Paleocene-Eocene transitional events in the ocean: Faunal and isotopic analyses of planktic foraminifera

The warmest period on earth during the last 70 million years occurred across the Paleocene-Eocene (P-E) transition. This climatic warming was accompanied by long-term and short-term global changes which affected atmospheric, oceanic, biotic and geologic activities. This thesis is aimed at investigating the oceanic aspects of these global changes transition using faunal and isotopic analyses of planktic foraminifera. The results indicate a long-term global change over a period of 5-7 million years characterized by warming of 4{dollar}spcirc{dollar}C in the deep ocean and high-latitude surface ocean, a negative shift of nearly 3{dollar}perthous{dollar} in carbonate {dollar}deltasp{lcub}13{rcub}{dollar}C values and a proliferation of thermophilic species into high latitudes. Coincident with this long-term global change is a rearrangement in plate boundaries and increased sea-floor hydrothermal activities. Superimposed on this long-term change is a short-term global change that occurred over less than 10 thousand years and lasted over 100-200 thousand years. This short-term change is characterized by warming of 2-4{dollar}spcirc{dollar}C in the deep ocean and high-latitude surface ocean, a negative excursion of more than 2{dollar}perthous{dollar} (global average) in carbonate {dollar}deltasp{lcub}13{rcub}{dollar}C values, a mass extinction in benthic foraminifera, a major faunal turnover in planktic foraminifera and decreased carbonate content in marine sediments. The large amplitudes of the {dollar}deltasp{lcub}13{rcub}{dollar}C shifts during both long-term and short-term global changes suggest increased transport of organic carbon from sedimentary reservoirs into the atmosphere and ocean. Such a transport is currently considered the cause of the changing climate and ocean chemistry during the long-term change. However, it is not clear what mechanisms resulted in such a rapid release of sedimentary organic carbon during the short-term global change, since the timing and amplitude of the {dollar}deltasp{lcub}13{rcub}{dollar}C excursion suggests that the release occurred at a rate comparable to fossil fuel burning today.