Dr. Kyger C Lohmann, University of Michigan

Stable isotope geochemistry has long been employed as a primary proxy for deciphering variations in global climate through an analysis of carbonate shells of marine organisms. However, such an approach has been hampered by the relatively poor temporal resolution provided by pelagic ocean sediment sequences, as well as the inability to dissociate the affects imparted by changes in ocean water composition from changes in temperature. By combining isotopic measurements with elemental proxies of temperature and salinity, it is now possible to uniquely reconstruct the nature of past changes in temperature, salinity and ocean water compositions. This presentation will explore the utility of high-resolution analysis of the growth banding structure of mollusks to reconstruct changes in sea surface temperatures, on annual to seasonal time scales, through critical intervals of climate change. Examples include studies of the Holocene of coastal Antarctica, the Pleistocene of the Pacific Coast of Oregon, the Cretaceous-Paleogene (K/P) of Seymour Island. In addition, these data will be contrasted with high resolution bulk sample and foraminifer data from K/P pelagic sediments recovered during Leg 208 to provide insights into the variability of how climate is manifested in coeval pelagic and marine shelf settings.

Dr. Lohmann has participated on two ODP Legs as a shipboard sedimentologist. These include Leg 159, Côte d'Ivoire-Ghana Transform Margin, Eastern Equatorial Atlantic in 1995 and Leg 208, Early Cenozoic Extreme Climates: The Walvis Ridge Transect in 2003.