HR: 1340h
AN: PP33B-0929    [Abstracts]
TI: Age Models for a Continous 250-kyr Quaternary Lacustrine Record from Bear Lake, Utah-Idaho
AU: * Colman, S M
EM: scolman@d.umn.edu
AF: Large Lakes Observatory, University of Minnesota Duluth, Duluth, MN 55812 United States
AU: Kaufman, D S
AF: Department of Geology, Northern Arizona University, Flagstaff, AZ 86011 United States
AU: Bright, J
AF: Department of Geology, Northern Arizona University, Flagstaff, AZ 86011 United States
AU: Heil, C
AF: Graduate School of Oceanography, University of Rhode Island, Narragansett, RI 02882 United States
AU: King, J W
AF: Graduate School of Oceanography, University of Rhode Island, Narragansett, RI 02882 United States
AU: Dean, W E
AF: U.S. Geological Survey, MS 980, Box 25046, Denver Federal Center, Denver, CO 80225 United States
AU: Rosenbaum, J R
AF: U.S. Geological Survey, MS 980, Box 25046, Denver Federal Center, Denver, CO 80225 United States
AU: Forester, R M
AF: U.S. Geological Survey, MS 980, Box 25046, Denver Federal Center, Denver, CO 80225 United States
AU: Bischoff, J L
AF: U.S. Geological Survey, MS 910, 345 Middlefield Rd,, Menlo Park, CA 94025 United States
AU: Perkins, M
AF: Deptartment of Geology, University of Utah, Salt Lake City, UT 84112 United States
AU: McGeehin, J P
AF: U.S. Geological Survey, National Center MS 955, Reston, VA 20192 United States
AB: The Quaternary sediments sampled by continuous 120-m-long drill cores from Bear Lake (Utah-Idaho) comprise one of the longest lacustrine sequences recovered from an extant lake. The cores serve as a good case study for construction of age models for sequences that extend beyond the range of radiocarbon dating. From a wide variety of potential age indicators, we selected a combination of radiocarbon ages, magnetic excursions (correlated to a standard sequence), and a single Uranium-series age to develop a "basic" age model. Data omitted from the basic age model include amino acid age estimates, which have a large amount of scatter, and tephrochronology correlations, which have large uncertainties. The basic age model suggests that the cored Bear Lake record is continuous back to about 250 ka. We also compared ages derived from the basic age model for inferred major glacial-interglacial climate events with events from other paleoclimate records (e.g., SPECMAP and Devils Hole). These comparisons support the accuracy of the basic age model and provide a degree of justification for using climate correlations as control points in age modeling. Doing so yields a "tuned" age model that represents our current best estimate of the chronology of Quaternary sediment deposition in Bear Lake.
DE: 9810 New fields (not classifiable under other headings)
SC: Paleoceanography and Paleoclimatology [PP]
MN: 2004 AGU Fall Meeting