Paper No. 3-1
Presentation Time: 8:05 AM
RE-VISITING LAKE MOJAVE USING A BASIN ANALYSIS APPROACH: TRYING TO RESOLVE A COMPLEX HISTORY OF LAKE LEVEL CHANGE
Glacial Lake Mojave has long been studied (e.g., Brown et al., 1990). A well-dated comparison, however, between lake sediment cores and beach, or near-shoreline, indicators is missing. As a result, lake depth estimates are unknown. Yet, understanding lake depth is key to estimating the volume of water required to fill Lake Mojave over time. And, knowing the volume of water in Lake Mojave over time will provide key information for calculating the required P:E (precipitation:evaporation) conditions (i.e., paleo hydroclimates) requisite for filling the lake. Using sediment cores collected in the 1980s, Well et al. (2003) produced a qualitative record of lake level change from 22.6ka 14C to 8.6ka 14C years. While an excellent initial study, the lake sediment cores are constrained by only six 14C dates on bulk organic matter. Using the Wells et al. (2003) study as a starting point, we collected over 62 m of new sediment cores in 2018, adjacent to the primary Wells et al. (2003) sediment core locations. Although still in progress, we now have acquired 23 x 14C dates from either bulk organic matter or ostracods spanning 23.8ka cal BP to 3.8ka cal BP. Using a Bayesian determined age model (Bacon v.2.2, IntCal13) on our 23 x 14C calibrated dates, we compare the ages of beach, or near-shoreline, indicators to the lake sediment core-based chronostratigraphic horizons. Using this basin analysis approach, we provide the first-ever, quantitative calculation of Lake Mojave minimum lake depth through time. We also explore future research directions for Lake Mojave using this basin analysis approach and its implications for hydroclimatic models.