Fox, LR;
Wade, BS;
Holbourn, A;
Leng, MJ;
Bhatia, R;
(2021)
Temperature gradients across the Pacific Ocean during the middle Miocene.
Paleoceanography and Paleoclimatology
, 36
(6)
, Article e2020PA003924. 10.1029/2020PA003924.
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Abstract
Sea surface temperatures (SSTs) of the tropical Pacific Ocean exert powerful controls on regional and global climates. Previous studies have suggested that during warm climate phases, the east-west temperature gradient collapsed. To date, there has been no high-resolution reconstruction of sea surface conditions in both the east and west Pacific Ocean during the Miocene Climate Optimum (MCO) and across the middle Miocene climate transition (MMCT); therefore, our understanding of the mean oceanographic state during this major global climatic shift is limited. Here, we present new SST reconstructions for the eastern Pacific Ocean (15.5–13.3 Ma) which show a clear east-west temperature gradient of ∼4°C during the warmest interval of the Neogene, implying that the oceanographic processes that produce the modern gradient were present and active. There is no shift in the east-west gradient across the MMCT indicating that the gradient was not impacted by global cooling and ice growth. We find a 2°C sea surface cooling in the eastern equatorial Pacific, that lags the benthic foraminiferal δ^{18}O positive shift by 150 kyr, indicating that tropical temperature did not decrease synchronously with the expansion of the Antarctic ice sheet. Reconstructed variations in the δ^{18}O composition of seawater, determined by combining our Mg/Ca and δ^{18}O records, reveal a freshening in the eastern Pacific Ocean after 13.8 Ma, suggesting changes in the hydrological cycle and in tropical fronts in response to the new icehouse regime.
| Type: | Article |
|---|---|
| Title: | Temperature gradients across the Pacific Ocean during the middle Miocene |
| Open access status: | An open access version is available from UCL Discovery |
| DOI: | 10.1029/2020PA003924 |
| Publisher version: | https://doi.org/10.1029/2020PA003924 |
| Language: | English |
| Additional information: | © 2021 The Authors. This is an open access article under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0/). |
| Keywords: | middle Miocene, equatorial Pacific Ocean, SST's, planktonic foraminifera, Mg/Ca, stable isotopes |
| UCL classification: | UCL UCL > Provost and Vice Provost Offices > UCL BEAMS UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences > Dept of Earth Sciences |
| URI: | https://discovery.ucl.ac.uk/id/eprint/10129766 |
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