Pleistocene lake sediments in the Great Basin typically contain little organic carbon, and thus are difficult to date reliably by conventional radioccarbon methods. Paleoenvironmental data are abundant in these sediments, but are of limited value without adequate age controls. With the advent of accelerator-mass spectrometer (AMS) radiocarbon dating, it is now possible to date these paleolacustrine sediments. AMS dates were obtained on sediment cores from the Bonneville, Franklin, and Lahontan Basins. In the Bonneville Basin, the AMS-based chronology compares well with other chronologies constructed from dated shore-zone features. In the Bonneville and Franklin basins, AMS dates delimit unconformities not apparent by other means. We found that dispersed organic carbon from sediments deposited during relatively freshwater intervals provided apparently reliable AMS radiocarbon dates. Carbonate microfossils from the Lahontan Basin also produced results that appear reasonable, while bulk carbonate yielded erroneous results.
Bibliographical noteFunding Information:
We thank D. J. Donahue, A. Hatheway, A. J. T. Jull, T. Linick of the NSF Accelerator Facility, Univ. Arizona for their assistance in obtaining AMS dates from Great Salt Lake and Ruby Marshes. M. Tamers and BETA Analytic provided the AMS dates from Carson Lake. Partial support for the work at Carson Lake was provided by NSF grant BNS-8704094 to R. L. Kelly, Department of Anthropology, University of Louisville. J. O. Davis identified the Mazama tephra from the Ruby Marshes. B. Allen, J. P. Bradbury, R. B. Brown, B. L. Fine Jacobs, V. Markgraf, J. I. Mead, and E. Theriot assisted in obtaining sediment cores. C. G. Oviatt, D. R. Currey, D. K. Grayson, C. A. Repenning, P. A. Meyers, and W. R. Farrand provided useful discussions and/or manuscript reviews.
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