Publication Date:
2016-08-04
Description:
Publication date: Available online 1 August 2016 Source: Quaternary Research Author(s): Rajeev Saraswat, Dinesh Kumar Naik, Rajiv Nigam, Anuruddh Singh Gaur We reconstruct centennial scale quantitative changes in surface seawater temperature (SST), evaporation-precipitation (from Mg/Ca and δ 18 O of surface dwelling planktic foraminifera), productivity (from relative abundance of Globigerina bulloides ), carbon burial (from %CaCO 3 and organic carbon [%C org ]) and dissolved oxygen at sediment–water interface, covering the entire Holocene, from a core collected from the eastern Arabian Sea. From the multi-proxy record, we define the timing, consequences and possible causes of the mid-Holocene climate transition (MHCT). A distinct shift in evaporation-precipitation (E-P) is observed at 6.4 ka, accompanied by a net cooling of SST. The shift in SST and E-P is synchronous with a change in surface productivity. A concurrent decrease is also noted in both the planktic foraminiferal abundance and coarse sediment fraction. A shift in carbon burial, as inferred from both the %CaCO 3 and %C org , coincides with a change in surface productivity. A simultaneous decrease in dissolved oxygen at the sediment–water interface, suggests that changes affected both the surface and subsurface water. A similar concomitant change is also observed in other cores from the Arabian Sea as well as terrestrial records, suggesting a widespread regional MHCT. The MHCT coincides with decreasing low-latitude summer insolation, perturbations in total solar intensity and an increase in atmospheric CO 2 .
Print ISSN:
0033-5894
Electronic ISSN:
1096-0287
Topics:
Geography
,
Geosciences
