromagnetic components of magnetic anisotropy, a torque meter has been developed using a special jewel bearing instead of fibre suspension. This solution gives rise to high rapidity and a high degree of automation of measurement. The sensitivity is retained at a reasonable level; the minimum measurable torque is 5 × 10−8N m. The measurement about one axis is fully automated.
BibTeX:
@article{Parma1988,
  author = {Parma, Jan},
  title = {An automated torque meter for rapid measurement of high-field magnetic anisotropy of rocks},
  journal = {Physics of the Earth and Planetary Interiors},
  year = {1988},
  volume = {51},
  number = {4},
  pages = {387--389},
  url = {http://www.sciencedirect.com/science/article/pii/0031920188900805},
  doi = {http://dx.doi.org/10.1016/0031-9201(88)90080-5}
}
Rochette, P. & Hrouda, F. (1988), "Mathematical model relationship between the paramagnetic anisotropy and strain in slates. Discussion. Reply"; Tectonophysics A, Vol. 156 , pp. 313-315
BibTeX:
@article{Rochette1988,
  author = {Rochette, Pierre and Hrouda, František},
  title = {Mathematical model relationship between the paramagnetic anisotropy and strain in slates. Discussion. Reply},
  journal = {Tectonophysics A},
  year = {1988},
  volume = {156},
  pages = {313--315}
}
Hrouda, F. (1987), "Mathematical model relationship between the paramagnetic anisotropy and strain in slates"; Tectonophysics, Vol. 142 (2-4) , pp. 323-327
Abstract: A simple mathematical model is used to investigate the relationship between the paramagnetic anisotropy and strain in slates. The relationship found is similar to the relationship of whole-rock magnetic anisotropy to strain. In weakly magnetic slates, the anisotropy is probably mostly due to paramagnetic phyllosilicates and the whole-rock relationship reflects the paramagnetic fraction.
BibTeX:
@article{Hrouda1987,
  author = {Hrouda, FrantiŠek},
  title = {Mathematical model relationship between the paramagnetic anisotropy and strain in slates},
  journal = {Tectonophysics},
  year = {1987},
  volume = {142},
  number = {2-4},
  pages = {323--327},
  url = {http://www.sciencedirect.com/science/article/pii/0040195187901314},
  doi = {http://dx.doi.org/10.1016/0040-1951(87)90131-4}
}
Gregerová, M., Staněk, J., Hrouda, F. et al. (1986), "Dyke rocks (in Czech)"; , Brněnský masív , pp. 141-166, UJEP Brno
BibTeX:
@incollection{Gregerova1986,
  author = {Gregerová, M and Staněk, J and Hrouda, František and Janák, František and Ondra, P},
  title = {Dyke rocks (in Czech)},
  booktitle = {Brněnský masív},
  publisher = {UJEP Brno},
  year = {1986},
  pages = {141--166}
}
Gregerová, M., Štelcl, J. J., Hájek, J. et al. (1986), "Metabasite Zone (in Czech)"; , Brněnský masív , pp. 87-140, UJEP Brno
BibTeX:
@incollection{Gregerova1986a,
  author = {Gregerová, M and Štelcl, J. Jr and Hájek, J and Hrouda, František and Janák, František and Ondra, P},
  title = {Metabasite Zone (in Czech)},
  booktitle = {Brněnský masív},
  publisher = {UJEP Brno},
  year = {1986},
  pages = {87--140}
}
Hrouda, F. (1986), "The magnetic fabric of sedimentary rocks of the Male Karpaty Mts. and its tectonic implications."; Sbor. geol. Věd,, Vol. 20 , pp. 165-167
BibTeX:
@article{Hrouda1986,
  author = {Hrouda, František},
  title = {The magnetic fabric of sedimentary rocks of the Male Karpaty Mts. and its tectonic implications.},
  journal = {Sbor. geol. Věd,},
  year = {1986},
  volume = {20},
  pages = {165--167}
}
Hrouda, F. & Kapička, A. (1986), "The effect of quartz on the magnetic anisotropy of quartzite"; Studia Geophysica et Geodaetica, Vol. 30 (1) , pp. 39-45
Abstract: The magnetic susceptibility of quartz single crystals is diamagnetic (−14texttimes10 −6 in SI units) and exhibits only very small anisotropy (mostly less than 1%); thus the susceptibility of the quartz matrix in quartzite can be regarded as virtually isotropic. Owing to the influence of the negative and isotropic susceptibility of the quartz matrix, the degree of anisotropy of quartzite, as inferred from model calculations, is higher than that of the ferrimagnetic fraction. This influence is very strong if the mean susceptibility of quartzite is in the vicinity of zero.
BibTeX:
@article{ref1,
  author = {Hrouda, František and Kapička, Aleš},
  title = {The effect of quartz on the magnetic anisotropy of quartzite},
  journal = {Studia Geophysica et Geodaetica},
  year = {1986},
  volume = {30},
  number = {1},
  pages = {39--45},
  url = {http://link.springer.com/10.1007/BF01630853},
  doi = {http://dx.doi.org/10.1007/BF01630853}
}
Štelcl, J., Musilová, L., Štelcl, J. J. et al. (1986), "Crystalline mantle of the Brno Massif (in Czech)"; , Brněnský masív , pp. 167-189, UJEP Brno
BibTeX:
@incollection{Stelcl1986,
  author = {Štelcl, J and Musilová, L and Štelcl, J. Jr and Hájek, J and Hrouda, František and Janák, František and Ondra, P},
  title = {Crystalline mantle of the Brno Massif (in Czech)},
  booktitle = {Brněnský masív},
  publisher = {UJEP Brno},
  year = {1986},
  pages = {167--189}
}
Štelcl, J., Gregerová, M., Štelcl, J. J. et al. (1986), "Granitoids of the Brno massif (in Czech)"; , Brněnský masív , pp. 30-86, UJEP Brno
BibTeX:
@incollection{Stelcl1986a,
  author = {Štelcl, J and Gregerová, M and Štelcl, J. Jr and Hájek, J and Hrouda, František and Janák, František and Ondra, P},
  title = {Granitoids of the Brno massif (in Czech)},
  booktitle = {Brněnský masív},
  publisher = {UJEP Brno},
  year = {1986},
  pages = {30--86}
}
Hrouda, F. (1985), "The magnetic fabric in the Brno massif"; Sbor. geol. Věd, řada UG, Vol. 19 , pp. 89-112
BibTeX:
@article{Hrouda1985,
  author = {Hrouda, František},
  title = {The magnetic fabric in the Brno massif},
  journal = {Sbor. geol. Věd, řada UG},
  year = {1985},
  volume = {19},
  pages = {89--112}
}
Hrouda, F. & Stráník, Z. (1985), "The magnetic fabric of the Ždánice thrust sheet of the flysch belt of the west Carpathians: Sedimentological and tectonic implications"; Sedimentary Geology, Vol. 45 (1-2) , pp. 125-145
Abstract: The magnetic fabric of sandstone of the Ždánice-Hustopeče Formation (Flysch Belt of the West Carpathians) is essentially sedimentary in origin, although affected very weakly by ductile deformation. The magnetic lineation is mostly parallel to the flow direction. The sandstone was probably deposited from thin suspension and the rotation of grains in flowing water was the dominating orientation mechanism. Two systems of currents are indicated, one supplying the basin with clastic material from the source, the second transporting it along the trough. The weak deformation was lengthening parallel to bedding and was due to the strain associated with the horizontal movement of the Ždánice thrust sheet.
