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Evolution of ocean circulation in the North Atlantic Ocean during the Miocene: impact of the Greenland ice sheet and the eastern Tethys seaway
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  • Quentin PILLOT,
  • Yannick Donnadieu,
  • Anta-Clarisse Sarr,
  • Jean-Baptiste Ladant,
  • Baptiste Suchéras-Marx
Quentin PILLOT

Corresponding Author:[email protected]

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Yannick Donnadieu
CEREGE (Centre Européen de Recherche et d'Enseignement des Géosciences de l'Environnement)
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Anta-Clarisse Sarr
CEREGE, Aix-Marseille University
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Jean-Baptiste Ladant
Laboratoire des Sciences du Climat et de l'Environnement
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Baptiste Suchéras-Marx
Aix-Marseille University, OSU Pythéas
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Modern Ocean is characterized by the formation of deep-water in the North Atlantic (i.e. NADW). This feature has been attributed to the modern geography, in which the Atlantic Ocean is a large basin extending from northern polar latitudes to the Austral Ocean, the latter enabling the connection of the otherwise isolated Atlantic with the Pacific and Indian Oceans. Sedimentary data date the establishment of the NADW between the beginning of the Eocene (∼49 Ma) and the beginning of the Miocene (∼23 Ma). The objective of this study is to quantify the impact of Miocene geography on NADW through new simulations performed with the earth system model IPSL-CM5A2. We specifically focus on the closure of the eastern Tethys seaway (dated between 22 and 14 Ma), which allowed the connection between the Atlantic and Indian Oceans, and on the Greenland ice sheet, whose earliest onset remains open to discussion but for which evidence suggest a possible existence as early as the Eocene. Our results show that the closure of the eastern Tethys seaway does not appear to impact the establishment of NADW, because waters from the Indian Ocean do not reach the NADW formation zone when the seaway is open. Conversely, the existence of an ice sheet over Greenland strengthens the formation of NADW owing to topography induced changes in wind patterns over the North Atlantic, which in turn, results in a larger exchange of water fluxes between the Arctic and the North Atlantic, and in a re-localization of deep-water formation areas.