RESEARCH & DEVELOPMENT

Because AGICO's customers are almost exclusively universities and other scientific institutions, it is useful not only to do engineering work in developing instruments, but also to pursue research into rock magnetism in order to know, in detail, the nature of the work and problems tackled by the scientific community. Thus, AGICO has its own group of scientists who analyze instrumental problems under consideration, suggest measuring principles for new or improved instruments, develop measuring methods and software for data processing and publish scientific papers and case histories in international scientific papers. They routinely present papers on scientific symposia and conferences to illustrate the possible uses of the individual instruments to solve various geophysical and geological problems. We have gained a world-wide reputation through our results published on magnetic anisotropy (susceptibility anisotropy, high field magnetic anisotropy, remanence anisotropy).

In the early sixties, AGICO developed a Spinner Magnetometer for measuring remanent magnetization of even weakly magnetic rocks (Jelinek, 1966). Its sensitivity and accuracy put it far ahead of the competition, and subsequent developments have always made it the highest performance Spinner Magnetometer. Its sensitivity is limited only by the thermal noise of the pick-up coils. Continuous improvements in electronics, mechanical engineering and finally software engineering and interfacing took place through the sequence of instruments: versions JR-2 (Jelinek), JR-3 (Jelinek), JR-4 (Hulka-Jelinek), JR-5A/JR-5 (Pokorny-Jelinek-Suza), finally resulting in the JR-6A/JR-6 dual speed spinner magnetometers (Pokorny-Suza), with lower rotation speed enabling measurement of soft and fragile specimens while preserving the top sensitivity on higher rotation speed.

Our second most important instrument is the Kappabridge system for measuring magnetic susceptibility and anisotropy of susceptibility. Even the first version (KLY-1, Jelinek, 1973) was so sensitive and accurate that very weakly magnetic (even diamagnetic) rocks could be measured. The second version (KLY-2, Jelinek, 1980) was once the most frequently used instrument in the world to investigate the magnetic anisotropy of weakly magnetic and weakly anisotropic rocks. The third version (KLY-3S, Jelinek-Pokorny, 1997), utilizes a slowly spinning specimen, to enhance sensitivity and reduce measurement time to two minutes. The fourth version (KLY-4S/KLY-4, Pokorny-Suza-Hrouda, 2004) enables the susceptibility and its anisotropy to be measured in various weak magnetic fields. The measurement of bulk susceptibility variation with field is fully automated. The most recent version, MFK1-FA Multi-Function Kappabridge (Pokorny et al., 2005) works at three operating frequencies and enables the susceptibility and its anisotropy to be measured also in various weak magnetic fields. The bulk susceptibility measurement at three different frequencies is particularly useful in environmental magnetism studies.

The CS-3 furnace apparatus (Pokorny-Suza) has been designed to measure the temperature variation of magnetic susceptibility from the room temperature to 700 degrees centigrade, in unison with the Kappabridge. In weakly magnetic specimens the thermomagnetic curve can be resolved into paramagnetic hyperbola and complex "ferro"magnetic response curve. In this way, the contributions of paramagnetic and ferromagnetic sensu lato minerals to rock susceptibility can be assessed quantitatively. The CS-L cryostat apparatus (Pokorny-Suza-Silinger) allows measurement of the temperature variation of magnetic susceptibility at low temperatures ranging from liquid nitrogen temperature to room temperature in unison with the Kappabridge and CS-3 Furnace Apparatus.

The LDA-3 AF Demagnetizer (Sapik-Suza) demagnetizes a specimen by alternating magnetic field. The demagnetization process is microprocessor-controlled and automated. Equipped with the AMU-1 Anhysteretic Magnetizer option, it also enables a rock specimen to be magnetized anhysteretically when required.

To provide our customers with user-friendly software for measurement and for advanced data processing we develop corresponding software both for palaeomagnetism and magnetic anisotropy. See Software Support for details.

Bartosek, J. & Jelinek, V., 1961. Portable instrument for measuring magnetic susceptibility of rocks in situ (kappa-meter) (in Czech). Geol. pruzkum., 374-376. Praha.

Jelinek, V., 1966. A high sensitivity spinner magnetometer. Studia geophys. geod., 10, 58-77.

Jelinek, V., 1973. Precision A.C. bridge set for measuring magnetic susceptibility of rocks and its anisotropy. Studia geophys. geod., 17, 36-48.

