PALEOTEMPERATURES FROM FLUID INCLUSIONS IN HALITE - METHOD VERIFICATION AND A 100,000-YEAR PALEOTEMPERATURE RECORD, DEATH-VALLEY, CA

Maximum homogenization temperatures of fluid inclusions (Th-max) in ha lite (laboratory-grown crystals and modern samples, Death Valley, CA) match maximum brine temperatures during halite precipitation. Maximum brine temperatures during halite precipitation in Death Valley, late A pril, 1993 (34.4 degrees C) agree with Th-max (34 degrees C) and corre late well with average maximum air temperatures in April (31.3 degrees C) and May (37.6 degrees C). Th-max may be used for paleoclimate inte rpretations based on the close relationship between saline lake temper atures and average air temperatures from modem settings. Lower homogen ization temperatures, demonstrably below the temperatures at which hal ite grew, are interpreted to reflect collapse of some fluid inclusion walls due to the pressure difference between the inside and outside of inclusions. By only using Th-max, the problems of anomalously low hom ogenization temperatures due to possible collapse of fluid inclusions are avoided. Halite samples from 30 stratigraphic intervals, 90 to 0 m (100 to 0 ka), Core DV93-1, Death Valley, CA, were used to measure ho mogenization temperatures of fluid inclusions. Virtually dl homogeniza tion temperatures from Core DV93-1 are below the modem Th,, of 34 degr ees C (halite precipitation late April, 1993). Lacustrine halites, dep osited in a perennial saline lake 35 to 10 ka, have Th-max between 19 degrees C and 30 degrees C, which suggests brine temperatures approxim ately 4 degrees C to 15 degrees C below modern late April values. Ephe meral saline lake halites precipitated 60 to 35 ka have Th-max between 23 degrees C and 28 degrees C, 6 to 11 degrees C below modern values. The highest Th-max value in the 100 ka record (up to 35 degrees C) is from a halite sample formed approximately 100 ka in a climate regime somewhat colder than the modern. (C) 1998 Elsevier Science B.V. All ri ghts reserved.