PALEOTEMPERATURES PRESERVED IN FLUID INCLUSIONS IN HALITE

A variety of paleoclimate proxy records allow determination of relativ e warning or cooling. However, if we are to understand climate change, quantification of past temperature fluctuations is essential. Our res earch indicates that fluid inclusions in halite can yield homogenizati on temperatures that record surface brine temperatures at the time of halite precipitation. To avoid problems with stretching, leaking, and initial trapping of air, samples with primary, single phase (liquid) f luid inclusions are chilled in a freezer to nucleate vapor bubbles. We tested the reliability of this method of obtaining fluid-inclusion ho mogenization temperatures using modern salts precipitated at Badwater Basin, Death Valley, California. Homogenization temperatures correlate well with measured brine temperatures. The same method is applied to fluid inclusions in Pleistocene halite from a core taken at the same l ocation in Death Valley. Results are at several scales, recording diur nal temperature variations, seasonal temperature fluctuations, and lon ger-term warming and cooling events that correlate with major changes in the sedimentary environment related to climate. This technique is u niquely instrumental for paleoclimate studies because it offers actual , not just proxy, paleotemperature data.