COG3

Molecular and isotopic indicators of paleoenvironmental change in the Western U.S.

Abstract:

Terrestrial sediments provide important records of continental temperature, hydrology and isotopes of precipitation, yet are these are often readily interpreted in terms of either climatic or orographic effects. As a result, linking models of past global climatic with terrestrial temperature information is hampered by separating topographic and climatic effects in the paleoenvironmental record. Organic molecular proxies provide one tool for examining long-term terrestrial environmental change because they serve as a record of the isotopic composition of ancient precipitation, vegetation, water stress, and temperature. This talk will examine differences in C and H isotope discrimination in modern and ancient plant waxes that span a range of environmental conditions in order to elucidate the impact of ecosystem-level differences on C and H isotope discrimination. These relationships are applied to Cenozoic biomarker isotope records from western North America to provide constraints on climatic and tectonic conditions in this region during the Cenozoic.