Deglacial Neodymium Isotopic Ratios in the Florida Straits and the Response of Intermediate Waters to Reduced Meridional Overturning Circulation
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The relationship between intermediate watermass response to Atlantic Meridonial Overturning Circulation (AMOC) during two abrupt cooling events of the last deglacial, the Younger Dryas (YD) and Heinrich Event 1 (H1) is controversial and has been studied using conventional paleo-circulation tracers. In this study we measure Nd isotopes in sediments of the Florida Straits to investigate this discrepancy. Nd isotope ratios in the authigenic component of marine sediments are thought to be a reliable tracer of past changes in ocean circulation. We will use the Nd isotopic ratios of Fe-Mn oxide leachate of deep-sea sediments (representative of the seawater fraction of Nd) to understand the behavior of AAIW during the YD and H1 climate events. Two cores within the Florida Straits are selected because this site has been exposed to a combination of re-circulated North Atlantic subtropical gyre waters and AAIW. Our preliminary data suggest that the northward incursion of AAIW was weaker during the YD and H1 events. Specifically, ?Nd values are significantly lower during cold periods (i.e., YD and H1), than during the warmer Holocene epoch. This is consistent with interpretation of S 18 O analyses on sediments from the same cores. Such a trend supports the idea that during the Younger Dryas, there was a reduction within the Florida Current of the flow of intermediate, southern-sourced waters.
Antarctic Intermediate Water
North Atlantic Deep Water
Atlantic Meridonial Overturning Circulation
Heinrich Event 1
Franklin, Alyssa L. (2010). Deglacial Neodymium Isotopic Ratios in the Florida Straits and the Response of Intermediate Waters to Reduced Meridional Overturning Circulation. Texas A&M University. Available electronically from