Reports

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

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Science  02 Dec 1988:
Vol. 242, Issue 4883, pp. 1275-1280
DOI: 10.1126/science.242.4883.1275

Abstract

A continuous record of oxygen-18 (δ18O) variations in the continental hydrosphere during the middle-to-late Pleistocene has been obtained from a uranium-series dated calcitic vein in the southern Great Basin. The vein was deposited from ground water that moved through Devils Hole—an open fault zone at Ash Meadows, Nevada—between 50 and 310 ka (thousand years ago). The configuration of the δ18O versus time curve closely resembles the marine and Antarctic ice core (Vostok) δ18O curves; however, the U-Th dates indicate that the last interglacial stage (marine oxygen isotope stage 5) began before 147 ± 3 ka, at least 17,000 years earlier than indicated by the marine δ18O record and 7,000 years earlier than indicated by the less well dated Antarctic δ18O record. This discrepancy and other differences in the timing of key climatic events suggest that the indirectly dated marine δ18O chronology may need revision and that orbital forcing may not be the principal cause of the Pleistocene ice ages.