BibTeX:
@article{Hrouda1985a,
  author = {Hrouda, František and Stráník, Zdeněk},
  title = {The magnetic fabric of the Ždánice thrust sheet of the flysch belt of the west Carpathians: Sedimentological and tectonic implications},
  journal = {Sedimentary Geology},
  year = {1985},
  volume = {45},
  number = {1-2},
  pages = {125--145},
  url = {http://www.sciencedirect.com/science/article/pii/0037073885900272},
  doi = {http://dx.doi.org/10.1016/0037-0738(85)90027-2}
}
Hrouda, F., Siemes, H., Herres, N. et al. (1985), "The relationship between the magnetic anisotropy and the c-axis fabric in a massive hematite ore."; , Vol. 56 (3)Journal of Geophysics - Zeitschrift fur Geophysik , pp. 174-182
Abstract: Preferred orientation of hematite ore from Minas Gerais, Brazil, was investigated by reflected-light microscopy, X-ray structural goniometry and magnetic anisotropy. A close relationship was found between c-axis fabrics determined by magnetic and non-magnetic methods; experiments confirmed the results of the theoretical treatment. For routine work it is advantageous to use both types of methods, profiting from rapidity of measurement of magnetic anisotropy and from detailed c-axis pole figures of pilot specimens provided by X-ray goniometry. (Authors' abstract)-R.A.H.
BibTeX:
@misc{Hrouda1985b,
  author = {Hrouda, František and Siemes, Heinrich and Herres, N and Hennig-Michaeli, C},
  title = {The relationship between the magnetic anisotropy and the c-axis fabric in a massive hematite ore.},
  booktitle = {Journal of Geophysics - Zeitschrift fur Geophysik},
  year = {1985},
  volume = {56},
  number = {3},
  pages = {174--182},
  url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-0022266728&partnerID=tZOtx3y1}
}
Jelínek, V. (1985), "The physical principles of measuring magnetic anisotropy with the torque magnetometer"; Travaux Geophys., Vol. 33 , pp. 177-198
BibTeX:
@article{Jelinek1985,
  author = {Jelínek, V},
  title = {The physical principles of measuring magnetic anisotropy with the torque magnetometer},
  journal = {Travaux Geophys.},
  year = {1985},
  volume = {33},
  pages = {177--198}
}
Zapletal, K. & Kropáček, V. (1985), "Magnetic anisotropy of polycrystalline haematite induced by A D. C. magnetic field"; Studia Geophysica & Geodaetica, Vol. 29 (4) , pp. 351-361
Abstract: The changes in the anisotropy of initial susceptibility of haematite ores, induced by a D.C. magnetic field are studied. After applying stronger magnetic fields, the changes in the anisotropy parameters are considerable and depend on the manner in which the basal planes of the haematite grains are arranged in the samples. The experimental results are interpreted on the basis of the single-domain theory. The proposed simple model of induced anisotropy is based on the relation between the directional susceptibility of the sample and the preferred orientation of the magnetic moments of the grains in polycrystalline haematite.
BibTeX:
@article{ref1,
  author = {Zapletal, Karel and Kropáček, V},
  title = {Magnetic anisotropy of polycrystalline haematite induced by A D. C. magnetic field},
  journal = {Studia Geophysica & Geodaetica},
  year = {1985},
  volume = {29},
  number = {4},
  pages = {351--361},
  url = {http://link.springer.com/10.1007/BF01641625},
  doi = {http://dx.doi.org/10.1007/BF01641625}
}
Hrouda, F. & Hanák, J. (1984), "Magnetic anisotropy of rocks of the Černá Hora and Branisko Mts. (in Czech)"; , Fyzikální vlastnosti hornin a jejich využití v geofyzice a geologii. ČSMG Praha
BibTeX:
@inproceedings{Hrouda1984,
  author = {Hrouda, František and Hanák, Jaromír},
  title = {Magnetic anisotropy of rocks of the Černá Hora and Branisko Mts. (in Czech)},
  booktitle = {Fyzikální vlastnosti hornin a jejich využití v geofyzice a geologii. ČSMG Praha},
  year = {1984}
}
Jelínek, V. (1984), "On a mixed quadratic invariant of the magnetic susceptibility tensor"; J. Geophys., Vol. 56 , pp. 58-60
BibTeX:
@article{Jelinek1984,
  author = {Jelínek, V},
  title = {On a mixed quadratic invariant of the magnetic susceptibility tensor},
  journal = {J. Geophys.},
  year = {1984},
  volume = {56},
  pages = {58--60}
}
Hrouda, F., Stephenson, A. & Woltär, L. (1983), "On the standardization of measurements of the anisotropy of magnetic susceptibility"; Physics of the Earth and Planetary Interiors, Vol. 32 (3) , pp. 203-208
Abstract: The magnetic anisotropy of several artificially constructed samples has been measured with different types of instruments in several laboratories. Susceptibility bridge determinations have given consistent results, but the magnitude of the anisotropy determined by the Digico anisotropy delineator is incorrect. For future measurements with this instrument it is necessary to make either a simple calibration change or to make a minor change in the associated computer program. A set of equations for correcting the old published data is given.
