Short-term Antarctic ice-sheet dynamics during the late Oligocene

Abstract Palaeoceanographic records spanning the Oligocene provide insights into Antarctic ice-sheet dynamics in a world warmer-than-today, allowing us to improve future climate projections linked to global warming. Here, we present a high-resolution multi-proxy record from ODP Site 689 (Maud Rise, Southern Ocean), to investigate the short-term Antarctic ice-sheet variability during the late Oligocene. Our oxygen isotope composition of sea water record reflects large, obliquity-paced ice volume fluctuations from 26.2 to 25.2 Ma. These fluctuations would have resulted in changes in the types of rocks eroded as the Antarctic ice-sheet advanced/retreated. Indeed, the radiogenic isotopic compositions of neodymium and lead co-vary with the oxygen isotopes for most of the record and identify changes in sediment provenance and weathering rates linked to advances and retreats of the Antarctic ice-sheet. At the same time, the stable incongruent lead isotope signal observed confirms the presence of a major East Antarctic ice-sheet during the late Oligocene.