Hydrological Changes in the Indian Ocean Around the Last Glacial Maximum and Deglaciation
Abstract
The tropical ocean plays a key role in the global climate system. However, changes in tropical circulation have far reaching and hitherto unknown effects which could trigger global changes in climate. Precisely dated reconstructions of past sea surface temperature (SST) changes are therefore mandatory in order to establish the exact phase between tropical and high latitude climate variability during past abrupt climate events. Few SST records are sufficiently detailed to constrain accurately the low latitude climatology around the last glacial maximum. Available results are presented from 2 high sedimentation rate cores (IMAGES MD9821-65 and MD9821-72) with additional material from older cruises. These cores are located within the inner part of the Indonesian arc and in the vicinity of the outflow straits (between Timor and Sumbawa). With high resolution records (about 100 yr.) for the past 20 kyr and lower resolution records back to 300 kyr., planktonic and benthic isotopic records set the general stratigraphy and the hydrology of surface and deep waters. Sea surface temperature is reconstructed using Mg/Ca content from G.ruber (analysed in Cambridge's ICP\-AES), foraminiferal assemblages (MAT) and alkenone unsaturation index Uḱ37. Sea surface salinity is derived from the coupled G.ruber δ 18O and Mg/Ca ratio. The time scale is constrained by AMS14C and the benthic foraminifera δ 18O. Preliminary results would indicate that at the initiation of the deglaciation SST leads planktic δ 18O by about 1 kyr but are in phase with benthic δ 18O. Similar lead of the benthic vs planktic δ 18O is also observed in other cores from the Indian Ocean.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2001
- Bibcode:
- 2001AGUFMPP12B..05C
- Keywords:
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- 1600 GLOBAL CHANGE;
- 4267 Paleoceanography;
- 4870 Stable isotopes;
- 4875 Trace elements