Paleobiotic and isotopic analysis of mollusks, fish and plants from core OL-92: Indicators for an open or closed lake system

Intervals of open versus closed lake systems for Pleistocene Owens Lake in California are suggested by a comparison of paleobiotic and isotopic evidence recovered from core samples of OL-92. Mollusks and fish were identified from 67 core samples, and their ecological requirements were noted. Carbon dioxide extractions for stable isotopes of ¹³C and ¹⁸O from aragonite of the molluscan shell material were obtained by standard procedures, and isotopic compositions were measured using a mass spectrometer. The values of ¹³C and ¹⁸O from sediment samples taken previously (Benson and Bischoff, 1993) were compared with ¹³C and ¹⁸O values from mollusk shells recovered from the core. These data indicate at least two times of open lake, very low salinity (or “fresh” water) episodes, which are in agreement with the interpretation of fish and mollusk paleoecology supporting open systems between 207 m and 208 m (ca. 450 ka to ca. 453 ka) and between 309 m and 313 m (ca. 765 ka to ca. 775 ka).