Localization effect on AMS fabric revealed by microstructural evidence across small-scale shear zone in marble

0521627 - GFÚ 2020 RIV GB eng J - Článek v odborném periodiku
Kusbach, Vladimír - Machek, Matěj - Roxerová, Zuzana - Racek, M. - Silva, P. F.
Localization effect on AMS fabric revealed by microstructural evidence across small-scale shear zone in marble.
Scientific Reports. Roč. 9, č. 1 (2019), č. článku 17483. ISSN 2045-2322. E-ISSN 2045-2322
Grant CEP: GA ČR(CZ) GJ16-25486Y
Institucionální podpora: RVO:67985530
Klíčová slova: magnetic anisotropy * magnetic fabric * magnetic foliation
Obor OECD: Geology
Impakt faktor: 3.998, rok: 2019
Způsob publikování: Open access
https://www.nature.com/articles/s41598-019-53794-y

Anisotropy of magnetic susceptibility (AMS) is regularly applied as a tool to infer structural analysis of deformation and flow in rocks, particularly, with low anisotropy. AMS integrates the magnetic signature of crystallographic and shape preferred orientation of all mineral grains present in the rock microstructure. Those preferred orientations result from multiple processes affecting the rock during its evolution, therefore the desirable AMS-strain relationship is not straightforward. Here we show that due to localization of deformation, AMS is indirectly dependent on the magnitude and character of deformation. In order to decipher the AMS-strain relationship, AMS studies should be accompanied by microstructural analyses combined with numerical modelling of magnetic fabric. A small-scale shear zone produced by single deformation event was studied. The resultant AMS fabric is inverse due to the presence of Fe-dolomite and controlled by calcite and dolomite crystallographic preferred orientations. The localized deformation resulted in the angular deviation between macroscopic and magnetic fabric in the shear zone, systematically increasing with increasing strain. This is a result of the presence of microstructural subfabrics of coarse porphyroclasts and fine-grained recrystallized matrix produced by localization.The localization of deformation is a multiscale and widespread process that should be considered whenever interpreting AMS in deformed rocks and regions.
Trvalý link: http://hdl.handle.net/11104/0306223