From Greenhouse to Icehouse at the Wilkes Land Antarctic Margin: IODP Expedition 318

Abstract:

IODP Expedition 318 drilled an inshore to offshore transect of sites across the Antarctic Wilkes Land margin to provide a long-term record of Cenozoic Antarctic glaciation and its relationships with global climatic and oceanographic changes. The expedition recovered ~2000 m of high-quality middle Eocene–Holocene sediments from water depths between 400 and 4000 m at seven sites on the Wilkes Land rise and shelf. Sediment cores provide an insight into ~54 million years of Antarctic history starting with an ice-free subtropical east Antarctica during the late Eocene, and the first cooling during the middle Eocene, coeval with the first incursion of cold westward flowing waters across the southern Tasman Gateway. The cores also reveal the erosional consequences of the onset of the continent-wide glaciation during the Eocene-Oligocene transition, and its effect in rising sea level around the Antarctic coastlines. Starting in the earliest Oligocene (Oi-1 event), the icehouse sediments provide records of the subsequent waxing and waning of the ice sheets, sea ice, and ecosystems. These include times of past elevated temperatures and CO₂ concentrations (i.e., the early Pliocene) and unprecedented seasonal to annual resolution records of the last deglaciation that began ~10,000 y ago. Wilkes Land records should be complimentary to those from Prydz Bay (ODP Legs 119 and 188) and the Ross Sea (ANDRILL, CRP), allowing for variations between different east Antarctic ice sheet sectors to be assessed, which will provide a better understanding of East Antarctica’s role in the past, present, and future global climate system.