Orthogneisses and metapelites from a polyphase tectonic zone - mesostructural versus microstructural evidence: an example from the Czerniawa Zdrój section (Izera-Karkonosze Block, West Sudetes)

Abstract

Within the gneisses of the northern part of the Izera–Karkonosze Block (West Sudetes), there are 4 belts of schistose rocks. The Stara Kamienica schist belt in the Czerniawa section consists of a sequence of orthogneisses deformed to various degree, occurring concordantly with metapelitic mica schists. Structural analysis of these rocks, including quartz c-axis analysis, allows four stages of deformation, common for both lithologies to be recognized. The quartz c-axis microfabrics are often incompatible with other elements of the structural record, which is interpreted as having resulted from multiple overprinting of older microfabrics by younger ones in a heterogeneous deformation regime. This heterogeneity concerns the geometry of the deformation as well as the mechanisms, which included subgrain-rotation recrystallization, grain-boundary migration, microfracturing and pressure-solution processes.