Geochemistry of Sarmatian volcanic rocks in the Tokaj Mts (NE Hungary) and their relationship to hydrothermal mineralization

Kiss, Péter and Gméling, Katalin and Molnár, Ferenc and Pécskay, Zoltán (2010) Geochemistry of Sarmatian volcanic rocks in the Tokaj Mts (NE Hungary) and their relationship to hydrothermal mineralization. Central European Geology, 53 (4). pp. 377-403. ISSN 1788-2281


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Abstract In the Tokaj Mts (NE Hungary), which is a part of the Inner Carpathian Volcanic Arc, large amounts of intermediate-acidic calc-alkaline volcanic rocks accumulated in a N-S oriented graben-like structure during the Badenian-Sarmatian-Pannonian period, in relation with the closure of the Alpine Tethys (Penninic) ocean. Although previous research on volcanism and related hydrothermal processes produced a huge number of K/Ar age data no systematic petrochemical database has been available up to now from the Tokaj Mts. In this study we publish new results of geochemical analyses completed on systematically collected basaltic, andesitic, dacitic and rhyolitic rocks, and of the spatialtemporal evaluation of petrochemical signatures, with special reference to origin of magmatism and relationships of rhyolite to hydrothermal mineralization. In the southern Tokaj Mts rhyolite contains K-feldspar phenocrysts, while this phenomenon is absent in the rhyolite from the northern areas of the mountains. In accordance with this, significant potassium enrichment occurs in the south (whole rock K2O content varies between 4.35 and 5.61 wt%), whereas rhyolite from the northern Tokaj Mts is less enriched in potassium (K2O content is from 3.28 to 5.1 wt%). The most significant difference between the northern and southern dacite is the age of their formation. They were formed at the same time as rhyolite and andesite (between 13.4 and 11 Ma) in the northern Tokaj Mts, while they are much younger (10.57–10.1 Ma) in the southern Tokaj Mts, where they post-date hydrothermal activity. The boron content (10.1–52.12 µg/g) and the patterns of other trace elements of the volcanic rocks show typical subduction-related features; however, direct influx of subduction-related fluids during magma generation can be excluded. A more plausible explanation for the magma genesis is decompression melting of a previously metasomatized mantle, enriched with subduction-related components. Additionally, the unmineralized northern rhyolite samples contain much less Cl (usually below 0.2 wt%) than the high-K rhyolite in the southern part of the Tokaj Mts (usually more than 0.2 wt%), which correlates with the presence/absence of spatially and temporally related epithermal mineralization in these areas.

Item Type: Article
Subjects: Q Science / természettudomány > QE Geology / földtudományok
Depositing User: xBarbara xBodnár
Date Deposited: 20 Jun 2017 07:11
Last Modified: 04 Apr 2023 12:54

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