Late Quaternary Stratigraphy and Luminescence Geochronology of the Northeastern Mojave Desert
ARTICLE IN PRESS Quaternary International 166 (2007) 61–78 Late Quaternary stratigraphy and luminescence geochronology of the northeastern Mojave Desert Shannon A. Mahana,Ã, David M. Millerb, Christopher M. Mengesc, James C. Younta aUnited States Geological Survey, Box 25046 MS 974, Denver, CO 80225, USA bUnited States Geological Survey, 345 Middlefield Road, MS 973, Menlo Park, CA 94025, USA cUnited States Geological Survey, 520 N. Park Ave., Tucson, AZ 85719-5035, USA Available online 8 January 2007 Abstract The chronology of the Holocene and late Pleistocene deposits of the northeastern Mojave Desert have been largely obtained using radiocarbon ages. Our study refines and extends this framework using optically stimulated luminescence (OSL) to date deposits from Valjean Valley, Silurian Lake Playa, Red Pass, and California Valley. Of particular interest are eolian fine silts incorporated in ground- water discharge (GWD) deposits bracketed at 185–140 and 20–50 ka. Alluvial fan deposits proved amenable for OSL by dating both eolian sand lenses and reworked eolian sand in a matrix of gravel that occurs within the fan stratigraphy. Lacustrine sand in spits and bars also yielded acceptable OSL ages. These OSL ages fill gaps in the geochronology of desert deposits, which can provide data relevant to understanding the responses of several depositional systems to regional changes in climate. This study identifies the most promising deposits for future luminescence dating and suggests that for several regions of the Mojave Desert, sediments from previously undated landforms can be more accurately placed within correct geologic map units. Published by Elsevier Ltd. 1. Introduction Previous chronologic studies in the northeastern Mojave Desert area include magneto-stratigraphic studies and Extracting paleoclimatic and paleoenvironmental infor- tephrochronology of the upper Pliocene to middle Quatern- mation from terrestrial deposits is an important area of ary Tecopa beds (Hillhouse, 1987; Sarna-Wojcicki et al., Quaternary geologic research.
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