HR: 08:20h
AN: V21C-02    [Abstracts]
TI: Terrestrial-marine Correlation of the 24 kyr BP Dawson Tephra: Implications for Dispersal and Preservation of Alaskan Tephra Deposits
AU: * Beget, J E
EM: ffjeb1@uaf.edu
AF: University of Alaska Fairbanks, Dept. of Geology and Geophysics and Alaska Volcano Observatory , Fairbanks, AK 99775 United States
AU: Pedersen, T F
EM: tfp@uvic.ca
AF: University of Victoria, Dept. of Earth and Ocean Sciences Elliot 166 P.O. Box 3055, Victoria, BC V8W 3P6 Canada
AU: Muhs, D
EM: dmuhs@usgs.gov
AF: U.S. Geological Survey, Federal Center MS 980 Box 25046, Denver, CO 80225 United States
AB: The Dawson tephra, radiocarbon-dated to ca. 24,000 yr BP, is as much as 50 cm thick in Pleistocene sediments in Yukon Territory of Canada, but is not found in nearby parts of Alaska. Nonetheless, the geochemical characteristics of the tephra suggested derivation from an Aleutian arc volcano (Westgate et al., 2000). Its source was unknown until proximal deposits were recognized at Emmons Lake Volcanic Center (ELVC) on the Alaska Peninsula (Mangan et al., 2003). We have identified Dawson tephra in ODP core 880B, collected in the Northeast Pacific Ocean. The Dawson tephra also occurs in discontinuous small pods in two new localities near Fairbanks in central Alaska. Our data suggest the Dawson tephra was dispersed from the ELVC principally to the southeast over the North Pacific , and then carried to the northeast by high altitude winds. Reconstructions of the volume and distribution of individual tephras or of arc-wide explosive volcanism in Alaska must incorporate data from proximal and distal terrestrial localities, as well as marine cores.
DE: 8404 Ash deposits
SC: Volcanology, Geochemistry, Petrology [V]
MN: 2004 AGU Fall Meeting