25 Jul 2023
 | 25 Jul 2023
Status: this preprint is open for discussion and under review for Climate of the Past (CP).

Late Eocene to early Oligocene productivity events in the proto-Southern Ocean as drivers of global cooling and Antarctica glaciation

Gabrielle Rodrigues de Faria, David Lazarus, Johan Renaudie, Jessica Stammeier, Volkan Özen, and Ulrich Struck

Abstract. The Eocene-Oligocene transition (ca 40–33 Ma) marks a transformation from an ice-free to an ice-house climate mode that is well recorded by oxygen stable isotopes and sea surface temperature proxies. Opening of the Southern Ocean gateways and decline in atmospheric carbon dioxide have been hypothesised as possible triggers of the major climate shift during the Cenozoic. However, identifying the driving mechanisms remains controversial and depends on a better understanding of how the different environmental changes correlate. In this study, we investigate the spatio-temporal variation in export productivity using 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 SO region high export productivity late-Eocene events (ca. 37 and 33.5 Ma) correlated to pronounced changes in global atmospheric pCO2. We propose that paleoceanographic changes that followed Southern Ocean gateway openings, along with more variable increases in circulation driven by episodic expansion and decline of the Antarctic ice sheet, drove enhanced SO export production in the late Eocene through basal Oligocene. These factors may have driven the episodic reduction of atmospheric carbon dioxide and contributed to Antarctic glaciation during the Eocene-Oligocene transition.

Gabrielle Rodrigues de Faria et al.

Status: open (until 11 Oct 2023)

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  • RC1: 'Comment on egusphere-2023-1276', Peter Bijl, 21 Sep 2023 reply

Gabrielle Rodrigues de Faria et al.

Data sets

Late Eocene to Early Oligocene Oxygen and Carbon Isotope Records and Biogenic Barium Accumulation Rates in Maud Rise, Kerguelen Plateau and Agulhas Ridge. Gabrielle R. Faria, David B. Lazarus, Johan Renaudie, Jessica Stammeier, Volkan Özen, and Ulrich Struck

Gabrielle Rodrigues de Faria et al.


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Short summary
Export productivity is part of the global carbon cycle and modulates the climate system via biological pump. About 34 million years ago, the Earth's climate had a dramatic climate change from a greenhouse state to an ice-house state with the establishment of ice sheets in Antarctica. Here, show important export productivity events in the Southern Ocean that preceded this climatic shift. Our results suggest that the biological pump played an important role in this critical climatic event.