DESERT WETLAND MOISTURE SOURCES DURING THE LATE PLEISTOCENE IN THE AMERICAN SOUTHWEST
Stable oxygen and carbon isotopes of fossil teeth are commonly used to investigate the paleoclimate of past environments and paleoecology of past fauna. Preserved δ18O and δ13C of interstitial carbonate in tooth enamel apatite depend on local moisture and food sources accessed during tooth formation. To identify the moisture source stabilizing paleowetland development, enamel samples were obtained from late Pleistocene Equus and Bison collected by the SBCM from the upper Las Vegas Wash, from geologic units corresponding with wet/cool periods. Tooth sections were subsampled prior to δ18O and δ13C analyses to assess seasonal zoning patterns.
δ18O values range from 19.71% to 28.86% V-SMOW, indicating an increase in spring/summer precipitation δ18O. Mean δ13Cdiet values range from -16.53% to -21.73% V-PDB, implying these genera were mixed C3/C4-feeders. Preliminary data suggest OOT is the primary source of moisture establishing paleowetlands in the American Southwest deserts during the late Pleistocene. Past desert ecosystems relied heavily on wetlands and determining the moisture source responsible for increased groundwater discharge is crucial for assessing paleowetland development.