Late Eocene to early Oligocene oxygen and carbon isotope records and biogenic barium accumulation rates in Maud Rise, Kerguelen Plateau and Agulhas Ridge@en

The late Eocene through early Oligocene (40-33 Ma) represents a transition from a warm-house to icehouse climate mode, with the expansion of Antarctic glaciation shortly after the Eocene/Oligocene (E/O) boundary. Identifying the driving mechanisms for this climatic event remains controversial and depends on a better understanding of how the different environmental changes correlate to each other. We investigate the spatial and temporal variation in export productivity based on biogenic Ba (bio-Ba) from different Ocean Drilling Program (ODP) Sites in the Southern Ocean focusing on possible mechanisms that controlled them as well as the correlation of export productivity changes to changes in the global carbon cycle. We document two significant Southern Ocean region high export productivity late-Eocene events (ca. 37 and 33.5 Ma). We propose that paleoceanographic changes that followed the Southern Ocean gateways opening, along with more variable increases in circulation driven by episodic growth and decay of the Antarctic ice sheet, drove enhanced Southern Ocean export production in the late Eocene through the early Oligocene.