TURNOVER OF SHALLOW MARINE ECOSYSTEMS DURING THE PALEOCENE-EOCENE THERMAL MAXIMUM, SLOVENIA

The Paleocene-Eocene Thermal Maximum (PETM) event (56.3 Ma) was a period of massive carbon release into the Earth system, which corresponds to major environmental upheaval. Much work has been done documenting the PETM in the deep marine realm; however, significant questions remain about the environmental impact and ecological response in shallow waters. Studying how organisms have responded to past instances of ecological change provides a long-term perspective on the impacts of large, rapid environmental perturbations. Two mid-latitude sites on the Adriatic Carbonate Platform (Kras region, Slovenia) provide a long-term record of shallow marine faunal and environmental change from the Late Paleocene through the Early Eocene. These sites record a major negative carbon-isotope excursion at the Paleocene-Eocene transition indicating a carbon cycle perturbation similar in magnitude to excursions observed globally, and X-Ray Flourescence analysis reveals a shift in both major and minor elemental composition at this horizon as well. Two major changes in ecology also occur; there is a shift from foraminiferal shoals to an encrusting foraminiferal-microbial mound in the late Paleocene, which then transitioned to a large benthic foraminifera-dominated ecosystem prior to the Paleocene-Eocene boundary. Foraminiferal assemblages and abundances are substantially different from the Paleocene to the Eocene, and large benthic foraminifera undergo a step-wise turnover during the early Eocene. This study gives a high resolution, quantitative perspective on faunal turnover during a time of extreme climate change, and provides a potential analogue for modern ecological disturbances.