SULFATES ARE MAJOR SECONDARY MINERALS ON THE MARTIAN SURFACE FROM THE EQUATOR TO THE POLAR REGIONS ON MARS TYPICALLY FOUND AS CONCENTRATED DEPOSITS IN LAYERED SEDIMENTARY ROCKS AND ARE AT LOW LEVELS IN SOILS ACROSS MUCH OF THE SURFACE. THESE OCCURRENCES SUGGEST THAT SULFUR CYCLE MAY HAVE BEEN THE PREDOMINANT WEATHERING AGENT ON MARS POTENTIALLY PEAKING IN THE HESPERIAN AGE WHEN MOST OF THE MAJOR SULFATE DEPOSITS HAVE BEEN DATED. SOME OF THE MAJOR FORMS OF SULFATES ON MARS ARE GYPSUM/ANHYDRITE JAROSITE AND ALUNITE MINERAL TYPES THAT ARE WIDELY SPREAD ON EARTH. SULFATE MULTIPLE ISOTOPE SYSTEMATICS ARE DIAGNOSTIC AND HELP DISCRIMINATE SULFATE FORMATION MECHANISMS THROUGHOUT EARTH HISTORY. SIMILARLY MARTIAN SULFATES ALSO CONTAIN A WEALTH OF INFORMATION ABOUT THE PHYSIOCHEMICAL CONDITIONS OF THEIR FORMATION TIME AND LOCATION. SPECIFICALLY THEIR TRIPLE OXYGEN ISOTOPE COMPOSITIONS WILL HELP CONSTRAIN THE INTENSITY OF INTERACTION BETWEEN OXYGEN RESERVOIRS IN THE ATMOSPHERE HYDROSPHERE AND LITHOSPHERE. ON MARS INTRIGUING OXYGEN HETEROGENEITY HAS BEEN OBSERVED AMONGST THOSE RESERVOIRS AND REMAINS UNEXPLAINED. SULFATE MINERALS ARE PRESENT IN VARIOUS MARTIAN METEORITES AND THESE SAMPLES PROVIDE AN EXCELLENT OPPORTUNITY TO EXTRACT INFORMATION REGARDING THE MARTIAN PALEO-CLIMATE SURFACE AND ATMOSPHERE REDOX CONDITION AND POTENTIAL BIOLOGICAL PROCESSES. WE PROPOSE TO PERFORM A COMPREHENSIVE PETROGRAPHIC ISOTOPIC AND MODELING STUDY FOCUSING ON BOTH MARTIAN METEORITES AND ORDINARY CHONDRITES (OCS) COLLECTED FROM ANTARCTICA. THIS STUDY WILL EXPLORE SULFATE FORMATION MECHANISMS ON MARS AND POTENTIAL ANTARCTIC SULFATE FORMATION MECHANISMS IN METEORITES ON EARTH. THE OBJECTIVES OF THIS PROJECT INCLUDE: 1) IDENTIFICATIONS OF SULFATE MINERALS WITHIN THE BULK METEORITE SAMPLES USING PETROGRAPHY AND BULK EXTRACTIONS; 2) CHARACTERIZATION OF TERRESTRIAL WEATHERING PRODUCTS FOUND IN ANTARCTIC METEORITES (OCS) FROM LOCALITIES WHERE MARTIAN METEORITES WERE FOUND; 3) EVALUATION OF THE INDIGENOUS SULFATE MINERALS FROM MARTIAN METEORITE (SHERGOTTITES AND NAKHLITES) AND ESTABLISH THEIR ISOTOPE SIGNATURES (MAINLY OXYGEN ISOTOPES) BASED ON 3); 4) DEVELOPMENT OF CONCEPTUAL MODEL TO INTERPRET THE SULFUR CYCLE AND OXYGEN EXCHANGE IN THE MARTIAN ATMOSPHERE-HYDROSPHERELITHOSPHERE- MANTLE SYSTEM. THE OBJECTIVES WILL BE ACCOMPLISHED BY ANALYTICAL MEANS USING: SCANNING ELECTRON MICROSCOPE AND X-RAY DIFFRACTION ANALYSIS FOR MINERAL IDENTIFICATIONS OF SULFATES WITHIN METEORITE BODY SEQUENTIAL EXTRACTION OF SULFATE PHASES BASED ON THEIR STABILITIES IN SOLUTION ACCOMPANIED BY CORRESPONDING ION EXAMINATIONS OF EACH EXTRACT VIA INDUCTIVELY COUPLED PLASMA-MASS SPECTROMETRY TRIPLE OXYGEN ISOTOPE (CAPDELTA 17O) AND QUADRUPLE SULFUR (CAPDELTA 33 36S) ANALYSIS VIA LASER FLUORINATION TECHNIQUE AND SUBSEQUENT MEASUREMENT ON DUAL-INLET GAS PHASE MASS SPECTROMETER AND FINALLY OXYGEN/SULFUR (DELTA18O AND DELTA34S) ISOTOPE ANALYSIS VIA ELEMENTAL ANALYZER-MASS SPECTROMETER. THE HIGH RESOLUTION STABLE ISOTOPE ANALYSIS COORDINATED WITH CORRESPONDING MINERAL IDENTIFICATION AND SEPARATION WILL ENABLE US TO DIFFERENTIATE SULFATE MINERAL FORMATION MECHANISMS AND THEIR LINKS TO MAGMATIC ACTIVITY HYDROTHERMAL SYSTEMS SURFACE WEATHERING AND ATMOSPHERIC CHEMISTRY. THE RESEARCH PROPOSAL IS HIGHLY RELEVANT TO THE SOLAR SYSTEM WORKINGS PROGRAM WHICH SUPPORTS RESEARCH PROJECTS ON UNDERSTANDING THE ATMOSPHERIC CLIMATOLOGICAL DYNAMICAL GEOLOGIC PHYSICAL AND CHEMICAL PROCESSES OCCURRING WITHIN THE SOLAR SYSTEM EXPLICITLY ON PLANETARY BODIES. THE MAIN GOAL OF THIS RESEARCH PROJECT IS TO UNDERSTAND THE MARTIAN ATMOSPHERE EVOLUTION AND ELEMENTAL CYCLING BETWEEN ATMOSPHERE HYDROSPHERE AND LITHOSPHERE WHICH IS WELL WITHIN THE PROGRAM THEME. OUR STUDY WILL ALSO PROVIDE INSIGHTS INTO THE LOW WATER/ROCK RATIO SULFUR WEATHERING PROCESSES BY STUDYING OBJECTS FROM MARTIAN ANALOG ANTARCTIC CONTINENT. THIS PROJECT DOES NOT INVOLVE ANY MARTIAN MISSION RELATED DATA ANALYSIS.