A HIGH RESOLUTION PALEOTEMPERATURE RECORD ACROSS THE K-PG BOUNDARY FROM SEYMOUR ISLAND, ANTARCTICA

Seymour Island, in the James Ross Basin on the West Antarctic Peninsula, is the southernmost marine K-T boundary section in the world, and consequently provides valuable information on the latitudinal variability on the impact of the K-T event. Seymour Island has moved less than three degrees of latitude since deposition and has undergone minimal deformation (structural tilt ~5°) and diagenesis (most fossils preserve original aragonite). The Lopez de Bertodano formation is comprised of immature mud to sand deposited in a back-arc setting on the middle to inner shelf during the upper Maastrichtian and Danian. The high level of preservation allows for stable isotope analysis of the predominantly molluscan shell material. Preliminary δ¹⁸O data from aragonitic (confirmed by XRD analysis) shells suggest that temperatures were considerably higher during the Maastrichtian and Danian than today (~10°C versus near 0°C), assuming minimal diagenetic alteration and a seawater δ¹⁸O composition of -1.0‰. These results are in broad agreement with previous studies and with preliminary results using the ‘clumped isotope in carbonate’ paleothermometer, which indicate seawater temperatures of ~12°C or lower. These previous studies have provided low temporal resolution temperature estimates throughout the end of the Cretaceous. A high resolution temporal record and preliminary clumped isotope results will be presented at the conference. A comparison with known paleodiversity and paleoecological records will be made.