REINTERPRETATION OF CHLORINE-36 DEPTH PROFILES AND THE PALEOCLIMATE IMPLICATIONS OF SHORELINE DEPOSITS IN PANAMINT VALLEY, CA

Panamint Valley, California, is important for determining the paleoclimate of the western Great Basin. The valley held the fifth lake in a chain of six lakes that formed by overflow of the Owens River during Pleistocene pluvial episodes in the southwestern Great Basin. The chronology of filling events in Panamint Valley is of particular interest because it filled only during unusually wet conditions in the Pleistocene. We sampled three accretionary beach features, gravel lacustrine bars, for cosmogenic chlorine-36 profile dating. One site was on the east side of the valley at 627m, one was near the southwest end at 616m, and the third site is in the northern part of the southern Panamint basin. These beach features represent the most prominent shorelines at the elevation of the outlet channel to Death Valley (603m), indicating a formation during the last time that Owens River system filled completely. These profiles have been reinterpreted using the most recent CRONUS-Earth depth profile calculator. The results indicate that the last overflow of Panamint Valley was during marine oxygen isotope stage (MIS) 6. Evidence from other lakes in the Owens River system and Lake Lahontan show similar wet periods during the Last Glacial Maximum.