A 200,000-Year Record of Change in Oxygen Isotope Composition of Sulfate in a Saline Sediment Core, Death Valley, California☆

Abstract δ 18 O values of sulfate minerals from a 186-m core (past 200,000 years) in Death Valley varied from +9 to +23‰ (V-SMOW). Sulfates that accumulated in the past ephemeral saline lake, salt pans, and mud flats have relatively low δ 18 O values similar to those of present-day local inflows. Sulfates that accumulated during two perennial lake intervals, however, have higher δ 18 O values, reflecting changes in temperature, lake water levels, and/or sulfur redox reactions. Over the same time interval, the δ 18 O record for sulfate had excursions that bear similarities to those found for carbonate in the Death Valley core, marine carbonate (SPECMAP), and polar ice in the Summit ice core, Greenland. The δ 18 O record differed considerably from the records reported for carbonate at Owens Lake and Devils Hole, which probably relates to different water sources. Death Valley, Owens Lake, and Devils Hole are responding to the same climatic changes but manifesting them differently. In Death Valley sediments, the isotopic composition of sulfate may have potential as an indicator of paleoenvironmental changes.