EARTH LIKE NUMEROUS OTHER PLANETS IN OUR SOLAR SYSTEM HAS EXPERIENCED NUMEROUS INTERVALS OF GLACIATION THROUGHOUT ITS HISTORY. ON EARTH ABUNDANT ACTIVE AND DIVERSE MICROBIOMES EXIST BENEATH ICE MASSES WHICH ARE SUPPORTED BY MINERAL BASED ENERGY MADE AVAILABLE THROUGH THE COMMUNITION OF BEDROCK. RECENT RESEARCH CONDUCTED ON ICE MASSES IN SEDIMENTARY AND METASEDIMENTARY CATCHMENTS INDICATE A PRIMARY ROLE FOR FE AND S IN MINERALS SUCH AS PYRITE IN SUSTAINING MICROBES IN A RANGE OF SUBGLACIAL ENVIRONMENTS DESPITE PYRITE ONLY BEING OF LOW ABUNDANCE 1 2 WT IN THE BEDROCK. HOWEVER LITTLE IS KNOWN OF THE ROLE OF MINERALOGYOR OF THE SPECIFIC WATER ROCK INTERACTIONS THAT SUSTAIN MICROBIAL ECOSYSTEMS IN GRANITIC OR BASALTIC SYSTEMS.CRUSHED BASALT WHICH COMPRISES 5 14 WT FEO AND 45 55 WT SIO2 HAS BEEN SHOWN TO GENERATE HYDROGEN H2 WHEN EXPOSED TO WATER AT 30 TO 60OC. THE H2 PRODUCED WAS SUGGESTED TO RESULT FROM THE REDUCTION OF WATER BY REDUCED IRON. HOWEVER RECENT RESEARCH BY THE AUTHORS DEMONSTRATES SIGNIFICANT H2 PRODUCTION FOLLOWING ABIOTIC CRUSHING OF A VARIETY OF SILICATE MINERALS AT 0OC AND SUBSEQUENT WETTING IN A PROCESS THAT SIMULATES GLACIAL COMMUNITION OF SILICATE BEDROCK. DESPITE ITS HIGH SI CONTENT BASALT WAS NOT ANALYZED IN OUR RECENT STUDY AND SO RATES OF ABIOTIC H2 RELEASE FROM CRUSHED WETTED BASALT VIA A SI MINERAL SHEARING MECHANISM AT TEMPERATURES RELEVANT TO SUBGLACIAL ECOSYSTEMS 0 1OC ARE UNKNOWN. MOREOVER IT IS UNCLEAR IF SI MINERAL SHEARING OR FE BASED MECHANISMS ARE MOST LIKELY TO CONTRIBUTE H2 IN BASALTIC SUBGLACIAL SYSTEMS AND WHETHER MICROBIAL COMMUNITIES PRESENT IN THESE SYSTEMS ARE FOUNDED ON H2 BASED CHEMOLITHOAUTOTROPHY. THIS LEADS TO OUR OVERARCHING HYPOTHESIS BASALT IN SUBGLACIAL SYSTEMS COMMINUTED BY GLACIAL GRINDING AND ABRASION LIBERATES H2 ABIOTICALLY WHICH SUSTAINS A DIVERSE AND ACTIVE H2 BASED CHEMOLITHOAUTOTROPHIC MICROBIAL COMMUNITY AT 0 1OC. OUR OVERARCHING OBJECTIVE IS TO INVESTIGATE THE PRODUCTION OF H2 IN SUBGLACIAL BASALTIC SYSTEMS AND ITS ROLE IN SUSTAINING CHEMOLITHOTROPHIC COMMUNITIES. SPECIFIC OBJECTIVES ARE TO 1. CHARACTERIZE THE CHEMISTRY OF MELTWATERS IN A RANGE GLACIAL CATCHMENTS IN ICELAND AND DETERMINE THE CAPACITY FOR SILICATE MINERAL SHEARING AND BASALT IRON TO GENERATE H2 2. DETERMINE RATES OF BIOLOGICALH2 TRANSFORMATION AND CO2 FIXATION IN SUBGLACIAL SEDIMENT COMMUNITIES 3. QUANTIFY ENRICHMENT IN H2 BASED METABOLISM ALONG GEOCHEMICAL GRADIENTS USING METAGENOMICS AND TARGETED TRANSCRIPTOMICS AND 4. MODEL THE RELATIONSHIPS BETWEEN ABIOTIC MECHANISMS OF H2 PRODUCTION PROCESS RATES AND GENETIC TRANSCRIPTIONAL DATA. THE INTEGRATION OF THE PROPOSED DATA WILL PROVIDE KEY NEW INSIGHTS INTO THE POTENTIAL FOR WATER ROCK INTERACTIONS IN SUPPORTING MICROBIAL LIFE IN COLD DARK SUBGLACIAL ENVIRONMENTS.THE PROPOSED RESEARCH IS RELEVANT TO SEVERAL ASPECTS OF NASAS EXOBIOLOGY PROGRAM INCLUDING EARLY EVOLUTION OF LIFE AND THE BIOSPHERE LARGE SCALE ENVIRONMENTAL CHANGE AND MACRO EVOLUTION AND BIOSIGNATURES AND LIFE ELSEWHERE. THE ADVANCE AND RETREAT OF ICE DURING GLACIAL INTERGLACIAL CYCLES THROUGHOUT EARTHS HISTORY IS THOUGHT TO HAVE DRIVEN LARGE SCALE SHIFTS IN THE DISTRIBUTION OF TAXA TO HABITATS WITH MORE STABLE CLIMATIC CONDITIONS REFUGIA ENABLING DIVERSE MICROBIAL ASSEMBLAGES TO PERSIST IN SUBGLACIALSEDIMENTS. AS EARTH HAS EXPERIENCED A NUMBER OF SNOWBALL EARTH EVENTS FINDINGS FROM THIS RESEARCH WILL PROVIDE KEY INSIGHTS INTO THE PREDOMINANT METABOLIC PROCESSES CAPABLE OF SUSTAINING EARTHS BIOSPHERE DURING WIDESPREAD GLACIATION AND ITS POTENTIAL IN DRIVING CHANGES IN MAJOR GEOCHEMICAL CYCLES. FINALLY MICROBIALLY DRIVEN SUBGLACIAL WEATHERING OF BASALTS IN TERRESTRIAL SYSTEMS MAY PRODUCE BIOSIGNATURES FE OXIDES THAT COULD BE RELEVANT FOR THE FORMATION AND RETENTION OF BIOSIGNATURES UNDER NON EARTH CONDITIONS GIVENTHE PRESENCE OF BASALT IN FORMERLY GLACIATED REGIONS ON MARS AND OTHER PLANETARY BODIES.