COMPARATIVE FOSSILIZATION PROCESSES FROM THREE HYPERSALINE ENVIRONMENTS AND THE GEOLOGICAL IMPLICATIONS

Terrestrial biotas from microbially dominated hypersaline environments will help us understand fossilization processes, including the effects of pH, ion availability and seasonal changes. The three sites, Storr's Lake, San Salvador Island (Bahamas), Mono Lake (California), and the Dead Sea (Israel) represent both marine and nonmarine sites. Storr's Lake is a marine site, while the Dead Sea and Mono Lake are inland arid basins with respective elevations of 400 m below sea level, and 2100 m above sea level. Microscopically there was evidence of microbial activity at all sites, but macroscopically the sites were different. For instance, bulbous, stromatolites and thick, slimy biofilm deposits were found in Storrs Lake, Mono Lake had extensive tufa and benthic mats, but the Dead Sea lacked macroscopic signs of microbial activity. Continued deposition of microbial deposits at the three sites, and the enhanced precipitation of minerals associated with microbial fossilization will ultimately affect diagenesis and mineralogical composition of the rocks. For instance, elevated levels of Si and S identified within the Storrs Lake microbial samples, Si, Mg., Fe from Mono Lake, would not be available for recycling within the original aquatic system with the burial and subsequent lithification of fossilized microbes. Their accumulation over an extended geological period of time could indicate higher levels of these elements than were actually present in the depositional environment; hence the interpretation of the paleoenvironment may not reflect the original depositional environment.