Sedimentology and isotope geochemistry of Carnian deep-water marl/limestone deposits from the Sicani Mountains, Sicily: Environmental implications and evidence for a planktonic source of lime mud

摘要: Abstract The upper Triassic Halobia-bearing marl/limestone deposits from the Sicani Mountains (Sicily) record sedimentary evolution of Sicanian Basin through middle and late Carnian time. Dark marls interbedded grey calcilutites Julian age are characterized by abundant pyrite, sparse bioturbation negative carbonate carbon δ13C values. They accumulated in a basin with dominantly anoxic to dysaerobic bottom waters. Lower Tuvalian dark-grey pyritic calcilutites, which contain minerals relatively high Mn contents widely fluctuating signatures, were deposited under conditions. Middle cherty limestones show intense nearly invariable positive values (around 2‰ for calcite). form thick monotonous succession deeper more oxygenated basin. preserve some calcareous nannoplanktonic forms. nannofossils, varying size 7 32 μm, significantly pointing notable role nannoplankton as source mud deep-water basins southern Tethys during