A multi-proxy, high resolution record of the Younger Dryas in Cariaco Basin
Abstract
The Cariaco Basin, located off the northern coast of Venezuela, provides an opportunity to examine the response of the tropics to the Younger Dryas (YD) climate reversal at high resolution. Though previous studies have utilized the sediment record of the basin to explore this interval, inconsistencies between some proxies complicate the interpretation of changes in surface water productivity, riverine input, and basin ventilation. Early oxygen isotope data allow for little to no YD cooling of surface waters in the basin, while more recent Mg/Ca data suggest a decrease of 3-4°C, equivalent to a return to glacial sea surface temperatures (SST). Regional data support a southward shift of the Intertropical Convergence Zone (ITCZ) during the YD, which could at least partially explain cooler SST through stronger trade winds and increased upwelling; however, standard paleoproductivity proxies yield conflicting interpretations of the direction and magnitude of productivity changes that would be expected of stronger upwelling. In addition, sediment concentrations of the redox-sensitive trace metal molybdenum and the presence of a limited benthic fauna in YD sediments both suggest some degree of bottom water oxygenation, contrary to the expected state of anoxia that is presently understood to be generated by high levels of surface productivity in the basin. We attempt to resolve some of these inconsistencies by presenting a high resolution, multi-proxy record of the YD in the Cariaco Basin from IMAGES Calypso core MD03-2621, including its onset and termination. Paired, multi-species Mg/Ca and oxygen isotope records provide sea surface temperature and sea surface salinity records, while benthic foraminiferal census and oxygen isotope data, combined with elemental data generated by scanning XRF, illuminate the nature of basin oxygenation and deep water conditions during this period. The timing and magnitude of paleoenvironmental changes in the Cariaco Basin during the YD can be expected to provide insights into the response of the tropics to abrupt climate changes.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2009
- Bibcode:
- 2009AGUFMPP13G..06G
- Keywords:
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- 1041 GEOCHEMISTRY / Stable isotope geochemistry;
- 1065 GEOCHEMISTRY / Major and trace element geochemistry;
- 4900 PALEOCEANOGRAPHY;
- 4901 PALEOCEANOGRAPHY / Abrupt/rapid climate change