International Geological Journal - Official Journal of the Carpathian-Balkan Geological Association

Kinematically unrelated C–S fabrics: an example of extensional shear band cleavage from the Veporic Unit (Western Carpathians)

Pages: 103 - 116

Authors: ZITA BUKOVSKA, PETR JERABEK, ONDREJ LEXA, JIRI KONOPASEK, MARIAN JANAK, JAN KOSLER

Abstract: Discontinuous and kinematically unrelated C–S fabrics have been recognized along the contact between the Gemeric and Veporic Units in the Western Carpathians. The formation of S and C fabrics within orthogneiss, quartzite and chloritoid-kyanite schist of the Veporic Unit is associated with Cretaceous syn-burial orogen-parallel flow and subsequent exhumational unroofing. The formation of the two fabrics characterized by distinct quartz deformation microstructure and metamorphic assemblage is separated by an inter-tectonic growth of transversal chloritoid-, kyanite-, ± monazite-bearing assemblage. The monazite U-Th-Pb concordia age of 97±4 Ma was obtained by the laser ablation ICP–MS dating method. The age of this inter-tectonic metamorphic stage together with existing 40Ar/39Ar ages on exhumation of the Veporic Unit indicate that despite the similar appearance to shear bands or C–S mylonites there is a time span of at least 10 Myr between the formation of homogeneous S fabrics and superposed discrete C fabrics in the studied rocks.

Keywords: Central Western Carpathians, Veporic Unit, structural geology, monazite dating, quartz deformation microstructure, shear band cleavage, discontinuous C-S fabrics

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