Geochemistry of fine-grained sediments of the upper Cretaceous to Paleogene Gosau Group (Austria, Slovakia): Implications for paleoenvironmental and provenance studies

Bulk rock geochemistry of 169 fine-grained sediment samples of the upper Cretaceous to Paleogene Gosau Group (Northern Calcareous Alps, Austria and Slovakia) from borehole and outcrop localities was performed to separate non-marine and marine deposits. Geochemical characteristics of different Gosau depositional systems, basins and sediment provenance using major-, trace-, and rare earth elements were also investigated. Geochemical proxies such as boron concentrations were tested for seeking the possibilities of paleosalinity indicators. Due to the fact that several pelagic sections are represented by extremely low boron contents, B/Al* ratios are recognized as more robust and differentiate reliably between marine (mean: 160 ± 34) and non-marine (mean: 133 ± 33) samples. Using statistical factor analysis, hemipelagic to pelagic samples from the Gießhübl Syncline and Slovakian equivalents can be differentiated from marginal-marine to non-marine samples from the Grünbach and Glinzendorf Syncline related to terrigenous (SiO2, Al2O3, K2O, Th, Rb, Zr and others) and pelagic indicative elements (CaO, Sr, TOT/C and B/Al*). A clear indication for ophiolitic provenance is traced by high amounts of chromium and nickel. Only non-marine successions of the Glinzendorf Syncline show higher Cr and Ni concentrations (up to 250 and 400 ppm, respectively) and enriched Cr/V and Y/Ni ratios trending to an ultramafic source.

Figure optionsDownload as PowerPoint slideHighlights
► Comparison of geochemical proxies for reconstruction of paleodepositional conditions.
► Boron normalized with aluminium as a tool to determine paleosalinity.
► High chromium and nickel concentrations suggest ophiolitic source.
► Factor analysis as a tool to distinguish sediments from different sources.