Abstract
Combining U k 37 0 - and TEX 86 -derived temperatures and oxygen isotopic values of mixed-layer and thermocline species from the IODP site U1338 (East Equatorial Pacific) and ODP Site 806 (West Equatorial Pacific) we assess the evolution of the zonal sea-surface temperature gradients and thermocline depth across the equatorial Pacific from the late Miocene through the Pleistocene. Data suggest a long-term shoaling of the thermocline along the equator throughout the Miocene–Pliocene that accelerated around 5.3 Ma. We identify a critical transition at about 3.8 Ma from a El-Niño-like-dominated mean state during the late Miocene and early Pliocene to a La-Niña-like-dominated state during the late Pliocene–Pleistocene. This transition coincides with the restriction of the Indonesian seaway and the onset of ice growth in the northern hemisphere and in Antarctica that led to the long-term strengthening of the Walker circulation and affected low-latitude zonal gradient.
| Original language | English |
|---|---|
| Pages (from-to) | 242-252 |
| Number of pages | 11 |
| Journal | Journal of Sedimentary Research |
| Volume | 89 |
| Issue number | 3 |
| DOIs | |
| Publication status | Published - 25 Mar 2019 |
Funding
We thank the European Consortium for Ocean Research Drilling (ECORD) for the ECORD Grant. We are also grateful to Anchelique Mets and Jort Ossebaar for support with the TEX86 measurements. We finally want to thank Fabrice Minoletti for developing the separation technique necessary to perform the isotopic measurements on Noelaerhabdaceae calcite. We also thank the Ocean and International Ocean Drilling Program (ODP and IODP) for providing samples from Sites 806 and U1338. SS and AS were supported by the Netherlands Earth System Science Center funded by the Dutch Ministry Science and Education (OCW). MAS was supported by CNRS (Centre National de la Recherche Scientifique) for salary.