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Events of ductile and brittle deformations and paleomagnetic rotations within a few million years interval in the Pohorje area, Slovenia

Fodor, László and Márton, Emő and Vrabec, Marko and Jelen, Bodomir and Koroknai, Balázs and Rifelj, Helena and Vrabec, Mirjam (2014) Events of ductile and brittle deformations and paleomagnetic rotations within a few million years interval in the Pohorje area, Slovenia. In: 9th Environmental, Sedimentary & Structural Evolution of the Western Carpathians, 5-7 Nov 2014, Smolenice, Slovakia.

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Abstract

We reconstructed the deformation history of the Pohorje pluton, related subvolcanic rocks and surrounding sediments in NE Slovenia. We used classical field structural measurements, microtectonic observations in thin sections, and various approaches of paleomagnetism. In particular, we compared the main directions of deformation and the main axis of the anisotropy of magnetic susceptibility (AMS). We extended and reinterpreted our existing data base (Márton et al., 2004). The granodioritic-tonalitic Pohorje pluton suffered ductile deformation in the greenschist-facies, which is recorded in both AMS and structural microfabric characteristics. The D1 deformation shows varying styles: extensional in the southern (S) and strike-slip type in the northern part (N) of the pluton. Sub-horizontal (S) and steep foliation (N) is well developed whereas ENE–WSW (S) and SSE–NNW (N) lineation are recorded by stretched minerals and K1 AMS axis (Fig. 1). This deformation occurred just after intrusion at 18.6 Ma, during the imminent cooling of the plutonic rocks (Fodor et al. 2008). After this event, the pluton underwent ca. 70° clockwise rotation, which predates the deposition of Karpatian (17.3 Ma) sediments. During the CW rotation, and slightly after, at ca. 18-17 Ma, the pluton was intruded by diverse, mostly andesitic and aplitic dykes. The AMS indicates minor ca. E–W directed extension, which is sub-perpendicular to the dykes themselves. At the same time, the Karpatian sediments suffered early deformation while they were still in horizontal position. NE–SW or E–W extension was recorded by AMS, and also by pre-tilt normal faults associated with macroscopically ductile fault-related folding. Finally, the last event D3 of ca. 17-15 Ma could be the intrusion of subvolcanic dacitic dykes which show very slight magnetic anisotropy corresponding to dyke emplacement. Later it was followed by 35° counterclockwise rotation.

Item Type: Conference or Workshop Item (Lecture)
Subjects: Q Science / természettudomány > QE Geology / földtudományok
Q Science / természettudomány > QE Geology / földtudományok > QE01 Geophysics / geofizika
Q Science / természettudomány > QE Geology / földtudományok > QE03 Geodynamics / geodinamika
Depositing User: Emő Márton
Date Deposited: 19 Jan 2015 10:55
Last Modified: 19 Jan 2015 10:55
URI: http://real.mtak.hu/id/eprint/20627

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