HR: 1340h
AN: PP23A-1077    [Abstracts]
TI: Late Holocene Climatic Variability in Northern Kazakhstan: Preliminary Evidence From Lake Sediment Lithostratigraphic and Stable Isotope Analyses
AU: * Rosenmeier, M F
EM: mrosenme@pitt.edu
AF: University of Pittsburgh, Department of Geology and Planetary Science, 4107 O'Hara Street, Pittsburgh, PA 15260, United States
AU: Robinson, K D
EM: kdrst16@pitt.edu
AF: University of Pittsburgh, Department of Geology and Planetary Science, 4107 O'Hara Street, Pittsburgh, PA 15260, United States
AU: Sikora, M T
EM: mts11@pitt.edu
AF: University of Pittsburgh, Department of Geology and Planetary Science, 4107 O'Hara Street, Pittsburgh, PA 15260, United States
AU: Olsen, S L
EM: olsens@CarnegieMNH.Org
AF: Carnegie Museum of Natural History, Section of Anthropology, 5800 Baum Boulevard, Pittsburgh, PA 15206, United States
AB: In June and July 2006, eleven short (<150 centimeters) sediment cores were recovered from seven lakes within the Soltustik Qazaqstan oblast, northern Kazakhstan. To date, we have completed whole-core magnetic susceptibility measurements of the recovered sediments, as well as bulk geochemical measurements (percent organic matter, percent calcium carbonate, etc.). Basic core lithology was also determined by smear-slide mineralogy and visual inspection for Munsell color, texture and grain size, sedimentary structure, and biogenic features. Preliminary radiocarbon dates indicate recovery of high-resolution sediment records spanning the last ~2000 years. We anticipate that a future lake sediment coring campaign (with equipment designed to recover much longer cores) will permit collection of complete Holocene sections at all sites. Because of the high density of shell materials within these lakes, we also expect to generate continuous stable isotope data sets that, when coupled with sedimentological and biological analyses, will provide valuable climate information. Initial efforts have focused on sediment profiles from the Beloye basin. Evaporative loss from the lake is substantial as demonstrated by the nearly 10‰ enrichment of lake waters relative to local meteoric waters (springs, rivers, and rainfall). Temporal changes in the ¹⁸O/¹⁶O ratio of the lake waters should therefore be recorded in the oxygen isotopic composition of the abundant carbonate microfossils (ostracode and gastropod shells) preserved in the basin deposits. Preliminary oxygen isotope records from Ozero Beloye reveal δ¹⁸O values ranging from -5.9 to -3.4‰. Relatively low carbonate oxygen isotope values are documented between ~480 and 150 years before present. This period of low δ¹⁸O, roughly coincident with the Little Ice Age, may indicate greater moisture availability and/or decreased regional temperatures. Oxygen isotopic values in the Beloye sediment record were greatest prior to ~500 years before present and between 150 and 50 years before present, suggesting greater aridity and/or warmer conditions.
DE: 1605 Abrupt/rapid climate change (4901, 8408)
DE: 1616 Climate variability (1635, 3305, 3309, 4215, 4513)
DE: 1650 Solar variability (7537)
DE: 4914 Continental climate records
DE: 9320 Asia
SC: Paleoceanography and Paleoclimatology [PP]
MN: 2007 Fall Meeting