BibTeX:
@article{Hrouda1983,
  author = {Hrouda, František and Stephenson, Alan and Woltär, Leo},
  title = {On the standardization of measurements of the anisotropy of magnetic susceptibility},
  journal = {Physics of the Earth and Planetary Interiors},
  year = {1983},
  volume = {32},
  number = {3},
  pages = {203--208},
  url = {http://www.sciencedirect.com/science/article/pii/0031920183901255},
  doi = {http://dx.doi.org/10.1016/0031-9201(83)90125-5}
}
Hrouda, F. (1983), "Fabric implications of magnetic anisotropy measurements of rocks of the Malé Karpaty (Little Carpathians) Mts. (SW Slovakia)."; Annuaire Inst. Geol. Geophys., Bucharest, Vol. 63 , pp. 57-61
BibTeX:
@article{Hrouda1983a,
  author = {Hrouda, František},
  title = {Fabric implications of magnetic anisotropy measurements of rocks of the Malé Karpaty (Little Carpathians) Mts. (SW Slovakia).},
  journal = {Annuaire Inst. Geol. Geophys., Bucharest},
  year = {1983},
  volume = {63},
  pages = {57--61}
}
Hrouda, F., Kahan, S. & Putis, M. (1983), "The magnetic and mesoscopic fabrics of the crystalline complex of the Strazovske Vrchy Mts. and their tectonic implications."; , Vol. 34 (6)Geologica Carpathica , pp. 717-731
Abstract: In metamorphic rocks of the Strazovske Vrchy Mts. both the magnetic and the mesoscopic fabrics originated during the processes of deformation and recrystallization in an anisotropic stress field associated with Hercynian or older regional metamorphism. In granitoid rocks the magnetic fabric was formed partially by the intrusive movements and partially by plastic deformation due to the folding. -Authors
BibTeX:
@misc{Hrouda1983b,
  author = {Hrouda, František and Kahan, S and Putis, M},
  title = {The magnetic and mesoscopic fabrics of the crystalline complex of the Strazovske Vrchy Mts. and their tectonic implications.},
  booktitle = {Geologica Carpathica},
  year = {1983},
  volume = {34},
  number = {6},
  pages = {717--731},
  url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-0020918845&partnerID=tZOtx3y1}
}
Hrouda, F. & Rejl, L. (1982), "The small-scale magnetic susceptibility distribution in some plutonic rocks and its geological implications"; Vestnik ustredniho ustavu geologie, Vol. 57 , pp. 65-70
BibTeX:
@article{Hrouda1982,
  author = {Hrouda, František and Rejl, Luboš},
  title = {The small-scale magnetic susceptibility distribution in some plutonic rocks and its geological implications},
  journal = {Vestnik ustredniho ustavu geologie},
  year = {1982},
  volume = {57},
  pages = {65--70}
}
Hrouda, F. (1982), "Magnetic fabric changes during progressive metamorphism and deformation of flysch sediments"; Mitt. Geol. Inst. ETH and Univ. Zurich Neue Folge, Vol. 239a , pp. 136-139
BibTeX:
@article{Hrouda1982a,
  author = {Hrouda, František},
  title = {Magnetic fabric changes during progressive metamorphism and deformation of flysch sediments},
  journal = {Mitt. Geol. Inst. ETH and Univ. Zurich Neue Folge},
  year = {1982},
  volume = {239a},
  pages = {136--139}
}
Hrouda, F. (1982), "Magnetic anisotropy of rocks and its application in geology and geophysics"; Geophysical Surveys, Vol. 5 (1) , pp. 37-82
Abstract: Magnetic anisotropy in sedimentary rocks is controlled by the processes of deposition and compaction, in volcanic rocks by the lava flow and in metamorphic and plutonic rocks by ductile deformation and mimetic crystallization. In massive ore it is due to processes associated with emplacement and consolidation of an ore body as well as to ductile deformation. Hence, it can be used as a tool of structural analysis for almost all rock types. Moreover, it can influence considerably the orientation of the remanent magnetization vector as well as the configuration of a magnetic anomaly over a magnetized body. For these reasons it should be investigated in palaeomagnetism and applied geophysics as well.
BibTeX:
@article{Hrouda1982b,
  author = {Hrouda, František},
  title = {Magnetic anisotropy of rocks and its application in geology and geophysics},
  journal = {Geophysical Surveys},
  year = {1982},
  volume = {5},
  number = {1},
  pages = {37--82},
  doi = {http://dx.doi.org/10.1007/BF01450244}
}
Hrouda, F., Chlupáčová, M. & Konupčík, M. (1982), "Preferred orientation of the Zlaté Hory pyrrhotites by mineral lattice investigated by means of magnegtic anisotropy (in Czech)"; , KRB RRGPJ Loučná n/D , pp. 97-104
BibTeX:
@inproceedings{Hrouda1982c,
  author = {Hrouda, František and Chlupáčová, Marta and Konupčík, M},
  title = {Preferred orientation of the Zlaté Hory pyrrhotites by mineral lattice investigated by means of magnegtic anisotropy (in Czech)},
  booktitle = {KRB RRGPJ Loučná n/D},
  year = {1982},
  pages = {97--104}
}
Hrouda, F. (1981), "On the superposition of regional slaty cleavage on folded strata and its reflection in magnetic anisotropy"; Casopis pro mineralogii a geologii, Vol. 26 , pp. 341-348
BibTeX:
@article{Hrouda1981,
  author = {Hrouda, František},
  title = {On the superposition of regional slaty cleavage on folded strata and its reflection in magnetic anisotropy},
  journal = {Casopis pro mineralogii a geologii},
  year = {1981},
  volume = {26},
  pages = {341--348}
}
Hrouda, F. (1981), "On the mechanism of fold formation in the Nízký Jeseník (in Czech) Mts."; Věst. Ústř. Úst. Geol., Vol. 56 , pp. 271-278
BibTeX:
@article{Hrouda1981a,
  author = {Hrouda, František},
  title = {On the mechanism of fold formation in the Nízký Jeseník (in Czech) Mts.},
  journal = {Věst. Ústř. Úst. Geol.},
  year = {1981},
  volume = {56},
  pages = {271--278}
}
Jelínek, V. (1981), "Characterization of the magnetic fabric of rocks"; Tectonophysics, Vol. 79 (3-4) , pp. T63-T67
Abstract: An inextensive system of magnetic susceptibility anisotropy factors is suggested which is sufficient in the majority of practical applications for characterizing the magnetic fabric of rocks. The system involves three newly devised factors: the corrected anisotropy degree, the shape factor and the difference shape factor. The first of these characterizes the quantity of anisotropy somewhat better than the commonly used anisotropy degree. The shape factor characterizes the quality of anisotropy i.e. the shape of the susceptibility ellipsoid, in a convenient way; its definition is based on a certain analogy between the anisotropy ellipsoid and the strain ellipsoid. The difference shape factor can replace the shape factor when only the differences between the principal susceptibilities are given while the mean susceptibility is unknown.
BibTeX:
@article{Jelinek1981,
  author = {Jelínek, V},
  title = {Characterization of the magnetic fabric of rocks},
  journal = {Tectonophysics},
  year = {1981},
  volume = {79},
  number = {3-4},
  pages = {T63--T67},
  url = {http://www.sciencedirect.com/science/article/pii/0040195181901104},
  doi = {http://dx.doi.org/10.1016/0040-1951(81)90110-4}
}
Kapička, A. & Hrouda, F. (1981), "Changes of anisotropy of the magnetic susceptibility of rocks induced by a magnetic field"; Studia Geophysica et Geodaetica, Vol. 25 (3) , pp. 262-274
Abstract: The changes of the anisotropy of magnetic susceptibility of igneous rocks, induced by a magnetic field, are studied. It is proved that changes in the degree of anisotropy of susceptibility and of the orientation of the susceptibility ellispoid of specimens occur due to the configuration of the domain structure under the effect of the magnetic field. The influence of this effect on the total anisotropy of rocks depends on the degree of anisotropy due to the shape factor and on the stability of the domain structure. A model concept is presented, explaining the qualitatively different pattern of the changes of the anisotropy of susceptibility under the effect of the magnetic field in various directions of the specimens. textcopyright 1981 ACADEMIA Publishing House of the Czechoslovak Academy of Sciences.
