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

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Permian A-type rhyolites of the Drienok Nappe, Inner Western Carpathians, Slovakia: Tectonic setting from in-situ zircon U–Pb LA–ICP–MS dating

Published: Apr 2022

Pages: 123 - 136

DOI: https://doi.org/10.31577/GeolCarp.73.2.2

Authors: MARTIN ONDREJKA, RASTISLAV VOJTKO, MARIÁN PUTIŠ, DAVID M. CHEW, MÁRIO OLŠAVSKÝ, PAVEL UHER, ONDREJ NEMEC, FOTEINI DRAKOU, ALEXANDRA MOLNÁROVÁ, JÁN SPIŠIAK

Abstract: Two representative peraluminous A-type rhyolite samples from the Poniky area (the Drienok Nappe) in the Inner Western Carpathians (central Slovakia) were dated using the LA–ICP–MS U–Pb zircon method. These geochronological data represent the first in-situ isotopic dating study undertaken on these volcanic rocks. Oscillatory zoned zircon crystals yielded concordant Permian (Guadalupian) ages of 271.0 ± 1.5 Ma and 267.5 ± 1.6 Ma for the Poniky rhyolites, which supports their genetic link to the analogous mid-Permian (Guadalupian) rhyolites of adjacent Muráň and Vernár nappes. The Ti-in-zircon geothermometry (corrected using the activities of SiO2 and TiO2 using the rhyolite-MELTS thermodynamic software) indicate mean zircon crystallization temperatures of ~910 to 935 °C for the Poniky rhyolites. The results indicate pulses of anorogenic A-type rhyolitic magmatism were coeval with intrusions of granitic rocks associated with an intraplate extensional tectonic regime triggered by asthenospheric upwelling in the Western Carpathian region. The A-type magmatism was most likely related to the break-up of the Pangea supercontinent during the mid-Permian (~270–260 Ma).

Keywords: zircon, U–Pb LA–ICP–MS dating, rhyolite, Permian, Western Carpathians

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