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

DEFORMATION PHASES IN THE SELECTED SHEAR ZONES WITHIN THE TATRA MOUNTAINS GRANITOID CORE

Pages: 17 - 28

Authors: EDYTA JUREWICZ, BOGUSLAW BAGINSKI

Abstract: The paper presents the complex geological structure and microstructure of four selected polydeformed shear zones within the granitoid core of the High Tatra Mountains. Sequences of deformation and mineralization were determined for each zone. In order to determine the deformation conditions, petrotectonic analysis and the chlorite geothermometer were applied. The obtained data were correlated with earlier published fluid inclusions investigations. Next, the results were supported by petrotectonic and structural analyses, and on the basis of the whole set of data three groups of structures were distinguished: 1 — pre-Alpine (connected with late Variscan extension or Early Jurassic rifting, brittle-plastic in character); 2 — Alpine (formed during the Late Cretaceous thrusting, marked by the presence of flat-dipping slickensided faults); 3 — late Tertiary (linked with the uplift of the Tatra massif and the accompanying extension and sinistral oblique-normal-slip faults). On the basis of the pressure 1.45–1.70 kba (145–170 MPa) and temperatures (212–254 °C) estimated from fluid inclusion analysis, as well as temperatures range of 205–250 °C obtained from the Cathelineau geothermometer, the depth of the granitoid massif position during the Late Cretaceous Alpine thrust folding was determined at 6–7 km and the geothermal gradient at ca. 30 °C.

Keywords: Western Carpathians, High Tatra Mountains, tectonic evolution, shear zones, granitoid rocks, cataclasites, mylonites

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