A 250,000-Year Climatic Record from Great Basin Vein Calcite: Implications for Milankovitch Theory

doi:10.1126/science.242.4883.1275

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Science 2 December 1988:
Vol. 242. no. 4883, pp. 1275 - 1280
DOI: 10.1126/science.242.4883.1275

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A 250,000-Year Climatic Record from Great Basin Vein Calcite: Implications for Milankovitch Theory

ISAAC J. WINOGRAD ¹, TYLER B. COPLEN ¹, BARNEY J. SZABO ², and ALAN C. RIGGS ²

¹ U.S. Geological Survey, National Center (432), Reston, VA 22092.
² U.S. Geological Survey, Denver Federal Center, Lakewood, CO 80225.

A continuous record of oxygen-18 ( $dgr$ ¹⁸O) variations in the continentalhydrosphere during the middle-to-late Pleistocene has been obtainedfrom a uranium-series dated calcitic vein in the southern GreatBasin. The vein was deposited from ground water that moved throughDevils Hole—an open fault zone at Ash Meadows, Nevada—between50 and 310 ka (thousand years ago). The configuration of the $dgr$ ¹⁸O versus time curve closely resembles the marine and Antarcticice core (Vostok) $dgr$ ¹⁸O curves; however, the U-Th dates indicatethat the last interglacial stage (marine oxygen isotope stage5) began before 147 ± 3 ka, at least 17,000 years earlierthan indicated by the marine $dgr$ ¹⁸O record and 7,000 years earlierthan indicated by the less well dated Antarctic $dgr$ ¹⁸O record.This discrepancy and other differences in the timing of keyclimatic events suggest that the indirectly dated marine $dgr$ ¹⁸Ochronology may need revision and that orbital forcing may notbe the principal cause of the Pleistocene ice ages.