A 225 kyr record of dust supply, paleoproductivity and the oxygen minimum zone from the Murray Ridge (northern Arabian Sea)

Abstract

Abstract Analysis of a (15 m long) sediment core recovered from the Murray Ridge (northern Arabian Sea) reveals a 225,000 year record of climate-induced variations in surface water productivity, mid-water ventilation, and dust input in the northern Arabian Sea. Productivity and dust input records closely resemble those from the Owen Ridge and Oman Margin. Also the phase lag of ∼10 kyr between maximum productivity and precession minimum is in phase with the summer monsoon upwelling record from the Owen Ridge and the Oman Margin. This implies that the productivity variations in the northern Arabian Sea during the last 225 kyr are primarily controlled by changes in the Indian Ocean summer monsoon. The winter monsoon obviously played a minor role in the productivity history of the northern Arabian Sea. Another result from this study is that the Mg Al record from the Murray Ridge nicely documents the post-glacial flooding of the Persian Gulf, which is the main glacial source for dolomite dust in this region. Finally, it is concluded that the intensity of the OMZ co-varies with surface water productivity, being weak during periods of reduced summer monsoon, especially during glacial periods.