Late Eocene to early Oligocene productivity events in the proto-Southern Ocean as drivers of global cooling and Antarctica glaciation
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.
Status: final response (author comments only)
RC1: 'Comment on egusphere-2023-1276', Peter Bijl, 21 Sep 2023
- AC1: 'Reply on RC1', Gabrielle Rodrigues de Faria, 13 Dec 2023
- RC2: 'Comment on egusphere-2023-1276', Anonymous Referee #2, 22 Nov 2023
Late Eocene to Early Oligocene Oxygen and Carbon Isotope Records and Biogenic Barium Accumulation Rates in Maud Rise, Kerguelen Plateau and Agulhas Ridge. https://doi.pangaea.de/10.1594/PANGAEA.959619
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