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

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The petrology and geochronology of the gabbro-dioritoid rocks from Veľké Železné (Nízke Tatry Mts., Western Carpathians)

Published: Feb 2024

Pages: 3 - 20

DOI: https://doi.org/10.31577/GeolCarp.2024.02

Authors: JÁN SPIŠIAK, MILAN KOHÚT, JURAJ BUTEK, ŠTEFAN FERENC, VIERA ŠIMONOVÁ, RICHARD KOPÁČIK, DAVID CHEW

Abstract: The gabbro-dioritoid rocks from Veľké Železné (Nízke Tatry Mts., Western Carpathians, Slovakia) were recently studied in order to better understand the age, origin, and evolution of the basic/intermediate magmas associated with Variscan granitic rocks. Their genesis was investigated from the points of view of petrology, whole-rock geochemistry (including Sr, Nd, and Pb isotopic characteristics), as well as U–Th–Pb zircon and apatite dating. The Famennian magmatic crystallization age of ca. 360 Ma (determined from zircon: 362.4 ± 2.9 Ma and apatite: 358.4 ± 2.8 Ma) is older than the Tournaisian–Visean ages for granite intrusions in the Tatric Unit. Geochemically, the studied rocks have an affinity to arc-related basalts, consisting of a metaluminous, magnesian, and high-potassium calc-alkaline character. Isotope data (i.e., (87Sr/86Sr)360 = 0.7035−0.7044 and εNd360 = +1.4 to +1.6) demonstrate that these gabbro-dioritoids were formed from the mantle-influenced, lower crustal and/or sub-continental lithospheric mantle (SCLM) sources, whereas the unsystematic increase of Pb isotope ratios indicate either the melting of an ancient Enriched mantle-II (EM-II) reservoir or the upper crustal assimilation and/or local fluid alteration. The data presented in this paper favour the origin of the studied gabbro-dioritoids at a continental arc, although we cannot rule out their genesis as a result of the subsequent slab break-off.

Keywords: gabbro-dioritoids, petrology, geochemistry, U–Th–Pb zircon & apatite dating, Nízke Tatry Mts., Western Carpathians

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