Molybdenum Accumulation in Cariaco Basin Sediment Over the Past 24 k.y.: A Record of Water-Column Anoxia and Climate

Authors

Walter E. Dean, U.S. Geological Survey, MS 980, Federal Center, Denver, Colorado 80225, USA
David Z. Piper, U.S. Geological Survey, MS 902, 345 Middlefield Road, Menlo Park, California 94025, USA
Larry C. Peterson, University of Miami

Date of this Version

6-1999

Comments

Published in Geology; June 1999; v. 27; no. 6; p. 507–510; 4 figures.

Abstract

Molybdenum (Mo) concentrations in a sediment core from the Cariaco basin on the Venezuelan continental shelf can be partitioned between a marine fraction and a terrigenous fraction. The accumulation rate of the marine fraction of Mo increased abruptly 15 000 calendar years ago (15 ka), from <0.5 mg • cm^-2 • yr^-1 to >4 μg • cm^-2 • yr^-1, and then decreased abruptly at 9 ka. 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 pulse IA into the Gulf of Mexico and the onset of the Younger Dryas cold event, respectively. The marine fraction of Mo is interpreted in terms of redox conditions of bottom water, as dictated by both the flux of settling organic matter and bottom-water residence time. Correspondence between geochemical extremes in this core with changes in sea level and global climate demonstrates the high degree to which this ocean-margin basin has responded to the paleoceanographic regime throughout the past 24 k.y.