Abstract

The Eocene (approx 56-34 Ma) and Oligocene (approx 34-23 Ma) Epochs encompass a 33-Myr time interval characterised by a major revolution in Earth’s climate from a Greenhouse to an Icehouse regime. The onset of Antarctic glaciation at the Eocene-Oligocene Transition (EOT; approx 33.7 Ma) is associated with evidence for rapidly decreasing atmospheric CO2 levels as well as major reorganisation of Southern Ocean tectonic gateways and ocean circulation patterns. In recent years, however, studies have suggested both the potential for Antarctic glaciation during the high pCO2-world of the Eocene and large-scale instability of the Antarctic ice sheets during the cool Oligocene, highlighting that the relationships between the fundamental drivers of high-latitude climate are far from straight forward.

The Eocene and Oligocene climate history of Antarctica is primarily known from a limited number of pelagic Southern Ocean sediment cores (e.g., Maud Rise and Kerguelen Plateau). However, in March 2010, IODP Expedition 318 sailed to the Wilkes Land margin of Antarctica and recovered a sedimentary drillcore section adjacent to the Wilkes Subglacial Basin that spans the Eocene and Oligocene. These cores provide unique insight into regional climate change on the Antarctic continent over this crucial time period and serve as a link between ice-proximal and ice-distal climate records of the Southern Ocean. I will discuss the Eocene-Oligocene erosional record of the Wilkes margin, as reconstructed using the neodymium isotopic composition of marine sediments. These data reveal both long-term and short-term regional climate variability on the East Antarctic margin through the Eocene-Oligocene time interval, suggesting a potentially mobile Antarctic ice sheet during this time.