STABLE OXYGEN AND CARBON ISOTOPE PROFILES OF HIGH-LATITUDE LATE CRETACEOUS BIVALVES FROM SEYMOUR ISLAND, ANTARCTICA

Recent work suggests that the Chicxulub bolide impact was not the only significant mechanism driving the Cretaceous-Paleogene (K/Pg) mass extinction event (~65.5 Ma) and that there must have been several other mechanisms including climate change which also contributed to this event. The sequence, nature and magnitude of climate change approaching the Cretaceous-Paleogene is still poorly constrained. High latitude locations are of special interest because they are more sensitive to climate change. Well-preserved and expanded sedimentary sequences exposed in the Lopez de Bertodano Formation of Seymour Island, Antarctica provide an excellent opportunity to study high-latitude marine paleotemperature records of the Late Cretaceous. Here, we investigate seasonality preserved by carbon and oxygen isotope ratios in the shells of Maastrichtian-aged bivalves of the genera Eselaevitrigonia and Cucullaea. We calculate sea-surface temperatures using oxygen stable isotope ratios, under the assumption that d18O of the ambient seawater is -1.2‰ (VSMOW) for an ice-free world. Our preliminary results indicate an up-section increase in temperature which agrees with observations in the literature. We also explore the possibility that this trend is a consequence of diagenesis, vital effects, or changes in the paleobathymetric preferences of the organisms studied.