Late Eocene Southern Ocean Cooling and Invigoration of Circulation Preconditioned Antarctica for Full-Scale Glaciation
During the Eocene-Oligocene Transition (EOT; 34–33.5 Ma), Antarctic ice sheets relatively rapidly expanded, leading to the first continent-scale glaciation of the Cenozoic. Declining atmospheric CO2 concentrations and associated feedbacks have been invoked as underlying mechanisms, but the role of t...
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ftunivutrecht:oai:dspace.library.uu.nl:1874/384409 2023-11-12T04:03:37+01:00 Late Eocene Southern Ocean Cooling and Invigoration of Circulation Preconditioned Antarctica for Full-Scale Glaciation Houben, Alexander J.P. Bijl, Peter K. Sluijs, Appy Schouten, Stefan Brinkhuis, Henk Marine Palynology Marine palynology and palaeoceanography Organic geochemistry 2019-05 image/pdf https://dspace.library.uu.nl/handle/1874/384409 en eng 1525-2027 https://dspace.library.uu.nl/handle/1874/384409 info:eu-repo/semantics/OpenAccess Antarctica dinoflagellate cysts Eocene-Oligocene transition ocean circulation paleothermometry Southern Ocean Taverne Geophysics Geochemistry and Petrology Article 2019 ftunivutrecht 2023-11-01T23:21:07Z During the Eocene-Oligocene Transition (EOT; 34–33.5 Ma), Antarctic ice sheets relatively rapidly expanded, leading to the first continent-scale glaciation of the Cenozoic. Declining atmospheric CO2 concentrations and associated feedbacks have been invoked as underlying mechanisms, but the role of the quasi-coeval opening of Southern Ocean gateways (Tasman Gateway and Drake Passage) and resulting changes in ocean circulation is as yet poorly understood. Definitive field evidence from EOT sedimentary successions from the Antarctic margin and the Southern Ocean is lacking, also because the few available sequences are often incomplete and poorly dated, hampering detailed paleoceanographic and paleoclimatic analysis. Here we use organic dinoflagellate cysts (dinocysts) to date and correlate critical Southern Ocean EOT successions. We demonstrate that widespread winnowed glauconite-rich lithological units were deposited ubiquitously and simultaneously in relatively shallow-marine environments at various Southern Ocean localities, starting in the late Eocene (~35.7 Ma). Based on organic biomarker paleothermometry and quantitative dinocyst distribution patterns, we analyze Southern Ocean paleoceanographic change across the EOT. We obtain strong indications for invigorated surface and bottom water circulation at sites affected by polar westward-flowing wind-driven currents, including a westward-flowing Antarctic Countercurrent, starting at about 35.7 Ma. The mechanism for this oceanographic invigoration remains poorly understood. The circum-Antarctic expression of the phenomenon suggests that, rather than triggered by tectonic deepening of the Tasman Gateway, progressive pre-EOT atmospheric cooling played an important role. At localities affected by the Antarctic Countercurrent, sea surface productivity increased and simultaneously circum-Antarctic surface waters cooled. We surmise that combined, these processes contributed to preconditioning the Antarctic continent for glaciation. Article in Journal/Newspaper Antarc* Antarctic Antarctica Drake Passage Southern Ocean Utrecht University Repository Antarctic Drake Passage Southern Ocean The Antarctic |
institution |
Open Polar |
collection |
Utrecht University Repository |
op_collection_id |
ftunivutrecht |
language |
English |
topic |
Antarctica dinoflagellate cysts Eocene-Oligocene transition ocean circulation paleothermometry Southern Ocean Taverne Geophysics Geochemistry and Petrology |
spellingShingle |
Antarctica dinoflagellate cysts Eocene-Oligocene transition ocean circulation paleothermometry Southern Ocean Taverne Geophysics Geochemistry and Petrology Houben, Alexander J.P. Bijl, Peter K. Sluijs, Appy Schouten, Stefan Brinkhuis, Henk Late Eocene Southern Ocean Cooling and Invigoration of Circulation Preconditioned Antarctica for Full-Scale Glaciation |