BibTeX:
@article{Kapicka1981,
  author = {Kapička, Aleš and Hrouda, František},
  title = {Changes of anisotropy of the magnetic susceptibility of rocks induced by a magnetic field},
  journal = {Studia Geophysica et Geodaetica},
  year = {1981},
  volume = {25},
  number = {3},
  pages = {262--274},
  doi = {http://dx.doi.org/10.1007/BF01591937}
}
Hrouda, F. & Chlupáčová, M. (1980), "The magnetic fabric in the Nasavrky massif"; Miner. Geol., Vol. 25 , pp. 17-27
BibTeX:
@article{Hrouda1980,
  author = {Hrouda, František and Chlupáčová, Marta},
  title = {The magnetic fabric in the Nasavrky massif},
  journal = {Miner. Geol.},
  year = {1980},
  volume = {25},
  pages = {17--27}
}
Hrouda, F. (1980), "Magnetocrystalline anisotropy of rocks and massive ores: A mathematical model study and its fabric implications"; Journal of Structural Geology, Vol. 2 (4) , pp. 459-462
Abstract: A simple mathematical model has been used to evaluate the influence of grain magnetocrystalline anisotropy and the scatter of crystallographic axes of grains on the magnetic anisotropy of rocks and massive ores whose carrier of magnetism is a magnetically uniaxial mineral of the type of pyrrhotite or hematite. The variation in magnetic anisotropy of rocks and ores whose carrier of magnetism displays the magnetocrystalline anisotropy greater than 100 is due to the variation in the preferred orientations of crystallographic axes, while the influence of the variation in the grain anisotropy on the rock (ore) anisotropy can be neglected.
BibTeX:
@article{Hrouda1980,
  author = {Hrouda, František},
  title = {Magnetocrystalline anisotropy of rocks and massive ores: A mathematical model study and its fabric implications},
  journal = {Journal of Structural Geology},
  year = {1980},
  volume = {2},
  number = {4},
  pages = {459--462},
  url = {http://www.sciencedirect.com/science/article/pii/0191814180900073},
  doi = {http://dx.doi.org/10.1016/0191-8141(80)90007-3}
}
Hrouda, F. (1980), "Development of ductile deformation in rocks of the Nízký Jeseník Mts., investigated through magnetic anisotropy (in Czech)"; Geol. průzk., Vol. 8 , pp. 232-234
BibTeX:
@article{Hrouda1980a,
  author = {Hrouda, František},
  title = {Development of ductile deformation in rocks of the Nízký Jeseník Mts., investigated through magnetic anisotropy (in Czech)},
  journal = {Geol. průzk.},
  year = {1980},
  volume = {8},
  pages = {232--234}
}
Hrouda, F. (1980), "Magnetic anisotropy in the NE part of the Bohemian massif"; , Int. Conf. "Bohemian massif"
BibTeX:
@inproceedings{Hrouda1980b,
  author = {Hrouda, František},
  title = {Magnetic anisotropy in the NE part of the Bohemian massif},
  booktitle = {Int. Conf. "Bohemian massif"},
  year = {1980}
}
Hrouda, F. & Chlupáčová, M. (1980), "Magnetic anisotropy of massive ores and its use in economic geology (in Czech)"; , Sbor. ref. 7. celost. konf. geol. Gottwaldov, Sekce S3 , pp. 57-59
BibTeX:
@inproceedings{Hrouda1980c,
  author = {Hrouda, František and Chlupáčová, Marta},
  title = {Magnetic anisotropy of massive ores and its use in economic geology (in Czech)},
  booktitle = {Sbor. ref. 7. celost. konf. geol. Gottwaldov, Sekce S3},
  year = {1980},
  pages = {57--59}
}
Hrouda, F. (1979), "The strain interpretation of magnetic anisotropy in rocks of the Nizky Jesenik Mountains (Czechoslovakia)"; Sbor. geol. Věd, řada UG, Vol. 16 , pp. 27-62
BibTeX:
@article{Hrouda1979,
  author = {Hrouda, František},
  title = {The strain interpretation of magnetic anisotropy in rocks of the Nizky Jesenik Mountains (Czechoslovakia)},
  journal = {Sbor. geol. Věd, řada UG},
  year = {1979},
  volume = {16},
  pages = {27--62}
}
Hrouda, F. (1979), "Magnetic anisotropy and plastic deformation in metamorphic rocks"; , Geodynamic Investigations in Czechoslovakia , pp. 271-275, Veda Bratislava
Abstract: The research into the magnetic anisotropy of metamorphic rocks has disclosed a close relation between magnetic anisotropy and plastic deformation of rocks. Consequently, after determining all the details of this relation, magnetic anisotropy has a good chance of becoming an effective tool in deformation analysis of metamorphic rocks. -from Author
BibTeX:
@inbook{Hrouda1979a,
  author = {Hrouda, František},
  title = {Magnetic anisotropy and plastic deformation in metamorphic rocks},
  booktitle = {Geodynamic Investigations in Czechoslovakia},
  publisher = {Veda Bratislava},
  year = {1979},
  pages = {271--275}
}
Hrouda, F. (1979), "Petromagnetic determination od palaeocurrents in sediments of the Hradec-Kyjovice Formation of the Nízký Jeseník Mts. (in Czech)"; Geol. průzk., Vol. 11 , pp. 324-326
BibTeX:
@article{Hrouda1979c,
  author = {Hrouda, František},
  title = {Petromagnetic determination od palaeocurrents in sediments of the Hradec-Kyjovice Formation of the Nízký Jeseník Mts. (in Czech)},
  journal = {Geol. průzk.},
  year = {1979},
  volume = {11},
  pages = {324--326}
}
Blížkovský, M., Hrouda, F., Kadlec, E. et al. (1978), "Investigation of chromite deposits by geophysical methods."; , Inter. geophys. symp., Varna , pp. 447-459
BibTeX:
@inproceedings{Blizkovsky1978,
  author = {Blížkovský, M and Hrouda, František and Kadlec, E and Pícha, B},
  title = {Investigation of chromite deposits by geophysical methods.},
  booktitle = {Inter. geophys. symp., Varna},
  year = {1978},
  pages = {447--459}
}
Hrouda, F., Janák, F. & Rejl, L. (1978), "Magnetic anisotropy and ductile deformation of rocks in zones of progressive regional metamorphism"; Gerl. Beitr. Geophys., Vol. 87 , pp. 126-134
BibTeX:
@article{Hrouda1978,
  author = {Hrouda, František and Janák, František and Rejl, Luboš},
  title = {Magnetic anisotropy and ductile deformation of rocks in zones of progressive regional metamorphism},
  journal = {Gerl. Beitr. Geophys.},
  year = {1978},
  volume = {87},
  pages = {126--134}
}
Hrouda, F. (1978), "The magnetic fabric in some folds"; Physics of the Earth and Planetary Interiors, Vol. 17 (2) , pp. 89-97
Abstract: Five folds are described, differing in terms of the relation of the magnetic fabric to the fold curve. The magnetic fabric study enables the time relationship between the magnetic fabric generation and the folding to be determined. In some cases the origin of folds can be studied.
