IODP expedition 318: From greenhouse to icehouse at the Wilkes Land Antarctic margin

Abstract

Integrated Ocean Drilling Program (IODP) Expedition 318, Wilkes Land Glacial History, drilled a transect of sites across the Wilkes Land margin of Antarctica to provide a long-term record of the sedimentary archives of Cenozoic Antarctic glaciation and its intimate relationships with global climatic and oceanographic change. The Wilkes Land drilling program was undertaken to constrain the age, nature, and paleoenvironment of the previously only seismically inferred glacial sequences. The expedition (January-March 2010) recovered -2000 meters of high-quality middle Eocene-Holocene sediments from water depths between 400 m and 4000 m at four sites on the Wilkes Land rise (U1355, U1356, U1359, and U1361) and three sites on the Wilkes Land shelf (U1357, U1358, and U1360). These records span -53 million years of Antarctic history, and the various seismic units (WL-S4-WL-S9) have been successfully dated. The cores reveal the history of the Wilkes Land Antarctic margin from an ice-free "greenhouse" Antarctica, to the first cooling, to the onset and erosional consequences of the first glaciation and the subsequent dynamics of the waxing and waning ice sheets, all the way to thick, unprecedented "tree ring style" records with seasonal resolution of the last deglaciation that began -10, 000 y ago. The cores also reveal details of the tectonic history of the Australo-Antarctic Gulf from 53 Ma, por-traying the onset of the second phase of rifting between Australia and Antarctica, to ever-subsiding margins and deepening, to the present continental and ever-widening ocean/continent configuration.