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Geochemistry and provenance of the Upper Miocene and Pliocene sediments from the southwestern part of the Pannonian Basin System, Croatia

The Pannonian Basin System (PBS) is a system of small basins whose development started in the Early Miocene as a result of continental collision and subduction of the European Plate beneath the Apulian Plate. During the Late Miocene and Pliocene, in the south-western part of the PBS, a several km thick sequence of sandy and pelitic sediments was deposited. Previous studies have mainly dealt with the modal composition of these sediments, while there exists very little data about their geochemical characteristics. The aim of this study was to de - termine the geochemical characteristics and origin of the Upper Miocene and Pliocene sands and Upper Miocene pelitic sediments from the south-western part of the PBS. According to the content of major and trace elements these sands mostly belong to the lithoatrenite group (according to Pettijohn et al., 1972) or lithoarenite and greywacke group (according to Herron, 1988). The chemical composition of major elements indicates that the source rocks of sandy and pelitic detritus (Roser and Korsch, 1988) were mostly quartz-rich sedimentary rocks, felsitic rocks and neutral igneous rocks. Trace elements also show that the analysed sediments were mostly formed by weathering of acidic (Si-rich), or felsitic rocks. The major and trace element content according to Bhatia and Crook, (1986) and Roser and Korsch (1986) suggests that the source rocks geotectonically belong to continental islands arc and active continental margin settings. The obtained results are in accordance with the results of the provenance analysis of the same sediments based on their modal composition. Namely, according to Kovačić & Grizelj (2006) and Grizelj et al. (2007) the source rocks of clastic detritus, which filled the south-western part of the PBS in the Upper Miocene and Pliocene, were mostly older sedimentary and metamorphic rocks of a recycled orogen setting, probably the Alps and Carpathians.

geochemistry; provenance; Upper Miocene; Pliocene; Pannonian basin

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