Pages: 274 - 287
Abstract: U–Pb dating of magmatic zircons from the Permian basaltic metaandesites/metabasalts of the Tribeč Mts. yielded the Concordia ages of 263.1±2.6 Ma, which correspond to the Guadalupian Epoch in the time span of the uppermost Wordian/Capitanian Stages. These magmatic zircon ages clearly document the timing of the Mid-Permian lithospheric extension in the internal zone of the Variscan fragments in the Western Carpathians. The studied volcanic rocks with the associated metasediments belong to the Veporic Unit that overthrusts the Tatric Unit. The considered sequence was correlated with the Northern Veporic Permian rocks from the Čierťaž Mts. From the geochemical point of view, the studied volcanic rocks have a calc-alkaline magmatic trend with an affinity to continental within-plate tectonic setting, linked to the post-orogenic lithospheric extension. The detrital zircon population, obtained from the associated arkosic metagreywackes, displays mainly Tournaisian and Ediacaran zircon ages in the range of 342–367 and 546–631 Ma, respectively. Only a small number of Cambrian/Ordovician (499–466 Ma), Tonian (720–1000 Ma) and Paleoproterozoic/Neoarchean (~1.9 Ga and ~2.5 Ga) zircon ages were determined. The similar association of zircon ages was found within the xenocrystic cores in the studied volcanic rocks. The presented detrital and xenocrystic zircon ages specify the provenance of the Tribeč Permian deposits from the Western Carpathian Crystalline Basement crust, characteristic of derivation from the Variscan magmatic rocks and reworked fragments of Cadomian crust.
Keywords: SHRIMP zircon dating, Permian volcanism, geochemistry, provenance, Central Western CarpathiansDownload PDF document