THE ONSET OF THE ICEHOUSE: A GLIMPSE OF THE EOCENE-OLIGOCENE TRANSITION IN PRYDZ BAY, ANTARCTICA

The Eocene-Oligocene transition marked a profound shift in the Earth’s climate, as the global greenhouse of the early Cenozoic gave way to icehouse conditions, or a climatic regime influenced by the waxing and waning of glacial ice. Antarctica was dramatically altered during this time; its formerly cool temperate ecosystems nearly obliterated by the first major episode of continental glaciation. A record of this transition appears to be partly preserved in approximately half a kilometer of sediments recovered from three cores (at ODP sites 739, 742, and 1166) bored in the continental margin at Prydz Bay, an embayment of the East Antarctic coast. Until recently, these cores were never completely described with common nomenclature and analysis. This study re-evaluated these cores under a unified regime, using a laser particle sizer to generate grain size distribution profiles for 255 samples collected from the combined sediment column. Additional analysis of select samples was performed with a scanning electron microscope to classify grain textures, providing additional information on the potential environmental conditions sediments were previously subjected to. It is believed this analysis affords a very detailed account of what the depositional response to ice growth was during the Eocene-Oligocene at Prydz Bay. In turn, this offers new information relating to the glacial and topographic/bathymetric dynamics of the region, which has implications for both ice and climate modeling.