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Plio-Pleistocene glacial-interglacial productivity changes in the eastern equatorial Pacific upwelling system

Plio-Pleistocene glacial-interglacial productivity changes in the eastern equatorial Pacific upwelling system
Plio-Pleistocene glacial-interglacial productivity changes in the eastern equatorial Pacific upwelling system
The eastern equatorial Pacific Ocean (EEP) upwelling system supports >10% of the present-day global ocean primary production, making it an important component in Earth's atmospheric and marine carbon budget. Traditionally, it has been argued that since intensification of Northern Hemisphere glaciation (iNHG, ~2.7?Ma), changes in EEP productivity have predominantly depended on trade wind strength-controlled upwelling intensity. An alternative hypothesis suggests that EEP productivity is primarily controlled by nutrient supply from the high southern latitudes via mode waters. Here we present new high-resolution data for the latest Pliocene/early Pleistocene from Ocean Drilling Program Site 849, located within the equatorial divergence system in the heart of the EEP upwelling regime. We use carbon isotopes in benthic and planktic foraminiferal calcite and sand accumulation rates to investigate glacial-interglacial (G-IG) productivity fluctuations between 2.65 and 2.4?Ma (marine isotope stages (MIS) G1 to 94). This interval includes MIS 100, 98, and 96, three large-amplitude glacials (~1‰ in benthic ?18O) representing the culmination of iNHG. Our results suggest that latest Pliocene/early Pleistocene G-IG productivity changes in the EEP were strongly controlled by nutrient supply from Southern Ocean-sourced mode waters. Our records show a clear G-IG cyclicity from MIS 100 onward with productivity levels increasing from full glacial conditions and peaking at glacial terminations. We conclude that enhanced nutrient delivery from high southern latitudes during full glacial conditions together with superimposed intensified regional upwelling toward glacial terminations strongly regulated primary productivity rates in the EEP from MIS 100 onward.
planktic foraminifera, carbon isotopes, paleoproductivity, equatorial upwelling, eastern equatorial Pacific, Southern Ocean
0883-8305
453-470
Jakob, Kim A.
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Wilson, Paul A.
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Bahr, André
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Bolton, Clara T.
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Pross, Jörg
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Fiebig, Jens
2002fcc6-8c97-4f72-9f07-76efa9bd89ee
Friedrich, Oliver
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Jakob, Kim A.
8c240dc3-b25a-4bd4-a9c1-b8436f1e6ffa
Wilson, Paul A.
f940a9f0-fa5a-4a64-9061-f0794bfbf7c6
Bahr, André
ff113c9b-74d3-40e1-ba22-0ddb05ffda5e
Bolton, Clara T.
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Pross, Jörg
7c848424-852f-467b-90f0-19d4f8d4ae01
Fiebig, Jens
2002fcc6-8c97-4f72-9f07-76efa9bd89ee
Friedrich, Oliver
680f066c-a4b1-4647-beb3-281addc1ee17

Jakob, Kim A., Wilson, Paul A., Bahr, André, Bolton, Clara T., Pross, Jörg, Fiebig, Jens and Friedrich, Oliver (2016) Plio-Pleistocene glacial-interglacial productivity changes in the eastern equatorial Pacific upwelling system. Paleoceanography, 31 (5), 453-470. (doi:10.1002/2015PA002899).

Record type: Article

Abstract

The eastern equatorial Pacific Ocean (EEP) upwelling system supports >10% of the present-day global ocean primary production, making it an important component in Earth's atmospheric and marine carbon budget. Traditionally, it has been argued that since intensification of Northern Hemisphere glaciation (iNHG, ~2.7?Ma), changes in EEP productivity have predominantly depended on trade wind strength-controlled upwelling intensity. An alternative hypothesis suggests that EEP productivity is primarily controlled by nutrient supply from the high southern latitudes via mode waters. Here we present new high-resolution data for the latest Pliocene/early Pleistocene from Ocean Drilling Program Site 849, located within the equatorial divergence system in the heart of the EEP upwelling regime. We use carbon isotopes in benthic and planktic foraminiferal calcite and sand accumulation rates to investigate glacial-interglacial (G-IG) productivity fluctuations between 2.65 and 2.4?Ma (marine isotope stages (MIS) G1 to 94). This interval includes MIS 100, 98, and 96, three large-amplitude glacials (~1‰ in benthic ?18O) representing the culmination of iNHG. Our results suggest that latest Pliocene/early Pleistocene G-IG productivity changes in the EEP were strongly controlled by nutrient supply from Southern Ocean-sourced mode waters. Our records show a clear G-IG cyclicity from MIS 100 onward with productivity levels increasing from full glacial conditions and peaking at glacial terminations. We conclude that enhanced nutrient delivery from high southern latitudes during full glacial conditions together with superimposed intensified regional upwelling toward glacial terminations strongly regulated primary productivity rates in the EEP from MIS 100 onward.

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Accepted/In Press date: 2 March 2016
e-pub ahead of print date: 24 March 2016
Published date: 15 April 2016
Keywords: planktic foraminifera, carbon isotopes, paleoproductivity, equatorial upwelling, eastern equatorial Pacific, Southern Ocean
Organisations: Paleooceanography & Palaeoclimate

Identifiers

Local EPrints ID: 391014
URI: http://eprints.soton.ac.uk/id/eprint/391014
ISSN: 0883-8305
PURE UUID: c17b7ce5-ac31-4f67-817a-c6d6795e73c6
ORCID for Paul A. Wilson: ORCID iD orcid.org/0000-0001-6425-8906

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Date deposited: 05 Apr 2016 16:01
Last modified: 15 Mar 2024 03:05

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Contributors

Author: Kim A. Jakob
Author: Paul A. Wilson ORCID iD
Author: André Bahr
Author: Clara T. Bolton
Author: Jörg Pross
Author: Jens Fiebig
Author: Oliver Friedrich

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