Institute of Geophysics of the CAS, v. v. i.

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Anisotropy of magnetic susceptibility studies

Anisotropy of magnetic susceptibility studies

The Earth Sciences use information on the internal fabrics of rocks in order to understand their deformation history, magmatic or sedimentary flow direction and processes of sedimentation. A fundamental technique to measure the internal rock structure is the anisotropy of magnetic susceptibility (AMS), because of the easiness and quickness of measurement and high sensitivity. The AMS measurement becomes one of the most popular structural techniques to determine anisotropic fabric in rocks with lack of macroscopically visible structures.

Our studies aim at understanding the AMS formation and its textural response in rocks and magma under deformation and processes of chemical and mineral changes of the rock system. In our work we combine the detailed study of AMS and other magnetic properties with microstructural analysis, crystal preferred orientation (CPO) estimation and other rock properties (eg. chemical composition and porosity characteristics). The research is based on natural examples as well as experimental studies. In our group we currently concentrate on three research directions in the field of AMS development in rocks:

1) AMS relevance and response to development of complex fabrics in crystal mush

  • - Flow fabrics in dacite lava flows on slopes of Three Sisters volcanoes in Oregon (USA)
  • - Intrusion fabrics in Castle Crags and Caribou Mountain plutons in Klamath Mountains, California (USA)
  • - Analysis of fabrics of the chilled margin of a thick dolerite dyke (Foum Zguid dyke, Southern Morocco)

2) AMS development under deformation gradient

3) AMS response to chemical and mineral changes in rocks

  • - Effects of alteration processes (alkali feldspathization and greisenization) on magnetic and porosity properties in granites of the Vysoký Kámen stock (the Krudum granite body, Czech Republic
  • - Paramagnetic/Ferrimagnetic AMS as result of topotactic relations between ultramafic minerals and product of their serpentinization