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Geologica Carpathica, 2013, vol. 64, no. 2
Kinematically unrelated C–S fabrics: an example of extensional shear band cleavage from the Veporic Unit (Western Carpathians)
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
Pages:
103 - 116
Published online:
0. 4. 2013