Pliocene climate change of the Southwest Pacific and the impact of ocean gateways.

Karas, Cyrus, Nürnberg, Dirk , Tiedemann, Ralf and Garbe-Schönberg, Dieter (2011) Pliocene climate change of the Southwest Pacific and the impact of ocean gateways. Earth and Planetary Science Letters, 301 (1-2). pp. 117-124. DOI 10.1016/j.epsl.2010.10.028.

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Abstract

The transition from the early Pliocene “Warmhouse” towards the present “Icehouse” climate and the role of Gateway dynamics are intensively debated. Both, the constrictions of the Central American Seaway and the Indonesian Gateway affected ocean circulation and climate during the Pliocene epoch. Here, we use combined δ18O and Mg/Ca ratios of planktonic foraminifera (marine protozoa) from surface and subsurface levels to reconstruct the thermal structure and changes in salinities from the Southwest Pacific Deep Sea Drilling Project (DSDP) Site 590B from 6.5 to 2.5 Ma. Our data suggest a gradual cooling of ~ 2 °C and freshening of the sea surface during ~ 4.6–4 Ma with an increased meridional temperature gradient between the West Pacific Warm Pool and the Southwest Pacific when the closing of the Central American Seaway reached a critical threshold. After ~ 3.5 Ma, the restricted Indonesian Gateway might have amplified the East Australian Current, allowing enhanced heat transport towards the Southwest Pacific with reduced meridional temperature gradients when the global climate gradually cooled. At the same time our data suggest a cooling and freshening of Subantarctic Mode Water (SAMW) or/and an increased northward flow of SAMW towards Site 590B, possibly a first step towards the present Antarctic Frontal System.

Document Type: Article
Keywords: Paleoceanography; Southwest Pacific; Pliocene; Foraminiferal Mg/Ca; Ocean gateways
Research affiliation: Kiel University
OceanRep > GEOMAR > FB1 Ocean Circulation and Climate Dynamics > FB1-P-OZ Paleo-Oceanography
OceanRep > The Future Ocean - Cluster of Excellence
Refereed: Yes
Open Access Journal?: No
DOI etc.: 10.1016/j.epsl.2010.10.028
ISSN: 0012-821X
Projects: Future Ocean
Date Deposited: 02 Dec 2010 10:53
Last Modified: 22 Feb 2017 12:31
URI: http://oceanrep.geomar.de/id/eprint/10275

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