Geochemical record of Late Devonian to Early Carboniferous events, Palaeozoic of Graz, Eastern Alps, Austria
Published:January 01, 2013
Ana-Voica Bojar, Franz Neubauer, Christian Koeberl, 2013. "Geochemical record of Late Devonian to Early Carboniferous events, Palaeozoic of Graz, Eastern Alps, Austria", Palaeozoic Climate Cycles: Their Evolutionary and Sedimentological Impact, A. Gąsiewicz, M. Słowakiewicz
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The late Famennian mass extinction has been associated with a worldwide anoxic event evidenced at many sites by the accumulation of organic-rich shales starting prior to the Devonian–Carboniferous (D/C) boundary. Environmental reconstructions are hampered by the fact that only a few D/C boundary sections exist in carbonate facies. One of these is the Palaeozoic Steinberg section, Eastern Alps, Austria. Based on detailed geochemical investigations and correlation with previously investigated sections, we propose a succession of events from the late Famennian to the Tournaisian. Both the low total rare earth element (REE) contents and the normalized REE distribution patterns indicate low terrigenous input from the praesulcata Zone to the typicus Zone. The δ13C, δ18O, δ34S and total organic content (TOC) show a shift towards higher values, which correlates well with the late Famennian isotopic trends that are related to a period of active ocean circulation, cooling and increased productivity. Two isotopic shifts are present in the section: the older isotopic shift of the δ13C values is situated at the level of the Lower to Middle praesulcata Zone, while the younger one is found at the level of the Upper praesulcata Zone. In the sulcata Zone, a sharp decrease in δ18O values and a shift in the Ce anomaly follow. Concomitantly, a drop in the δ13C and δ34S values, highly variable TOC values, and the main and secondary element concentrations are interpreted to be related to a drop in primary productivity, with the recovery continuing in the crenulata Zone. In this context, the variations towards lower CaO, Sr, Rb and Ba values probably correlate with biomass variations and a transition from cooler towards warmer conditions.
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Palaeozoic Climate Cycles: Their Evolutionary and Sedimentological Impact
This volume presents results of a variety of case studies documenting the Late Palaeozoic climate changes and cyclicity of deposition. The collected papers cover many aspects related to palaeoenvironmental analysis with sedimentological, stratigraphic, palaeobiological, geochemical, and palaeomagnetic studies of the fossil record around the Late Palaeozoic Ice Age and soon after. They span a stratigraphic interval from Carboniferous to Permian–Triassic transition around the world.
This book comprising results for a range of disciplines, is a valuable source for not only researchers who are actively working on specific aspects of the Late Palaeozoic and looking for an up-to-date reference on this inhospitable time in the Earth’s history. It is also of interest to climate modellers and the wider scientific community with an interest in the latest research on the decline of the Palaeozoic World.