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| Titel |
High Arabian Sea productivity conditions during MIS 13 – odd monsoon event or intensified overturning circulation at the end of the Mid-Pleistocene transition? |
| VerfasserIn |
M. Ziegler, L. J. Lourens, E. Tuenter, G.-J. Reichart |
| 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 ; 6, no. 1 ; Nr. 6, no. 1 (2010-01-29), S.63-76 |
| Datensatznummer |
250003325
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| Publikation (Nr.) |
 copernicus.org/cp-6-63-2010.pdf |
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| Zusammenfassung |
| Marine isotope stage (MIS) 13 (~500 000 years ago) has been
recognized as atypical in many paleoclimate records and, in
particular, it has been connected to an exceptionally strong summer
monsoon throughout the Northern Hemisphere. Here, we present a
multi-proxy study of a sediment core taken from the Murray Ridge at
an intermediate water depth in the northern Arabian Sea that covers
the last 750 000 years. Our results indicate that primary
productivity conditions were anomalously high during MIS 13 in the
Arabian Sea and led to extreme carbonate dissolution and
glauconitization in the deep-sea sediments. These observations could
be explained by increased wind driven upwelling of nutrient-rich
deep waters and, hence, by the occurrence of an exceptionally strong
summer monsoon event during MIS 13, as it was suggested in earlier
studies. However, ice core records from Antarctica demonstrate that
atmospheric methane concentrations, which are linked to the extent
of tropical wetlands, were relatively low during this period. This
constitutes a strong argument against an extremely enhanced global
monsoon circulation during MIS 13 which, moreover, is in contrast
with results of transient climate modelling experiments. As an
alternative solution for the aberrant conditions in the Arabian Sea
record, we propose that the high primary productivity was probably
related to the onset of an intensive meridional overturning
circulation in the Atlantic Ocean at the end of the Mid-Pleistocene
transition. This may have led to an increased supply of
nutrient-rich deep waters into the Indian Ocean euphotic zone,
thereby triggering the observed productivity maximum. |
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