BibTeX:
@article{Hrouda1978a,
  author = {Hrouda, František},
  title = {The magnetic fabric in some folds},
  journal = {Physics of the Earth and Planetary Interiors},
  year = {1978},
  volume = {17},
  number = {2},
  pages = {89--97},
  url = {http://www.sciencedirect.com/science/article/pii/003192017890050X},
  doi = {http://dx.doi.org/10.1016/0031-9201(78)90050-X}
}
Jelínek, V. & Kropáček, V. (1978), "Statistical processing of anisotropy of magnetic susceptibility measured on groups of specimens"; Studia Geophysica et Geodaetica, Vol. 22 (1) , pp. 50-62
Abstract: The theory of multivariate statistical processing of the anisotropy of magnetic susceptibility, measured on a group of specimens, originating from a single geological body (outcrop, locality, etc.), is described. The result of the processing is an estimate of the mean normalized tensor and the estimates of the principal susceptibilities, derived from it, together with the respective intervals of confidence, and the estimates of the principal directions with the respective regions of confidence. An anisotropy test for a group of specimens is proposed. The function of the ANS21 computer program employed is briefly described and an example of its output plot is presented.
BibTeX:
@article{ref1,
  author = {Jelínek, V and Kropáček, V},
  title = {Statistical processing of anisotropy of magnetic susceptibility measured on groups of specimens},
  journal = {Studia Geophysica et Geodaetica},
  year = {1978},
  volume = {22},
  number = {1},
  pages = {50--62},
  url = {http://link.springer.com/10.1007/BF01613632},
  doi = {http://dx.doi.org/10.1007/BF01613632}
}
Štelcl, J., Hrouda, F. & Janák, F. (1978), "Petrophysics in geological sciences (in Czech)"; , Scripta Fac. Sci.Natur. UJEP Brunensis, Geologia 2 , pp. 67-76
BibTeX:
@incollection{Stelcl1978,
  author = {Štelcl, J and Hrouda, František and Janák, František},
  title = {Petrophysics in geological sciences (in Czech)},
  booktitle = {Scripta Fac. Sci.Natur. UJEP Brunensis, Geologia 2},
  year = {1978},
  pages = {67--76}
}
Jelínek, V. (1977), "The statistical theory of measuring anisotropy of magnetic susceptibility of rocks and its application"; , , Geofyzika, s.p., Brno
BibTeX:
@book{Jelinek1977,
  author = {Jelínek, V},
  title = {The statistical theory of measuring anisotropy of magnetic susceptibility of rocks and its application},
  publisher = {Geofyzika, s.p., Brno},
  year = {1977},
  url = {http://www.agico.com/downloads/documents/agicoprints/statistical_theory.pdf}
}
Zapletal, K. (1977), "Mossbauer spectra of magnetites from serpentinites"; , Proc. Int. Conf. Mossbauer spectroscopy , pp. 317-318
BibTeX:
@inproceedings{Zapletal1977,
  author = {Zapletal, Karel},
  title = {Mossbauer spectra of magnetites from serpentinites},
  booktitle = {Proc. Int. Conf. Mossbauer spectroscopy},
  year = {1977},
  pages = {317--318}
}
Hrouda, F. & Janák, F. (1976), "The changes in shape of the magnetic susceptibility ellipsoid during progressive metamorphism and deformation"; Tectonophysics, Vol. 34 (1-2) , pp. 135-148
Abstract: The magnetic anisotropy of a sequence of rocks ranging from shales and greywackes to gneisses was investigated. The oblate and slightly eccentric magnetic susceptibility ellipsoids in sediments are progressively changed when sediments are subject to metamorphism and ductile deformation. In the initial stages of low-grade metamorphism and ductile deformation, the ellipsoids become more eccentric and triaxial, later they are even more eccentric, but again predominantly oblate. The directions of principal susceptibilities are closely related to the primary-fabric elements in undeformed sediments; during deformation they come to be related to the deformational-fabric elements.
BibTeX:
@article{Hrouda1976,
  author = {Hrouda, František and Janák, František},
  title = {The changes in shape of the magnetic susceptibility ellipsoid during progressive metamorphism and deformation},
  journal = {Tectonophysics},
  year = {1976},
  volume = {34},
  number = {1-2},
  pages = {135--148},
  url = {http://www.sciencedirect.com/science/article/pii/0040195176901815},
  doi = {http://dx.doi.org/10.1016/0040-1951(76)90181-5}
}
Hrouda, F. (1976), "The origin of cleavage in the light of magnetic anisotropy investigations"; Physics of the Earth and Planetary Interiors, Vol. 13 (2) , pp. 132-142
Abstract: The cleavage origin in rocks ranging from unmetamorphosed sediments, through slates to phyllites of the Nízký Jeseník Mts. (northern Moravia, Czechoslovakia), which show a range of deformation styles, from undeformed through fracture and slaty cleavage to the development of metamorphic foliation, was studied by means of magnetic anisotropy. These studies have shown that the fracture cleavage probably originated during a post-plastic rock deformation. Therefore the orientation of the fracture cleavage with respect to the strain-tensor components cannot be studied by means of magnetic anisotropy. The magnetic fabric of rocks with slaty cleavage was generated through componental movements during the ductile rock deformation. The slaty cleavage developed perpendicularly to the maximum shortening direction. In the rocks exhibiting macroscopically observable marks of slippage along the slaty cleavage, the slippage probably took place after the slaty cleavage developed, when the rock ductility was lower. The metamorphic foliation developed from the slaty cleavage in the course of continuous strain.
BibTeX:
@article{Hrouda1976a,
  author = {Hrouda, František},
  title = {The origin of cleavage in the light of magnetic anisotropy investigations},
  journal = {Physics of the Earth and Planetary Interiors},
  year = {1976},
  volume = {13},
  number = {2},
  pages = {132--142},
  url = {http://www.sciencedirect.com/science/article/pii/0031920176900789},
  doi = {http://dx.doi.org/10.1016/0031-9201(76)90078-9}
}
Hrouda, F. (1976), "A model for the orientation process of ferromagnetic minerals in slates"; Earth and Planetary Science Letters, Vol. 33 (1) , pp. 107-110
Abstract: The orientation mechanism of ferromagnetic mineral grains in deforming slates (strain response model) was studied on the basis of a comparison of the degrees of magnetic anisotropy in natural slates with those calculated for the “line/plane” and “passive” models. Ferromagnetic grains reorientate mostly as rigid particles in a ductile matrix, although the possibility of a subordinate change in shape cannot be excluded.
