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| Titel |
Oceanographic and monsoonal variability in the Arabian Sea during Dansgaard-Oeschger oscillations |
| VerfasserIn |
Andreas Lückge, Gaudenz Deplazes, Enno Schefuß, Jan-Berend W. Stuut, Jürgen Pätzold, Holger Kuhlmann, Georg Scheeder, Hartmut Schulz, Gerald H. Haug  |
| Konferenz |
EGU General Assembly 2013
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 15 (2013) |
| Datensatznummer |
250075442
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| Zusammenfassung |
| The Dansgaard-Oeschger oscillations and Heinrich events described in Greenland ice cores
and North Atlantic sediments are expressed in the climate of the tropics, for example, as
documented in Arabian Sea sediments. Given the strength of this teleconnection, we seek to
reconstruct its range of environmental impacts. We present geochemical, sedimentological as
well as micropaleontological data from core SO130-289KL from a water depth of 570 m off
the Indus mouth, spanning the past 80,000 years. Elemental and grain-size analyses
combined with end-member modeling consistently indicate that interstadials are
characterized by an increased contribution of fluvial suspension from the Indus River.
Decadal-scale shifts at climate transitions, such as onsets of interstadials, were coeval with
changes in productivity-related proxies such as alkenone concentrations. Stadials are
characterized by an increased contribution of aeolian dust from the Arabian Peninsula.
Heinrich events stand out as especially dry and dusty events, indicating a dramatically
weakened Indian summer monsoon and increased aridity. The hydrogen isotopic
composition of terrigenous plant lipids reflects that stadials/Heinrich events are the driest
phases whereas humid conditions seem to have prevailed during interstadials. The
stable oxygen isotopes of the surface-dwelling planktonic foraminifer G. ruber
and the thermocline dweller P. obliquiloculata show a strong correspondence to
Greenland ice core δ18O records. The deepwater stable oxygen isotope signal of
benthic foraminifera (U. peregrina and G. affinis) primarily reflects δ18O patterns
recorded in ice cores from Antarctica. Strong shifts in δ18O during stadials/Heinrich
events are attributed to frequent advances of oxygen-rich intermediate water masses
into the Arabian Sea originating from the southern ocean. Alkenone-derived SSTs
show initial abrupt shifts towards higher SSTs followed by cooler temperatures
during interstadials, which are probably connected to the onset of upwelling-like
processes. Our results strengthen the evidence that circum-North Atlantic temperature
changes translate to hydrological shifts in the tropics, with major impacts on regional
environmental conditions such as rainfall, river discharge and ocean margin anoxia
supported by changes in the supply of water masses from the southern hemisphere. |
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