Contrasting multi-proxy reconstructions of surface ocean hydrography in the Agulhas Corridor and implications for the Agulhas Leakage during the last 345,000 years
Planktonic d18O and Mg/Ca‐derived sea surface temperature (SST) records from the Agulhas Corridor off South Africa display a progressive increase of SST during glacial periods of the last three climatic cycles. The SST increases of up to 4°C coincide with increased abundance of subtropical planktoni...
| Autores: | , , , , , , |
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| Tipo de recurso: | artículo |
| Estado: | Versión publicada |
| Fecha de publicación: | 2010 |
| País: | España |
| Institución: | Universidad de Barcelona |
| Repositorio: | Dipòsit Digital de la UB |
| OAI Identifier: | oai:diposit.ub.edu:2445/98307 |
| Acceso en línea: | https://hdl.handle.net/2445/98307 |
| Access Level: | acceso abierto |
| Palabra clave: | Paleoceanografia Paleoclimatologia Oceanografia química Paleoceanography Paleoclimatology Chemical oceanography |
| Sumario: | Planktonic d18O and Mg/Ca‐derived sea surface temperature (SST) records from the Agulhas Corridor off South Africa display a progressive increase of SST during glacial periods of the last three climatic cycles. The SST increases of up to 4°C coincide with increased abundance of subtropical planktonic foraminiferal marker species which indicates a progressive warming due to an increased influence of subtropical waters at the core sites. Mg/Caderived SST maximizes during glacial maxima and glacial Terminations to values about 2.5°C above fullinterglacial SST. The paired planktonic d18O and Mg/Ca‐derived SST records yield glacial seawater d18O anomalies of up to 0.8 , indicating measurably higher surface salinities during these periods. The SST pattern along our record is markedly different from a U37 K′ ‐derived SST record at a nearby core location in the Agulhas Corridor that displays SST maxima only during glacial Terminations. Possible explanations are lateral alkenone advection by the vigorous regional ocean currents or the development of SST contrasts during glacials in association with seasonal changes of Agulhas water transports and lateral shifts of the Agulhas retroflection. The different SST reconstructions derived from U37 K′ and Mg/Ca pose a significant challenge to the interpretation of the proxy records and demonstrate that the reconstruction of the Agulhas Current and interocean salt leakage is not as straightforward as previously suggested. |
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