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Wednesday, November 11, 2009

J. Oster, I. P. Montañe, W. D. Sharp & K. M. Cooper, Earth Planet. Sci. Lett., Late Pleistocene California droughts during deglaciation and Arctic warming

Earth and Planetary Science Letters, (2009) in press; DOI: 10.1016/j.epsl.2009.10.003

Late Pleistocene California droughts during deglaciation and Arctic warming

Jessica Oster, Isabel P. Montañe (Geology Department, University of California, Davis, CA, U.S.A.), Warren D. Sharp (Berkeley Geochronology Center, Berkeley, CA, U.S.A.) and Kari M. Cooper (Geology Department, University of California, Davis, CA, U.S.A.)


Recent studies document the synchronous nature of shifts in North Atlantic regional climate, the intensity of the East Asian monsoon, and productivity and precipitation in the Cariaco Basin during the last glacial and deglacial period. Yet questions remain as to what climate mechanisms influenced continental regions far removed from the North Atlantic and beyond the direct influence of the inter-tropical convergence zone. Here, we present U-series calibrated stable isotopic and trace element time series for a speleothem from Moaning Cave on the western slope of the central Sierra Nevada, California that documents changes in precipitation that are approximately coeval with Greenland temperature changes for the period 16.5 to 8.8 ka.
From 16.5 to 10.6 ka, the Moaning Cave stalagmite proxies record drier and possibly warmer conditions, signified by elevated δ18O, δ13C, [Mg], [Sr], and [Ba] and more radiogenic 87Sr/86Sr, during Northern Hemisphere warm periods (Bølling, early and late Allerød) and wetter and possibly colder conditions during Northern Hemisphere cool periods (Older Dryas, Inter-Allerød Cold Period, and Younger Dryas). Moaning Cave stable isotope records indicate that wet conditions persisted in this area well beyond 11.5 ka, suggesting the effects of the Younger Dryas event may have been longer lived in the western Sierra Nevada than in Greenland. However, a shifting drip center and corresponding change in seepage water routing may have influenced the trace element records between 10.6 and 9.6 ka. Linkages between northern high-latitude climate and precipitation in the Sierra Nevada suggested here could indicate that, under conditions of continued global warming, this drought-prone region may experience a reduction in Pacific-sourced moisture.

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