Preprints
https://doi.org/10.5194/cp-2020-105
https://doi.org/10.5194/cp-2020-105

  20 Aug 2020

20 Aug 2020

Review status: this discussion paper is a preprint. It has been under review for the journal Climate of the Past (CP). The manuscript was not accepted for further review after discussion.

Early Pliocene deepening of the tropical Atlantic thermocline

Carolien Maria Hendrina van der Weijst1, Josse Winkelhorst1, Anna von der Heydt2, Gert-Jan Reichart1,3, Francesca Sangiorgi1, and Appy Sluijs1 Carolien Maria Hendrina van der Weijst et al.
  • 1Department of Earth Sciences, Utrecht University, 3584 CB Utrecht, the Netherlands
  • 2Department of Physics, Utrecht University, 3584CC Utrecht, the Netherlands
  • 3NIOZ Royal Netherlands Institute for Sea Research, 1797 SZ ‘t Horntje, the Netherlands

Abstract. The tropical thermocline may have played a crucial role in maintaining weaker sea surface temperature gradients during the early Pliocene and in the onset of late Pliocene northern hemisphere glaciation. Whereas the Pliocene Pacific thermocline evolution is well documented, complete records of Pliocene tropical Atlantic thermocline depths are limited to the Caribbean region. Here, we use the oxygen isotope gradient between surface to subsurface dwelling planktic foraminifera from Ocean Drilling Program Site 959 in the eastern equatorial Atlantic to track vertical changes in thermocline depth over the course of the Pliocene. This record shows that eastern equatorial Atlantic thermocline depth varied substantially during the early Pliocene, before finally deepening abruptly around 4.5 Ma to remain relatively stable until at least 2.8 Ma. Eastern equatorial Atlantic and Caribbean records are almost identical, suggesting a common control on the sudden step-wise thermocline deepening across the basin, in contrast to previous assumptions. The Pliocene evolution of the tropical Atlantic thermocline differs is remarkably from the Pacific, which is characterized by gradual basin-wide shoaling. It remains unclear what mechanisms were involved in the dichotomous thermocline evolutions. Whereas Central American Seaway closure may have shoaled the Pacific thermocline, it is not yet understood if and how this process may have deepened the Atlantic thermocline. A divergent evolution of temperatures of the source regions may explain the opposite thermocline developments observed, possibly amplified by a positive feedback loop involving tropical cyclone intensity.

Carolien Maria Hendrina van der Weijst et al.

 
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Status: closed
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Status: closed
Status: closed
AC: Author comment | RC: Referee comment | SC: Short comment | EC: Editor comment
Printer-friendly Version - Printer-friendly version Supplement - Supplement

Carolien Maria Hendrina van der Weijst et al.

Carolien Maria Hendrina van der Weijst et al.

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