The Nature of Late Pleistocence Climate Ameliorations in Eastern Beringia

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OPP-99-19048EliasOPP-00-02362Edwards OPP-00-02361BergerThis is a collaborative proposal with Principal Investigators from the Universities of Colorado, Alaska, and the Desert Research Institute. Large portions of Siberia, Alaska, and northwestern Canada formed an unglaciated land-mass during the late Pleistocene known as Beringia. Previous Beringian paleoclimatic studies have yielded only qualitative temperature estimates. There is a need to develop quantitative estimates to gain a better understanding of the magnitude and regional expression of climate change. The Principal Investigators will attempt to quantify the paleotemperatures through the analysis of fossil insects, pollen, and plant macrofossils using thermoluminescence (TL) dating. They will use the Mutual Climatic Range (MCR) method of fossil beetle analysis and paleobotanical studies to produce estimates of mean temperatures of the warmest (TMAX) and coldest months (TMIN), as well as estimates of mean annual temperature (MAT). They will reconstruct past environments at the five study sites in central and northern Alaska with sediments ranging in age from the end of isotope stage 6 to the Holocene. The Principal Investigators will focus on samples from just before and during the last interglacial interval. They will date sediments from 140-50 thousand years by TL and its newer variant, photon-stimulated-luminescence. Two research themes will be addressed. The first theme is to study the nature of the climatic transition of stage 6 to stage 5 and to determine where the Old Crow tephra fits in this sequence. The second research theme is to determine the nature of climatic amelioration in Beringia during the last interglacial period.