Ocean freshening near the end of the Mesozoic

Radmacher, Wiesława, Niezgodzki, Igor, Gilabert, Vicente, Knorr, Gregor, Buchs, David M. ORCID: https://orcid.org/0000-0001-8866-8125, Arz, José A., Arenillas, Ignacio, Pearce, Martin A., Tyszka, Jarosław, Mikołajczak, Mateusz, Vásquez, Osmín J., Ashckenazi-Polivoda, Sarit, Abramovich, Sigal, Niechwedowicz, Mariusz and Mangerud, Gunn 2025. Ocean freshening near the end of the Mesozoic. Nature Communications 16 (1) , 7238. 10.1038/s41467-025-62189-9

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Abstract

Paleogeographic changes have significantly shaped ocean circulation and climate dynamics throughout Earth’s history. This study integrates geological proxies with climate simulations to assess how ocean gateway evolution influenced ocean salinity near the end of the Mesozoic (~66 Ma). Our modeling results demonstrate that 1) Central American Seaway shoaling reorganizes ocean currents, and 2) Arctic marine gateway restrictions, confining Arctic–Global Ocean exchange exclusively to the Greenland–Norwegian Seaway, drive Arctic Ocean surface freshening and southward outflow of buoyant, low-salinity waters. However, only the combined effect of these two factors leads to both Arctic freshening and increased water mass stratification in the Greenland–Norwegian Seaway, proto-North Atlantic, and the Western Tethys. This scenario aligns with Maastrichtian palynological, micropaleontological, and geochemical records from high- and low-latitude sites. Our findings highlight the profound impact of these latest Cretaceous paleogeographic reconfigurations in altering global salinity patterns, underscoring their role as key drivers of global climate dynamics.

Item Type:	Article
Date Type:	Publication
Status:	Published
Schools:	Schools > Earth and Environmental Sciences
Publisher:	Nature Research
ISSN:	2041-1723
Date of First Compliant Deposit:	12 August 2025
Date of Acceptance:	14 July 2025
Last Modified:	13 Aug 2025 09:00
URI:	https://orca.cardiff.ac.uk/id/eprint/180379

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