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Paper No. 111-7
Presentation Time: 8:00 AM-5:30 PM
EVIDENCE FOR A LAKE LEVEL LOW STAND DURING HEINRICH STADIAL 1 AT LAKE MOJAVE(SILVER LAKE, CA)
It is essential to understand how hydroclimatic changes occurred in the past to inform future water management practices. This is especially important for arid environments such as the Mojave Desert, where water resources are limited. Existing paleoclimatic research reveals that Silver Lake playa was once occupied by a significantly larger, deeper predecessor known as Lake Mojave between ca 24.5 ka and the early Holocene. This study focuses on Lake Mojave’s hydroclimatic history during the latter half of the Heinrich Stadial 1 (HS-1, ~15.4-17.7 ka). Heinrich stadial 1 is associated with a massive discharge of ice and meltwater into the North Atlantic, heavily altering ocean-atmosphere dynamics, resulting in significant changes to the Northern Hemisphere’s hydroclimate. During HS-1, the Mojave Desert experienced generally wetter conditions, likely associated with more snowpack (runoff) in the San Bernardino Mountains and more frequent winter storms. However, the range of changes in lake depth during HS-1 is poorly constrained for Lake Mojave, due to limited age control and quantitative sediment analysis. In this paper, changes in grain size from a well-dated sediment core (SLDC18-1) are used to infer relative lake depth during the latter half of HS-1. Here, we focus on changes in percent clay and medium sand/coarse sand as proxies for lake depth and runoff, respectively. Grain size results suggest large amplitude changes in lake depth and runoff between ~15.4-17.7 ka. Within this period, there is a pronounced lake depth low stand between 16.6 and 16.3 ka. This low stand is bracketed between periods of generally deeper but variable water depths and runoff. Regionally, this low stand is correlative to a period of reduced runoff as inferred from sand content in Lake Elsinore (approximately 218 km south-southwest of Silver Lake). This broad correlation between two distal sites suggests a common forcing for this HS-1 low stand event.