Climatic/hydrologic oscillations since 155,000 yr BP at Owens Lake, California, reflected in abundance and stable isotope composition of sediment carbonate

Sediment grain size, carbonate content, and stable isotopes in 70-cm-long (similar to 1500-yr) channel samples from Owens Lake core OL-92 record many oscillations representing climate change in the eastern Sierra Nevada region since 155,000 yr B,P, To first order, the records match well the marine delta(18)O record. At Owens Lake, however, the last interglaciation appears to span the entire period from 120,000 to 50,000 yr B,P,, according to our chronology, and was punctuated by numerous short periods of wetter conditions during an otherwise dry climate. Sediment proxies reveal that the apparent timing of glacial-interglacial transitions, notably the penultimate one, is proxy-dependent, In the grain-size and carbonate-content records this transition is abrupt and occurs at similar to 120,000 yr B,P, In contrast, in the isotopic records the transition is gradual and occurs between 145,000 and 120,000 yr B. P. Differences in timing of the transition are attributed to variable responses by proxies to climate change. (C) 1997 University of Washington.