topic_facet |
Antarctica dinoflagellate cysts Eocene-Oligocene transition ocean circulation paleothermometry Southern Ocean Taverne Geophysics Geochemistry and Petrology |
description |
During the Eocene-Oligocene Transition (EOT; 34–33.5 Ma), Antarctic ice sheets relatively rapidly expanded, leading to the first continent-scale glaciation of the Cenozoic. Declining atmospheric CO2 concentrations and associated feedbacks have been invoked as underlying mechanisms, but the role of the quasi-coeval opening of Southern Ocean gateways (Tasman Gateway and Drake Passage) and resulting changes in ocean circulation is as yet poorly understood. Definitive field evidence from EOT sedimentary successions from the Antarctic margin and the Southern Ocean is lacking, also because the few available sequences are often incomplete and poorly dated, hampering detailed paleoceanographic and paleoclimatic analysis. Here we use organic dinoflagellate cysts (dinocysts) to date and correlate critical Southern Ocean EOT successions. We demonstrate that widespread winnowed glauconite-rich lithological units were deposited ubiquitously and simultaneously in relatively shallow-marine environments at various Southern Ocean localities, starting in the late Eocene (~35.7 Ma). Based on organic biomarker paleothermometry and quantitative dinocyst distribution patterns, we analyze Southern Ocean paleoceanographic change across the EOT. We obtain strong indications for invigorated surface and bottom water circulation at sites affected by polar westward-flowing wind-driven currents, including a westward-flowing Antarctic Countercurrent, starting at about 35.7 Ma. The mechanism for this oceanographic invigoration remains poorly understood. The circum-Antarctic expression of the phenomenon suggests that, rather than triggered by tectonic deepening of the Tasman Gateway, progressive pre-EOT atmospheric cooling played an important role. At localities affected by the Antarctic Countercurrent, sea surface productivity increased and simultaneously circum-Antarctic surface waters cooled. We surmise that combined, these processes contributed to preconditioning the Antarctic continent for glaciation. |
author2 |
Marine Palynology Marine palynology and palaeoceanography Organic geochemistry |
format |
Article in Journal/Newspaper |
author |
Houben, Alexander J.P. Bijl, Peter K. Sluijs, Appy Schouten, Stefan Brinkhuis, Henk |
author_facet |
Houben, Alexander J.P. Bijl, Peter K. Sluijs, Appy Schouten, Stefan Brinkhuis, Henk |
author_sort |
Houben, Alexander J.P. |
title |
Late Eocene Southern Ocean Cooling and Invigoration of Circulation Preconditioned Antarctica for Full-Scale Glaciation |
title_short |
Late Eocene Southern Ocean Cooling and Invigoration of Circulation Preconditioned Antarctica for Full-Scale Glaciation |
title_full |
Late Eocene Southern Ocean Cooling and Invigoration of Circulation Preconditioned Antarctica for Full-Scale Glaciation |
title_fullStr |
Late Eocene Southern Ocean Cooling and Invigoration of Circulation Preconditioned Antarctica for Full-Scale Glaciation |
title_full_unstemmed |
Late Eocene Southern Ocean Cooling and Invigoration of Circulation Preconditioned Antarctica for Full-Scale Glaciation |
title_sort |
late eocene southern ocean cooling and invigoration of circulation preconditioned antarctica for full-scale glaciation |
publishDate |
2019 |
url |
https://dspace.library.uu.nl/handle/1874/384409 |
geographic |
Antarctic Drake Passage Southern Ocean The Antarctic |
geographic_facet |
Antarctic Drake Passage Southern Ocean The Antarctic |
genre |
Antarc* Antarctic Antarctica Drake Passage Southern Ocean |
genre_facet |
Antarc* Antarctic Antarctica Drake Passage Southern Ocean |
op_relation |
1525-2027 https://dspace.library.uu.nl/handle/1874/384409 |
op_rights |
info:eu-repo/semantics/OpenAccess |
_version_ |
1782338137047957504 |