Lénárt R. & Hók J., 2010: Shear deformation analysis in granite of the Tribeč Mts. (Western Carpathians). Acta Geologica Slovaca, 2, 2, 141–147. (in Slovak with English summary)

Analýza strižnej deformácie v granitoidoch zoborskej časti Tribeča (Západné Karpaty)

Shear deformation analysis in granite of the Tribeč Mts. (Western Carpathians)

Rudolf Lénárt & Jozef Hók

Katedra geológie a paleontológie, Prírodovedecká fakulta, Univerzita Komenského v Bratislave, Mlynská dolina G, 842 15 Bratislava; lenart@fns.uniba.sk, hok@fns.uniba.sk

Abstract

The mylonitised granitic rocks were object of the study in the Zobor part of the Tribeč Mts. They were metamorphosed under greenschist facies conditions during simple shear deformation. The shear (mylonite) zones are oriented in the NE–SW direction in the investigated area. Prevailing of the shear zones has sinistral sense of displacement. The origin of the sinistral shear zones is connected with compression oriented in the N–S direction during the Latest Cretaceous to Palaeocene. The dextral shear zones together with folds observed in the Lower Triassic sediments of the Lúžna Fm. were generated under the WNW–ESE oriented compression. The origin of the dextral shear zones is interpreted as a consequence of thrusting of the Central Western Carpathian tectonic units (Veporic and Fatric units) during the Late Cretaceous (Cenomanian). The sinistral shear zones were most probably superposed on dextral shear zones because of reorientation of the stress field to the N–S direction during the Latest Cretaceous–Earliest Palaeogene.

Key words: Western Carpathians, Tribeč Mts., granite, shear zones, mylonite

Manuscript received: 2010-04-29

Revised version accepted: 2010-09-17