HR: 0800h
AN: PP31A-1512    [Abstracts]
TI: Nitrogen and Hydrogen Isotope Records for the Last 18-kyr from a Southern Alaska Lake
AU: * Liu, Z
EM: Zhonghui_Liu@brown.edu
AF: Brown University, Department of Geological Sciences 324 Brook St., Providence, RI 02912 United States
AU: Huang, Y
EM: Yongsong_Huang@brown.edu
AF: Brown University, Department of Geological Sciences 324 Brook St., Providence, RI 02912 United States
AU: Clarke, G H
EM: gclarke@life.uiuc.edu
AF: University of Illinois, Departments of Plant Biology and Geology 505 South Goodwin Avenue, Urbana, IL 61801 United States
AU: Hu, F
EM: fshu@life.uiuc.edu
AF: University of Illinois, Departments of Plant Biology and Geology 505 South Goodwin Avenue, Urbana, IL 61801 United States
AB: To investigate Holocene climate variability in southern Alaska, an area sensitive to changes in atmosphere-ocean interactions, we have analyzed nitrogen and hydrogen isotopes from a sediment core recovered from Ongoke Lake (59°15'N, 159°25'W, 400 m a.s.l,). Bulk nitrogen isotopic values varied between 1.8 permil and 4.3 permil for the last 18 ka, with heavier values occurring at about 8-1 ka. Hydrogen isotopic values of n-C16 fatty acids recorded a ca. 30 permil change with higher values at about 8-6 ka. Hydrogen isotopic values became more negative over the past 6 ka, suggesting late-Holocene climatic cooling in southern Alaska. The long-term variation of hydrogen and nitrogen isotopes in the Holocene may have also been affected by changes in vegetation types, in addition to climatic factors such as temperature and moisture balance. Strong but brief negative excursions occurred at 12.5, 10.5, 8.2 and 2.0 ka in the records of fatty acid hydrogen isotopes, bulk nitrogen isotopes, ratios of long-chain acid vs. short chain acid content, and long-chain acid isotopic fractionation factor.
DE: 1041 Stable isotope geochemistry (0454, 4870)
DE: 3344 Paleoclimatology (0473, 4900)
DE: 4914 Continental climate records
DE: 4942 Limnology (0458, 1845, 4239)
SC: Paleoceanography and Paleoclimatology [PP]
MN: Fall Meeting 2005