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Eocene‐Oligocene Intensification of the Deep Western Boundary Current in the North Atlantic Ocean

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posted on 2024-04-19, 09:51 authored by Andrew M Parent, Kristin D Chilton, Tim E van Peer, Steven M Bohaty, James F Spray, Howie D Scher, Paul A Wilson, Brian W Romans

The role played by ocean circulation in major transitions in Earth's climate is debated. Here, we investigate the physical evolution of the Deep Western Boundary Current (DWBC) in the western North Atlantic Ocean through the late Eocene‐to‐mid Oligocene (35−26 Ma) using terrigenous grain size and geochemistry records of marine sediment cores. Our records cover the most pivotal transition in Cenozoic climate history, the Eocene‐Oligocene Transition (EOT; ∼33.7 Ma), when Earth first became sufficiently cool to sustain large ice sheets on Antarctica. To assess changes in deep‐water circulation in the northwest Atlantic across the EOT, we assembled sortable silt (10–63 μm) grain‐size and Nd, Hf, and Pb radiogenic isotope records at two Integrated Ocean Drilling Program (IODP) drill sites on the Newfoundland ridges (Sites U1406 and U1411). These records reveal an overall gradual increase in sortable silt abundance (SS%) at both sites with no change in sediment provenance. We interpret a steady, long‐term invigoration of the DWBC, likely driven by deepening of the Greenland‐Scotland Ridge and resultant enhanced inflow of waters sourced from deep‐water production sites in the Nordic Seas to the North Atlantic Ocean. Our results do not support abrupt and widespread invigoration of bottom current activity in the North Atlantic synchronous with accelerated cooling and Antarctic ice growth at the EOT. Instead, our records suggest that the DWBC started to intensify before this pivotal event in Cenozoic climate history (at ∼35 Ma) and then further strengthened gradually across the EOT (∼34 Ma) and through the early‐to‐mid Oligocene (∼34‒26 Ma).

History

Author affiliation

College of Science & Engineering/Geography, Geology & Environment

Version

  • AM (Accepted Manuscript)

Published in

Paleoceanography and Paleoclimatology

Volume

39

Issue

4

Publisher

American Geophysical Union (AGU)

issn

2572-4517

eissn

2572-4525

Copyright date

2024

Available date

2024-04-19

Language

en

Deposited by

Dr Tim van Peer

Deposit date

2024-04-16

Rights Retention Statement

  • No

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