BibTeX:
@article{Hrouda1976b,
  author = {Hrouda, František},
  title = {A model for the orientation process of ferromagnetic minerals in slates},
  journal = {Earth and Planetary Science Letters},
  year = {1976},
  volume = {33},
  number = {1},
  pages = {107--110},
  url = {http://www.sciencedirect.com/science/article/pii/0012821X7690162X},
  doi = {http://dx.doi.org/10.1016/0012-821X(76)90162-X}
}
Chlupáčová, M., Hrouda, F., Janák, F. et al. (1975), "The fabric, genesis, and relative-age relationship of the granitic rocks of the cista - Jesenice massif, as studied by magnetic anisotropy"; Gerl. Beitr. Geophys., Vol. 84 , pp. 487-500
BibTeX:
@article{Chlupacova1975,
  author = {Chlupáčová, Marta and Hrouda, František and Janák, František and Rejl, Luboš},
  title = {The fabric, genesis, and relative-age relationship of the granitic rocks of the cista - Jesenice massif, as studied by magnetic anisotropy},
  journal = {Gerl. Beitr. Geophys.},
  year = {1975},
  volume = {84},
  pages = {487--500}
}
Dvořák, J. & Hrouda, F. (1975), "The reflection of the deeper structure of the Artmanov - Osoblaha block (Nizky Jesenik Mountains, Czechoslovakia) in magnetic anisotropy and deformation history of overlying Palaeozoic sediments"; Vestnik ustredniho ustavu geologie, Vol. 50 , pp. 285-296
BibTeX:
@article{Dvorak1975,
  author = {Dvořák, J and Hrouda, František},
  title = {The reflection of the deeper structure of the Artmanov - Osoblaha block (Nizky Jesenik Mountains, Czechoslovakia) in magnetic anisotropy and deformation history of overlying Palaeozoic sediments},
  journal = {Vestnik ustredniho ustavu geologie},
  year = {1975},
  volume = {50},
  pages = {285--296}
}
Hrouda, F. (1975), "Archaeomagnetic age determination of archaeological materials from oxidation burned soil (in Czech)"; , Pffafenschlag, zaniklá středověká ves u Slavonic , pp. 219-221, Blok, Brno
BibTeX:
@incollection{Hrouda1975,
  author = {Hrouda, František},
  title = {Archaeomagnetic age determination of archaeological materials from oxidation burned soil (in Czech)},
  booktitle = {Pffafenschlag, zaniklá středověká ves u Slavonic},
  publisher = {Blok, Brno},
  year = {1975},
  pages = {219--221}
}
Hrouda, F. (1975), "Magnetic anisotropy and deformation of rocks (in Czech)"; , Sbor. 6. celost. konf. geofyziků, Plzeň , pp. 363-372
BibTeX:
@inproceedings{Hrouda1975a,
  author = {Hrouda, František},
  title = {Magnetic anisotropy and deformation of rocks (in Czech)},
  booktitle = {Sbor. 6. celost. konf. geofyziků, Plzeň},
  year = {1975},
  pages = {363--372}
}
Hrouda, F., Janák, F. & Štelcl, J. (1974), "Locality No. 3 - Blansko, Locality No. 4 - Lhota Rapotina"; , Excursion profile through granodiorites of the Brno massif , pp. 12-18, UJEP Brno
BibTeX:
@incollection{Hrouda1974,
  author = {Hrouda, František and Janák, František and Štelcl, J},
  title = {Locality No. 3 - Blansko, Locality No. 4 - Lhota Rapotina},
  booktitle = {Excursion profile through granodiorites of the Brno massif},
  publisher = {UJEP Brno},
  year = {1974},
  pages = {12--18}
}
Štelcl, J., Schmidt, J. & Hrouda, F. (1974), "Fabric study problems of the Brno massif"; Sbor. geol. Věd, řada UG, Vol. 26 , pp. 177-184
BibTeX:
@article{Stelcl1974,
  author = {Štelcl, J and Schmidt, J and Hrouda, František},
  title = {Fabric study problems of the Brno massif},
  journal = {Sbor. geol. Věd, řada UG},
  year = {1974},
  volume = {26},
  pages = {177--184}
}
Hrouda, F. (1973), "A determination of the symmetry of the ferromagnetic mineral fabric in rocks on the basis of the magnetic susceptibility anisotropy measurements"; Gerl. Beitr. Geophys., Vol. 82 , pp. 390-396
BibTeX:
@article{Hrouda1973,
  author = {Hrouda, František},
  title = {A determination of the symmetry of the ferromagnetic mineral fabric in rocks on the basis of the magnetic susceptibility anisotropy measurements},
  journal = {Gerl. Beitr. Geophys.},
  year = {1973},
  volume = {82},
  pages = {390--396}
}
Hrouda, F. & Rejl, L. (1973), "Investigation of the tectonics of the Brno massif based on magnetometric survey (In Czech)"; Věst. Ústř. Úst. Geol., Vol. 48 , pp. 1-9
BibTeX:
@article{Hrouda1973a,
  author = {Hrouda, František and Rejl, Luboš},
  title = {Investigation of the tectonics of the Brno massif based on magnetometric survey (In Czech)},
  journal = {Věst. Ústř. Úst. Geol.},
  year = {1973},
  volume = {48},
  pages = {1--9}
}
Hrouda, F. & Janák, F. (1973), "The use of magnetic anisotropy in the study of the current directions in sediments and lavas"; , Proc. X Congress of CGBA, sec. 8 geophysics , pp. 28-34
BibTeX:
@inproceedings{Hrouda1973b,
  author = {Hrouda, František and Janák, František},
  title = {The use of magnetic anisotropy in the study of the current directions in sediments and lavas},
  booktitle = {Proc. X Congress of CGBA, sec. 8 geophysics},
  year = {1973},
  pages = {28--34}
}
Jelínek, V. & Bucha, V. (1973), "Precision A.C. bridge set for measuring magnetic susceptibility of rocks and its anisotropy"; Studia Geophysica et Geodaetica, Vol. 17 (1) , pp. 36-48
Abstract: A bridge set for measuring the magnetic susceptibility of rocks and its anisotropy is described. The classical transformer bridge has been supplemented with an auxiliary compensating arm for balancing the bridge without any mechanical infringement of the measuring coils. By employing this principle and the appropriate methods a sensitivityof 4 texttimes 10 −8 SI units (3 texttimes 10 −9 e.m.u./cm3) has been achieved for a sample of 8 cm3 in volume. In addition to its high sensitivity the device has a considerable accuracy, which makes it suitable for susceptibility anisotropy measurements even of samples with a very low susceptibility and only slight anisotropy. Well-reproducible results have been achieved for samples with a mean susceptibility of the order of10 −5 SI units with an anisotropy degree of only about 1.05.
