Duration and Structure of the Past Four Interglaciations (original) (raw)

1997, Quaternary Research

, dated using alpha-spectromet-Reanalysis and additional dating of the Devils Hole d 18 O paleoric (AS) uranium-series methodology. More recently, a 36temperature record confirm that the last interglaciation in the cm-long core of vein calcite from Devils Hole, dated using Great Basin (the continental analog of marine isotopic substage thermal-ionization mass-spectrometric (TIMS) uranium-se-5e) lasted Ç22,000 yr, consistent with the Vostok paleotemperaries methodology (Ludwig et al., 1992), indicated that not ture record which suggests a duration of Ç19,000 yr for this event only the last interglaciation, but also the three interglaciain Antarctica. The three preceding interglaciations in the Devils tions preceding it, lasted Ç20,000 yr or longer (Winograd Hole record (analogs of marine isotopic substages 7e, 9c, and 11c) et al., 1992). range from 20,000 to 26,000 yr in duration. A Ç20,000-yr duration Whether past interglaciations lasted on the order of 10,000 for the last interglaciation is consistent with TIMS uranium-series yr, as indicated by marine d 18 O records, or twice as long, as dated sea-level high stands. Thus, the widely held view that intersuggested by continental stable isotopic paleotemperature glaciations were of 11,000-to 13,000-yr duration and constituted only about 10% of mid-to-late Pleistocene climatic cycles needs records (i.e., Vostok and Devils Hole), is mandatory backreexamination. The warmest portion of each interglaciation in the ground information in evaluating the likely duration of our Devils Hole time series is marked by a d 18 O plateau, signifying present interglacial climate and the magnitude of anthropoapparent climatic stability for periods of 10,000-to 15,000-yr duragenic alterations to it. Examination of evidence bearing on tion. ᭧ 1997 University of Washington. the validity of these divergent opinions is the first goal of this study. Discerning patterns in the structure of past interglaciations that might provide clues pertinent to the duration 141