Relationships between magnetic and structural fabrics revealed by Variscan basement rocks subjected to heterogeneous deformation—a case study from the Kłodzko Metamorphic Complex, Central Sudetes, Poland

Abstract

AbstractThe Kłodzko Metamorphic Complex comprises a number of thrust units, consisting of meta-igneous and metasedimentary rocks of the Variscan basement of the Sudetes, NE Bohemian Massif. The thrust sheet stack rests upon unmetamorphosed Nowa Ruda ophiolite and is unconformably overlain by Frasnian-Fammenian sediments. The studied rocks underwent six deformation events, scattered in time between the Middle Devonian and Late Carboniferous. The multiphase deformation produced a steep foliation that consistently trends WNW-ESE and a mineral lineation plunging to the ESE at a shallow to moderate angle. The results of the AMS study show that, despite the complex structural evolution, all the studied rocks bear a similar magnetic fabric mirroring the principal structural directions. This relationship between magnetic and structural fabrics is apparent in all tectonic units irrespective of the considerable variations in strain rate and metamorphic grade. This suggests a rather low dependence of magnetic anisotropy on the changing conditions and intensity of deformation.