Late Quaternary paleohydrology of desert wetlands and pluvial lakes in the Soda Lake basin, central Mojave Desert, California (USA)

Abstract

Sediment cores taken near extant springs along the western margin of Soda Lake playa, as well as from the playa center, reveal dramatic hydrologic changes that occurred in the central Mojave Desert during the late Quaternary. Results of stratigraphic, chronologic, physical, chemical, and microfossil analyses of seven cores, ranging in length from 5 to 23 m, help refine the timing and character of the final stages of pluvial Lake Mojave during the late Pleistocene and define distinct periods of wetland development in the early and late Holocene. Evidence shows that an incipient lake occupied the central Soda Lake basin by at least 25.0 ka (ka = thousands of calibrated 14C years before present), and a fully developed Lake Mojave was present between 20.5 and 12.8 ka, before receding and ultimately yielding to playa conditions by 11.0 ka. Organic-rich “black mats” appear in several cores along the playa margin between 10.7 and 9.0 ka, suggesting that spring-fed wetlands persisted in this area long after the lake had regressed. The basin remained relatively dry throughout most of the Holocene until wetland ecosystems expanded along the margins between 0.73 and 0.18 ka, coincident with part of the Medieval Climate Anomaly and Little Ice Age. Overall, our results demonstrate that buried sediments surrounding extant and extinct springs can be used to reconstruct past hydrologic conditions in desert environments on a variety of spatial and temporal scales, and provide important baseline information for effective management of limited desert resources.