Lake Andrei; a Pliocene pluvial lake in Eureka Valley, eastern California

We used geologic mapping, tephrochronology, and (super 40) Ar/ (super 39) Ar dating to describe evidence of a ca. 3.5 Ma pluvial lake in Eureka Valley, eastern California, that we informally name herein Lake Andrei. We identified six different tuffs in the Eureka Valley drainage basin, including two previously undescribed tuffs: the 3.509+ or -0.009 Ma tuff of Hanging Rock Canyon and the 3.506+ or -0.010 Ma tuff of Last Chance (informal names). We focused on four Pliocene stratigraphic sequences. Three sequences are composed of fluvial sandstone and conglomerate, with basalt flows in two of these sequences. The fourth sequence, located approximately 1.5 km south of the Death Valley/Big Pine Road along the western piedmont of the Last Chance Range, included green, fine-grained, gypsiferous lacustrine deposits interbedded with the 3.506 Ma tuff of Last Chance that we interpret as evidence of a pluvial lake. Pluvial Lake Andrei is similar in age to pluvial lakes in Searles Valley, Amargosa Valley, Fish Lake Valley, and Death Valley of the western Great Basin. We interpret these simultaneous lakes in the region as indirect evidence of a significant glacial climate in western North America during marine isotope stages Mammoth/Gilbert 5 to Mammoth 2 (MIS MG5/M2) and a persistent Pacific jet stream south of 37 degrees N.