Changes in biological productivity in the lower part of the PCS sediment core (Lower Pleistocene, Calabria, Southern Italy)

Changes in primary biological productivity within individual ocean basins and seas reflect the natural variability in climate, terrigenous yield from the basin margin, sea level, circulation and geochemical composition of the water column. The number of active processes is especially high in shalfal settings, where they form a complex interplay that can hardly be disentangled. The role of each potential factor can be grossly estimated by reconstructing a detailed foraminiferal δ18O and δ13C record, to be compared with other proxies such as physical stratigraphy and the study of fossil faunas. In this respect, we attempted assessing the changes in biological productivity in the Lower Pleistocene stratigraphic record of the Crosia sedimentary basin (Calabria, Southern Italy). The studied interval belongs to a ca. 90-m long sedimentary core (PCS core) drilled inland of the Ionian Sea in 2010. I have reconstructed a stable isotopic record for the benthic foraminiferal species Uvigerina Peregrina, which possibly offers the most reliable biotic archive of the paleoclimatic and paleoenvironmental conditions at the seafloor. Through the analysis of carbon and oxygen isotope curves, it is found that there are two peaks of productivity in the record of the lower part of PCS core, one is the highest value at -59m, and the other is the lowest value at -74m. At the same time, productivity is reduced due to the decreased bottom water ventilation when the sapropel is formed. The decrease of δ13C in sand layer is due to the input of terrestrial organic matter to the ocean.