Insights into the pace and paleoceanography of early Eocene events of global warning

The hyperthermals of the early Eocene are the best examples in recent earth history of the climate systems' response to massive increases in green house gases on a scale or pace comparable to realistic scenarios of continued fossil fuel burning. In this dissertation geochemical and stable isotopic techniques are applied to deep-sea sediment cores for the purpose of constraining the chronology and character of two of these events, the Paleocene Eocene Thermal Maximum (PETM: ∼55.5Ma) and the Second Eocene Thermal Maximum (ETM2; ∼53.6 Ma). Focusing on the pace of perturbations to the marine carbonate system provides constraints on the amount and source of carbon associated with each event, ultimately to constrain climate sensitivity in a high CO 2 world.;The set of experiments presented herein first tests and refines the use of helium isotopes for reconstructing sub-orbital resolution mass accumulation rates and age models for the PETM, then pairs these methods with the more established paleoceanographic techniques to advance the characterization of subsequent smaller warming events including the ETM2. Chapter One presents a 3He based chronology for the PETM and discusses the discrepancies between it, similar work from another site and the leading alternative age model based on orbital cycle counts. Chapter Two presents additional He records from two nearby sites that bracket the first in water depth. This depth transect provides additional constraint on one of the largest sources of uncertainty in He based chronologies, variability in the extraterrestrial flux. Here the three chronologies and an unexpected signal in 4He are discussed. Chapter Three extends documentation of the ETM2 carbon isotope excursion and patterns of carbonate dissolution into the critically underrepresented Pacific basin. Bulk carbonate delta13C records are presented from three sites from Shatsky Rise in which ETM2 and subsequent minor hyperthermals are identified. Helium and benthic isotopic records from the shallowest site are also presented and their implications for the magnitude of the ETM2 CIE, warming and patterns of carbonate accumulation are discussed.