SCIENCE GOALS AND OBJECTIVES. MANY SEDIMENTS AND SEDIMENTARY ROCKS ON MARS HAVE SIMILAR MINERAL ASSEMBLAGES SEDIMENTARY CHARACTERISTICS AND DIAGENETIC FEATURES AS MODERN AND ANCIENT RED BED AND EVAPORITE SEQUENCES ON EARTH. ACID BRINE LAKE SYSTEMS ON CRATONIC ROCKS IN WESTERN AUSTRALIA AND AT AN ACTIVE VOLCANIC COMPLEX IN NORTHERN CHILE HAVE PHS AS LOW AS 1.4 SALINITIES UP TO 10 TIMES SALTIER THAN SEAWATER COMPLEX AQUEOUS COMPOSITIONS AND PRECIPITATE HALITE GYPSUM IRON OXIDES ALUNITE JAROSITE OPALLINE SILICA AND CLAY MINERALS. DESPITE EXTREME CHEMISTRY AND LOW WATER ACTIVITY RECENT AND ONGOING STUDIES HAVE DOCUMENTED DIVERSE COMMUNITIES OF EXTREMOPHILIC MICROORGANISMS MANY OF WHICH ARE NOVEL LIVING IN THESE ACID BRINE LAKE WATERS AND GROUNDWATERS. ARE THESE MICROORGANISMS PRESERVED IN THE MINERAL AND ROCK RECORD HERE? PRELIMINARY INVESTIGATION SUGGESTS THAT THE RAPID GROWTH OF MINERALS FROM ACID BRINES CAUSES HALITE AND GYPSUM TO TRAP MICROORGANISMS AND ORGANIC COMPOUNDS AS SOLID INCLUSIONS AND WITHIN FLUID INCLUSIONS. HOWEVER FURTHER STUDY IS NEEDED TO FULLY IDENTIFY THE MODES OF PRESERVATION OF BIOLOGICAL MATERIAL AS WELL AS TEST AND REFINE DETECTION METHODS. THE PRIMARY GOAL OF THIS PROPOSED RESEARCH IS TO USE MICROSCOPY AND SPECTROSCOPY TO CHARACTERIZE THE MICROBIAL COMMUNITY PRESERVED WITHIN HALITE AND GYPSUM FROM MODERN ACID BRINE LAKES IN WESTERN AUSTRALIA AND CHILE. SECONDARY GOALS OF THE PROJECT INCLUDE: (1) INVESTIGATING PERMO-TRIASSIC (~250 MA) ACID LAKE HALITE AND GYPSUM FOR ANY PRESERVED MICROORGANISMS AND/OR ORGANIC COMPOUNDS; (2) DOCUMENTING THE PRESERVATION MODE IN RELATION TO IN SITU OR REWORKED HALITE AND/OR GYPSUM AS WELL AS THE ROLE OF ASSOCIATED IRON OXIDE AND/OR CLAY MINERAL COATINGS; AND (3) COMPARING BIOLOGICAL MATTER IN MODERN AND ANCIENT ACID LAKE HALITE AND GYPSUM TO EVALUATE WHETHER MICROBES AND ORGANIC COMPOUNDS CAN REMAIN PRESERVED THROUGH DEEP TIME. METHODOLOGY. THIS PROPOSED RESEARCH IS BUILT ON THE FOUNDATION OF A LONG-TERM AND COMPREHENSIVE STUDY OF ACID SALINE LAKES AND ASSOCIATED ENVIRONMENTS. PI BENISON HAS EXPERTISE IN GEOLOGY GEOCHEMISTRY AND GEOMICROBIOLOGY OF ACID BRINE LAKE AND GROUNDWATER ENVIRONMENTS INCLUDING STUDY OF OVER 60 SALT LAKES IN SOUTHERN WESTERN AUSTRALIA AND TWO SALARS IN NORTHERN CHILE. FUNDING IS REQUESTED FOR A TWO-YEAR PROJECT TO SUPPORT LABORATORY ANALYSES OF MODERN HALITE AND GYPSUM PREVIOUSLY COLLECTED FROM WESTERN AUSTRALIA AND CHILE AS WELL AS ON PERMIAN AND TRIASSIC ACID LAKE HALITE IN PREVIOUSLY SAMPLED CORES FROM THE SUBSURFACE OF KANSAS AND NORTHERN IRELAND. WE PLAN TO: (1) CONDUCT PETROGRAPHIC INVESTIGATIONS USING TRANSMITTED REFLECTED POLARIZED AND UV VISIBLE LIGHT SOURCES AT 6.3 - 2000 X MAGNIFICATION TO DOCUMENT OPTICAL PROPERTIES OF SUSPECT MICROORGANISMS AND ORGANIC COMPOUNDS; (2) USE LASER RAMAN SPECTROSCOPY TO IDENTIFY CHEMICAL COMPOSITIONS OF ORGANIC MATERIAL FOUND WITH MICROSCOPY; AND (3) TEST THE FEASIBILITY OF IMAGING ORGANIC MATERIAL IN HALITE AND GYPSUM AS WELL AS IN ASSOCIATED SILICICLASTICS WITH SCANNING ELECTRON MICROSCOPY.