Decadal resolution record of sediment core M74/1b_944-6 (SL 163)

The Indian summer monsoon (ISM) is an important conveyor in the ocean-atmosphere coupled system on a transregional scale. Here we present a study of a sediment core from the northern Oman margin, revealing early- to mid Holocene ISM conditions on a near 20-year resolution. We assess multiple independent proxies indicative of sea surface temperatures (SST) during the upwelling season together with bottom water conditions. We use geochemical parameters, transfer functions of planktic foraminiferal assemblages and Mg/Ca paleothermometry and find evidence corroborating previous studies that upwelling intensity varies significantly in coherence to solar sunspot cycles. The dominant ~80-90-year Gleissberg cycle was apparently also affecting bottom water oxygen conditions. Although the interval from 8.4 to 5.8 ka B.P. is relatively short, the gradually decreasing trend of summer monsoon conditions was interrupted by short events of intensified ISM conditions. Results from both independent SST proxies are linked to phases of weaker OMZ conditions and enhanced carbonate preservation. This indicates that atmospheric forcing was intimately linked to bottom water properties and state of the OMZ on decadal time scales.