BibTeX:
@article{ref1,
  author = {Jelínek, V and Bucha, V},
  title = {Precision A.C. bridge set for measuring magnetic susceptibility of rocks and its anisotropy},
  journal = {Studia Geophysica et Geodaetica},
  year = {1973},
  volume = {17},
  number = {1},
  pages = {36--48},
  url = {http://link.springer.com/10.1007/BF01614027},
  doi = {http://dx.doi.org/10.1007/BF01614027}
}
Dvořák, J. & Hrouda, F. (1972), "The origin of tectonic structures in weakly metamorphosed sediments, as studied by magnetic anisotropy"; N. Jb. Geol. Palaont. Mh., Vol. 12 , pp. 703-712
BibTeX:
@article{Dvorak1972,
  author = {Dvořák, J and Hrouda, František},
  title = {The origin of tectonic structures in weakly metamorphosed sediments, as studied by magnetic anisotropy},
  journal = {N. Jb. Geol. Palaont. Mh.},
  year = {1972},
  volume = {12},
  pages = {703--712}
}
Hrouda, F., Chlupáčová, M. & Rejl, L. (1972), "Changes in the magnetite content and magnetite fabric during fenitization, as investigated by petromagnetic methods."; N. Jb. Miner. Abh., Vol. 117 , pp. 61-72
BibTeX:
@article{Hrouda1972,
  author = {Hrouda, František and Chlupáčová, Marta and Rejl, Luboš},
  title = {Changes in the magnetite content and magnetite fabric during fenitization, as investigated by petromagnetic methods.},
  journal = {N. Jb. Miner. Abh.},
  year = {1972},
  volume = {117},
  pages = {61--72}
}
Hrouda, F. (1972), "On the use of magnetic anisotropy in geology and petrology of sedimentary rocks (in Czech)"; Geol. průzk., Vol. 14 , pp. 71-72
BibTeX:
@article{Hrouda1972a,
  author = {Hrouda, František},
  title = {On the use of magnetic anisotropy in geology and petrology of sedimentary rocks (in Czech)},
  journal = {Geol. průzk.},
  year = {1972},
  volume = {14},
  pages = {71--72}
}
Zapletal, K. & Janák, F. (1972), "On the magnetic phases of natural pyrrhotites"; Studia Geophysica et Geodaetica, Vol. 16 (2) , pp. 167-176
Abstract: The magnetic phases of natural pyrrhotites were studied by the method of powder patterns, the chemism of the magnetic phases by means of the electron microprobe method, and the crystal phases by etching the polished sections. The method of powder patterns distinguished the ferrimagnetic and antiferromagnetic phases in the transition-type pyrrhotites. The method of absorbed electrons lead to the discovery that both phases have a different chemical composition and that the ferrimagnetic phase has a lower denisty and an average atomic number. The linear and point-by-point analysis disclosed that the ferrimagnetic phase has a lower weight content of Fe and a higher weight content of S than the antiferromagnetic phase. Both the magnetic phases displayed different properties when etched, and therefore they not only have a different chemical composition, but also a different crystal structure. The necessity of studying the image of the absorbed electrons and the image of the etched surface of the polycrystalline samples of pyrrhotites of the transition type separately on individual grains was pointed out.
BibTeX:
@article{ref1,
  author = {Zapletal, Karel and Janák, František},
  title = {On the magnetic phases of natural pyrrhotites},
  journal = {Studia Geophysica et Geodaetica},
  year = {1972},
  volume = {16},
  number = {2},
  pages = {167--176},
  url = {http://link.springer.com/10.1007/BF01614513},
  doi = {http://dx.doi.org/10.1007/BF01614513}
}
Hrouda, F., Janák, F., Rejl, L. et al. (1971), "The use of magnetic susceptibility anisotropy for estimating the ferromagnetic mineral fabrics of metamorphic rocks"; Geologische Rundschau, Vol. 60 (3) , pp. 1124-1142
BibTeX:
@article{Hrouda1971,
  author = {Hrouda, František and Janák, František and Rejl, Luboš and Weiss, J},
  title = {The use of magnetic susceptibility anisotropy for estimating the ferromagnetic mineral fabrics of metamorphic rocks},
  journal = {Geologische Rundschau},
  year = {1971},
  volume = {60},
  number = {3},
  pages = {1124--1142},
  doi = {http://dx.doi.org/10.1007/BF02046539}
}
Hrouda, F., Chlupáčová, M. & Rejl, L. (1971), "The mimetic fabric of magnetite in some foliated granodiorites, as indicated by magnetic anisotropy"; Earth and Planetary Science Letters, Vol. 11 (1-5) , pp. 381-384
Abstract: The magnetite fabric of some foliated granodiorites of theČistástock was investigated by means of magnetic anisotropy. These investigations have shown that the magnetite in the rocks studied belongs to the demonstrably youngest minerals and its fabric was determined by the granodiorite fabric elements already present in these rocks. When originating, the magnetite imitated and considerably: intensified these elements so that their intensity and orientation can be studied by means of the magnetic anisotropy.
BibTeX:
@article{Hrouda1971a,
  author = {Hrouda, František and Chlupáčová, Marta and Rejl, Luboš},
  title = {The mimetic fabric of magnetite in some foliated granodiorites, as indicated by magnetic anisotropy},
  journal = {Earth and Planetary Science Letters},
  year = {1971},
  volume = {11},
  number = {1-5},
  pages = {381--384},
  url = {http://www.sciencedirect.com/science/article/pii/0012821X71901981},
  doi = {http://dx.doi.org/10.1016/0012-821X(71)90198-1}
}
Hrouda, F. (1971), "The magnetite fabric of some massive and mylonitized granodiorites of the most northern part of the Brno massif"; Miner. Geol., Vol. 16 , pp. 37-45
BibTeX:
@article{Hrouda1971b,
  author = {Hrouda, František},
  title = {The magnetite fabric of some massive and mylonitized granodiorites of the most northern part of the Brno massif},
  journal = {Miner. Geol.},
  year = {1971},
  volume = {16},
  pages = {37--45}
}
Hrouda, F. & Janák, F. (1971), "A study of the Hematite fabric of some red sediments on the basis of their magnetic susceptibility anisotropy"; Sedimentary Geology, Vol. 6 (3) , pp. 187-199
Abstract: The hematite fabric of some red sediments, in which hematite is the only ferromagnetic mineral, has been investigated by means of magnetic susceptibility anisotropy. It has been found that the symmetry of hematite in the sediments studied is mostly axial, the basal planes of hematite grains are parallel to beds, and the hematite fabric originated under the predominant influence of the earth's gravity field. It has also been found that the maximum susceptibility plane can be regarded as the bedding plane for badly bedded sediments.
