4He in Bahamas Carbonates: A Link between Dust Export and North African Mega-droughts over the Last Millennium

Thursday, 18 December 2014: 5:45 PM
Atreyee Bhattacharya, University of California Los Angeles, Department of Earth, Planetary, and Space Sciences, Los Angeles, CA, United States, Sujoy Mukhopadhyay, University of California Davis, Davis, CA, United States, Adam C Maloof, Princeton University, Princeton, NJ, United States, Earle R Williams, Massachusetts Institute of Technology, Cambridge, MA, United States and Amato T Evan, Scripps Institute of Oceanography, La Jolla, CA, United States
4He is a well-established proxy of aeolian input. 4He measurements in carbonate mud from the north-western Andros Islands in the Bahamas and soil samples from North Africa provide a record of the broad trends in dust export to the Bahamas over the past millennium. The 4He-based dust record provides evidence that mineral dust export from the Sahara-Sahel region of North Africa increased during the second half of the 20th century, in association with the multi-decadal droughts that affected the Sahel region during this interval. Furthermore, the 4He-based dust export rates to the Bahamas are linked to broad scale wet and dry cycles in North Africa over the past millennium with high 4He fluxes are associated with mega-droughts of this period, suggesting that centennial patterns of dust export to the Caribbean could have been linked to persistent droughts in the recent past. We will compare the dust record in relation to existing high-resolution geochemical proxy observations of sub-Saharan aridity and dust emission/export patterns from terrestrial, lacustrine and marine environments as well as satellite and station based observations.

(The Helium analysis was conducted in the noble gas laboratory at Harvard University)