Jelinek, V. & Pokorny, J., 1997. Some new concepts in technology of transformer bridges for measuring susceptibility anisotropy of rocks. Phys. Chem. Earth, 22, 179-181.

Parma, J., 1988. An automated torque meter for rapid measurement of high-field magnetic anisotropy of rocks. Phys. Earth Planet.Inter., 51, 387-389.

Pokorny, J., Suza, P. and Hrouda, F., 2004. Anisotropy of magnetic susceptibility of rocks measured in variable weak magnetic fields using the KLY-4S Kappabridge, 69-76. Magnetic Fabric: Methods and Applications, F. Martin-Hernandez, C.M. Luneburg, C. Aubourg & M. Jackson (eds), Geological Society, London, Special Publications, 238.

Chadima, M., Gunther, A., Hirt, A.M., Hrouda, F. and Siemes, H., 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), 361-380. Magnetic Fabric: Methods and Applications, F. Martin-Hernandez, C.M. Luneburg, C. Aubourg & M. Jackson (eds), Geological Society, London, Special Publications, 238.

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., 82, 390-396.

Hrouda, F., 1980. Magnetocrystalline anisotropy of rocks and massive ores: a mathematical model study and its fabric implications. J. Struct. Geol., 2, 459-462.

Hrouda, F., Stephenson, A. & Woltar, L., 1983. On the standardization of measurements of the anisotropy of magnetic susceptibility. Phys. Earth Planet. Inter., 32, 203-208.

Hrouda, F., Siemes, H., Herres, N. & Hennig-Michaeli, C., 1985. The relation between the magnetic anisotropy and the c-axis fabric in a massive hematite ore. Jour. Geophys., 56, 174-182.

Hrouda, F., 1986. The effect of quartz on the magnetic anisotropy of quartzite. Studia geophys. geod., 30, 39-45.

Hrouda, F., 1987. Mathematical model relationship between the paramagnetic anisotropy and strain in slates. Tectonophysics, 142, 323-327.

Henry, B. & Hrouda, F., 1989. Analyse de la deformation finie des roches par determination de leur anisotropie de susceptibilite magnetique. C.R. Acad. Sci. Paris, s. II, 308, 31-737.

Hrouda, F. and Schulmann, K., 1990. Conversion of magnetic susceptibility tensor into orientation tensor in some rocks. Phys. Earth Planet. Inter., 63, 71-77.

Hrouda, F. & Bartoskova, L., 1990. On the detection of weak bedding parallel strain by magnetic anisotropy: a mathematical model study. Studia Geophys. Geod., 34, 327-341.

Hrouda, F. & Jelinek, V., 1990. Resolution of ferromagnetic and paramagnetic anisotropies, using combined low-field and high-field measurements. Geophys. Jour., 103, 75-84.

Hrouda, F., 1992. Separation of a component of tectonic deformation from a complex magnetic fabric. Jour. Struct. Geol., 14, 1992, 65-71.

Hrouda, F., 1993. Theoretical models of magnetic anisotropy to strain relationship revisited. Phys. Earth Planet. Inter., 77, 237-249.

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. Geophys. J. Int., 118, 604-612.

Hrouda, F., 1994. Mathematical modelling of the behaviour of passive fabric elements (and corresponding AMS) in the transpression zone, 381-392. Textures of geological materials, H.J. Bunge, S. Siegesmund, W.Skrotzki, K. Weber (eds.), DGM Verlag Oberursel.

Hrouda, F. and Henry, B., 1996. Mathematical modelling of factors affecting the regression line method for separation of ferromagnetic AMS from total rock AMS. Acta Univ.Carol., Geologica, 40, 3-12.

Hrouda, F., Jelinek, V. and Zapletal, K., 1997. Refined technique for susceptibility resolution into ferromagnetic and paramagnetic components based on susceptibility temperature-variation measurement. Geophys. J. Int., 129, 715-719.

Hrouda, F., Hanak, J. and Terzijski, I., 1999. Pore fabrics of ceramic models investigated by magnetic anisotropy. Phys. Chem. Earth (A), 24, 607-610.

Hrouda, F. and Jezek, J., 1999. Theoretical models for the relationship between magnetic anisotropy and strain: effect of triaxial magnetic grains. Tectonophysics, 301, 183-190.