BibTeX:
@article{Hrouda1971c,
  author = {Hrouda, František and Janák, František},
  title = {A study of the Hematite fabric of some red sediments on the basis of their magnetic susceptibility anisotropy},
  journal = {Sedimentary Geology},
  year = {1971},
  volume = {6},
  number = {3},
  pages = {187--199},
  url = {http://www.sciencedirect.com/science/article/pii/0037073871900352},
  doi = {http://dx.doi.org/10.1016/0037-0738(71)90035-2}
}
Hrouda, F. (1970), "The relation between the fabric and anisotropy of magnetic susceptibility for some West Moravian gneisses"; Vestnik ustredniho ustavu geologie, Vol. 45 , pp. 147-156
BibTeX:
@article{Hrouda1970,
  author = {Hrouda, František},
  title = {The relation between the fabric and anisotropy of magnetic susceptibility for some West Moravian gneisses},
  journal = {Vestnik ustredniho ustavu geologie},
  year = {1970},
  volume = {45},
  pages = {147--156}
}
Hrouda, F., Janák, F. & Štelcl, J. (1970), "Ueber die Verwendbarkeit der Anisotropie der magnetischen Suszeptibilitaet zur Bestimmung der Magnetitorientierung"; , Experimental and natural rock deformation , pp. 253-262, Springer Verlag Berlin
BibTeX:
@inbook{Hrouda1970a,
  author = {Hrouda, František and Janák, František and Štelcl, J},
  title = {Ueber die Verwendbarkeit der Anisotropie der magnetischen Suszeptibilitaet zur Bestimmung der Magnetitorientierung},
  booktitle = {Experimental and natural rock deformation},
  publisher = {Springer Verlag Berlin},
  year = {1970},
  pages = {253--262}
}
Hrouda, F. (1969), "Anisotropy of magnetic susceptibility of rocks and its significance for petrotectonics (in Czech)"; Čas. miner. geol., Vol. 14 , pp. 119-124
BibTeX:
@article{Hrouda1969,
  author = {Hrouda, František},
  title = {Anisotropy of magnetic susceptibility of rocks and its significance for petrotectonics (in Czech)},
  journal = {Čas. miner. geol.},
  year = {1969},
  volume = {14},
  pages = {119--124}
}
Zapletal, K. (1969), "Connection of some magnetic properties with the phase composition of natural pyrrhotites"; Studia Geophysica et Geodaetica, Vol. 13 (2) , pp. 191-198
Abstract: Es wurde der Zusammenhang zwischen einigen magnetischen Eigenschaften und der Phasenstruktur von Naturpyrrhotinen aus 19 überwiegend tschechoslovakischen Lokalitäten studiert. Mit der Methode der Staubfiguren wurde die Domänenstruktur und Phasenzusammensetzung von Naturpyrrhotinen im ursprünglichen Zustand und nach der Glühung im Vakuum festgestellt. Weiter wurde die spezifische Magnetisierung (im magnetischen Aussenfeld von 9500 Oe) und ihre Temperaturabhängigkeit gemessen. Man hat festgestellt, dass der grosse Streubereich von Werten der spezifischen MagnetisierungJ 20textdegreeC 9500Oe (2,0--18,8 Gcm3/g) durch verschiedenen Relativgehalt der ferrimagnetischen und antiferromagnetischen Phase in einzelnen Proben verursacht ist. Die untersuchten Pyrrhotine kann man in zwei Gruppen teilen, u.zw.in: 1) Rein ferrimagnetische Pyrrhotine. Die spezifische MagnetisierungJ 20textdegreeC 9500Oe hat die Werte von 16,5--18,8 Gcm3/g. Die thermomagnetischen Kurven sind von normaler Néelschen Form. 2) Pyrrhotine des Übergangstyps, welche die ferrimagnetische und antiferromagnetische Phase enthalten. Die Werte der spezifischen MagnetisierungJ 20textdegreeC 9500Oe sind niedriger als beiläufig 16,5 Gem3/g und sie sinken mit dem sich verkleinernden Relativgehalt der ferrimagnetischen Phase in den Proben. Die thermomagnetischen Kurven sind von $-Typ. Die Werte der spezifischen MagnetisierungJ 9500Oe(T) sind bei der Abkühlung wesentlich höher als bei der Erwärmung (die Erwärmungs- und Abkühlungsgeschwindigkeit war 10textdegreeC/Min., die Maximaltemperatur der Erwärmung betrug 400textdegreeC). Die wesentliche Erhöhung der spezifischen Magnetisierung der Pyrrhotine vom Übergangstyp ($-Typ) nach der Glühung bei 400textdegreeC wird vor allem durch die Phasenveränderungen in der antiferromagnetischen Phase verursacht. An einigen Stellen der ursprünglich antiferromagnetischen Phase bildet sich bei der Glühung die ferrimagnetische Phase.
BibTeX:
@article{ref1,
  author = {Zapletal, Karel},
  title = {Connection of some magnetic properties with the phase composition of natural pyrrhotites},
  journal = {Studia Geophysica et Geodaetica},
  year = {1969},
  volume = {13},
  number = {2},
  pages = {191--198},
  url = {http://link.springer.com/10.1007/BF02587820},
  doi = {http://dx.doi.org/10.1007/BF02587820}
}
Hrouda, F., Janák, F. & Štelcl, J. (1968), "Zur petrophysikalischen Charakteristik einiger Granodiorite des Brunner Massivs"; Gerl. Beitr. Geophys., Vol. 77 , pp. 473-486
BibTeX:
@article{Hrouda1968,
  author = {Hrouda, František and Janák, František and Štelcl, J},
  title = {Zur petrophysikalischen Charakteristik einiger Granodiorite des Brunner Massivs},
  journal = {Gerl. Beitr. Geophys.},
  year = {1968},
  volume = {77},
  pages = {473--486}
}
Hrouda, F., Janák, F. & Štelcl, J. (1967), "On the study of magnetic susceptibility of some granodiorites of the Brno massif (In Czech)."; Zpráv. geol. výzk.,, , pp. 44-45
BibTeX:
@article{Hrouda1967,
  author = {Hrouda, František and Janák, František and Štelcl, J},
  title = {On the study of magnetic susceptibility of some granodiorites of the Brno massif (In Czech).},
  journal = {Zpráv. geol. výzk.,},
  year = {1967},
  pages = {44--45}
}
Jelínek, V. (1966), "A high sensitivity spinner magnetometer"; Studia Geophysica et Geodaetica, Vol. 10 (1) , pp. 58-78
Abstract: Описявается чувствительный рок-генератор для измерения слабой остаточной магнитной поляризации горных пород, предназначенный прежде всего для палеомагнитных исследований. Датчиком прибора является система двух плоских катушек, похожая на систему Гельмгольца. Датчик магнитно экранирован трехкратным пермаллоевым кожухом. Образец горной породы в виде куба с ребром длиной в 20мм врашается внутри датчика со скоростью 85об/сек. Одновременно измеряются косинусоидальная и синусоидальная слагающие индуцированного в датчике напряжения; для выпрямления применяются два синхронных демодулятора. Измеряемые слагающие напряжения пропорциональны двум слагающим вектора остаточной магнитной поляризации. Для определения всех трех слагаюших вектора надо провести хотя бы два измерения образца в двух положениях (но на самом деле образец измеряют в 6 положениях). Чувствительность прибора---5нтг, те. 4. 10−9 единиц системы ЦГСМ. В статье тоже приведена краткая обшая теория чувствительности рок-генераторов.
BibTeX:
@article{ref1,
  author = {Jelínek, V},
  title = {A high sensitivity spinner magnetometer},
  journal = {Studia Geophysica et Geodaetica},
  year = {1966},
  volume = {10},
  number = {1},
  pages = {58--78},
  url = {http://link.springer.com/10.1007/BF02590052},
  doi = {http://dx.doi.org/10.1007/BF02590052}
}
Hrouda, F. (1964), "On the use of palaeomagnetism in speleology (in Czech)."; Kras v ČSSR, , pp. 13-17
BibTeX:
@article{Hrouda1964,
  author = {Hrouda, František},
  title = {On the use of palaeomagnetism in speleology (in Czech).},
  journal = {Kras v ČSSR},
  year = {1964},
  pages = {13--17}
}
Bartošek, J. & Jelínek, V. (1961), "Portable instrument for measuring magnetic susceptibility of rocks in situ (kappa-meter) (in Czech)"; Geol. průzk., , pp. 374-376
BibTeX:
@article{Bartosek1961,
  author = {Bartošek, Jiří and Jelínek, V},
  title = {Portable instrument for measuring magnetic susceptibility of rocks in situ (kappa-meter) (in Czech)},
  journal = {Geol. průzk.},
  year = {1961},
  pages = {374--376}
}

AGICO, Inc, Brno, Czech Republic

ROCK MAGNETISM MEASUREMENTS WITH TRADITION

Last update >>> 06/2017