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| Titel |
Salinity changes in the Agulhas leakage area recorded by stable hydrogen isotopes of C37 alkenones during Termination I and II |
| VerfasserIn |
S. Kasper, M. T. J. van der Meer, A. Mets, R. Zahn, J. S. Sinninghe Damsté, S. Schouten |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1814-9324
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| Digitales Dokument |
URL |
| Erschienen |
In: Climate of the Past ; 10, no. 1 ; Nr. 10, no. 1 (2014-02-05), S.251-260 |
| Datensatznummer |
250116908
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| Publikation (Nr.) |
 copernicus.org/cp-10-251-2014.pdf |
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| Zusammenfassung |
| At the southern tip of Africa, the Agulhas Current reflects back into the
Indian Ocean causing so-called "Agulhas rings" to spin off and release
relatively warm and saline water into the South Atlantic Ocean. Previous
reconstructions of the dynamics of the Agulhas Current, based on paleo-sea
surface temperature and sea surface salinity proxies, inferred that Agulhas
leakage from the Indian Ocean to the South Atlantic was reduced during
glacial stages as a consequence of shifted wind fields and a northwards
migration of the subtropical front. Subsequently, this might have led to a
buildup of warm saline water in the southern Indian Ocean. To investigate
this latter hypothesis, we reconstructed sea surface salinity changes using
alkenone δD, and paleo-sea surface temperature using
TEXH86 and UK'37, from two sediment cores
(MD02-2594, MD96-2080) located in the Agulhas leakage area during Termination
I and II. Both UK'37 and TEXH86 temperature
reconstructions indicate an abrupt warming during the glacial terminations,
while a shift to more negative δDalkenone values of
approximately 14‰ during glacial Termination I and II is also
observed. Approximately half of the isotopic shift can be attributed to the
change in global ice volume, while the residual isotopic shift is attributed
to changes in salinity, suggesting relatively high salinities at the core
sites during glacials, with subsequent freshening during glacial
terminations. Approximate estimations suggest that
δDalkenone represents a salinity change of ca. 1.7–1.9
during Termination I and Termination II. These estimations are in good
agreement with the proposed changes in salinity derived from previously
reported combined planktonic Foraminifera δ18O values and
Mg/Ca-based temperature reconstructions. Our results confirm
that the δD of alkenones is a potentially suitable tool to
reconstruct salinity changes independent of planktonic Foraminifera
δ18O. |
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