BIBLIOS

Document type
Journal articles

Document subtype
Full paper

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

Participants in the publication
V. K. Kusbach (Author)
M. Machek (Author)
Z. Roxerová (Author)
M. Racek (Author)
P. F. Silva (Author)
Dep. Engenharia Geográfica, Geofísica e Energia
IDL

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


Institution
FACULDADE DE CIÊNCIAS DA UNIVERSIDADE DE LISBOA

Where published
Scientific Reports

Publication Identifiers
ISSN - 2045-2322

Publisher
Springer Science and Business Media LLC


Document Identifiers
DOI - https://doi.org/10.1038/s41598-019-53794-y
URL - http://dx.doi.org/10.1038/s41598-019-53794-y