Molybdenum accumulation in Cariaco basin sediment over the past 24 k.y.: Arecord of water-column anoxia and climate

Molybdenum (Mo) concentrations in a sediment core from the Cariaco basin on the Venezuelan continental shelf can be partitioned between a marine fract ion and a terrigenous fraction. The accumulation rate of the marine fractio n of Mo increased abruptly 15 000 calendar years ago (15 ka), from <0.5 mu g.cm(-2).yr(-1) to >4 mu g.cm(-2).yr(-1), and then decreased abruptly at 9 ha, The accumulation rate remained high throughout this 6 k.y. period, but exhibited maxima at 15-14 and 12.5 ka, corresponding in time to meltwater p ulse LA into the Gulf of Mexico and the onset of the Younger Dryas cold eve nt, respectively The marine fraction of Mo is interpreted in terms of redox conditions of bottom water, as dictated by both the flux of settling organ ic matter and bottom-water residence time. Correspondence between geochemic al extremes in this core with changes in sea level and global climate demon strates the high degree to which this ocean-margin basin has responded to t he paleoceanographic regime throughout the past 24 k.y.