REAL

Paleoweathering conditions of Upper Carboniferous siliciclastic rocks of SW Hungary

Varga, Andrea and Raucsik, Béla and Hartyáni, Zsuzsanna and Szakmány, György (2007) Paleoweathering conditions of Upper Carboniferous siliciclastic rocks of SW Hungary. Central European Geology, 50 (1). pp. 3-18. ISSN 1788-2281

[img]
Preview
Text
ceugeol.50.2007.1.1.pdf

Download (885kB) | Preview

Abstract

Abstract The clay mineralogical and chemical compositions of Upper Carboniferous siliciclastic rocks from the western flank of the Villány Mountains (Téseny Sandstone Formation) have been investigated to determine paleoweathering conditions, as well as to appraise the influence of the post-depositional processes upon source rock signature. The clay-mineral assemblage of the samples consists predominantly of illite±muscovite, suggesting a potassium metasomatism in the Téseny clastics. Therefore the use of the Chemical Index of Alteration (CIA), which provides a consistent quantitative framework for examining weathering, leads to erroneous conclusions without correction for K-metasomatism. When considered in Al2O3-CaO* + Na2O-K2O (A-CN-K) compositional space, orthogneiss and igneous rock clasts selected from the Téseny conglomerate reflect two different weathering trends; one (including orthogneiss, quartz diorite, and andesite samples) shows an ideal trend observed for granodioritic rocks, and the other (including aplite, rhyodacite, and rhyolite samples) follows a trend from a slightly more K-feldspar-rich fresh rock composition than that of average granite. Intermediate to intense chemical weathering of the source areas is indicated by premetasomatized CIA values of 77–84 for the samples from borehole Siklósbodony-1, suggesting that these rocks have gained about 6–7% K2O (in A-CN-K space) during metasomatism.

Item Type: Article
Subjects: Q Science / természettudomány > QE Geology / földtudományok
Depositing User: xBarbara xBodnár
Date Deposited: 13 Jun 2017 06:57
Last Modified: 13 Jun 2017 06:57
URI: http://real.mtak.hu/id/eprint/54785

Actions (login required)

Edit Item Edit Item