A high resolution paleotemperature record across the K-Pg boundary from Seymour Island, Antarctica

TOBIN, T.; WARD, P.; KIRSCHVINK, J.; OLIVERO, E. B.; EILER, J.

Denver, USA

Congreso; 2010 GSA Denver Annual Meeting; 2010

 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.