A 50 kyr record of eolian sedimentation in the Eastern Arabian Sea - Dust deposition changes synchronous with the Northern Hemisphere Climatic Oscillations

Abstract

The Late Pleistocene Northern Hemisphere (NH) climate was extremely variable, owing to the abrupt warm Dansgaard-Oeschger (D/O) events and cold Heinrich events in the Greenland and North Atlantic. Although the close coupling between the Indian monsoon and the Northern hemisphere climatic fluctuations has been previously reported from several western and northern Arabian Sea records, these millennial-scale climatic oscillations are not clearly defined in the Eastern Arabian Sea (EAS) possibly because many of the past records are from the continental margin which are vulnerable to sediment slumps and slides. Here, we present a 50 kyr eolian sedimentation record from a bathymetric high off Goa in the EAS, reconstructed using the environmental magnetic parameter S-ratio (a measure of the relative proportions of ferromagnetic and canted antiferromagnetic minerals) and the mass accumulation rate of iron and magnesium (FeMAR and MgMAR). S-ratio record shows striking similarity with the ?18O record from the Greenland GISP2 ice core, indicating the control of the temperature fluctuations of high northern latitudes on the low-latitude climate variability. The cold Heinrich events are marked by lowered S-ratios indicating less eolian input while the D/O interstadials are marked by increased S-ratios illustrating the intensified summer monsoon wind strength and the increased eolian supply during these periods. The mass accumulation rate of Mg and Fe reveals high values during 29-18 kyr reflecting the increased source area aridity and dust transport during the last glacial period. The spectral analysis of the S-ratio record reveals significant periodicities centered at 24 kyr and 1.3 kyr establishing the orbital and northern hemisphere controls on the EAS climate.