PROPOSED RESEARCH WILL INVESTIGATE ALTERATION PROCESSES AFFECTING THE ISOTOPIC AND ELEMENTAL COMPOSITION OF WATER AND INSOLUBLE ORGANIC MATTER (IOM) IN CHONDRITE PARENT BODIES. SPECIFICALLY, EXPERIMENTS WILL BE CONDUCTED TO CONSTRAIN: (1) THE KINETICS OF MURCHISON IOM MODIFICATION (H/C, N/C) AND IOM-WATER H ISOTOPE EXCHANGE UNDER HYDROTHERMAL CONDITIONS AS A FUNCTION OF PH AND DOWN TO LOWER TEMPERATURES (150-300 OC) THAN IN PREVIOUS STUDIES (2) THE ELEMENTAL/ISOTOPIC RESPONSE OF CR IOM AT SIMILAR HYDROTHERMAL CONDITIONS TO DETERMINE IF ALL C1/2 IOM COULD HAVE A COMMON CR-LIKE PRECURSOR (3) THE KINETICS OF D/H EXCHANGE AT THE MOLECULAR LEVEL OF THE FUNCTIONAL GROUPS IN ANALOG IOM (SYN-IOM) AND (4) THE VARIATION IN O/C AND O ISOTOPE SYSTEMATICS BETWEEN HYDROTHERMALLY ALTERED CHONDRITIC/SYN-IOM AND H2O. THE AIM OF THE PROPOSAL IS TO DEVELOP A DETAILED UNDERSTANDING OF HOW THE ELEMENTAL/ISOTOPIC COMPOSITION AND STRUCTURE OF IOM IN CHONDRITES WAS MODIFIED BY METAMORPHISM AND AQUEOUS ALTERATION IN THE CHONDRITE PARENT BODIES. EXPERIMENTAL RESULTS WILL SHED LIGHT ON THE ISOTOPIC EVOLUTION OF CHONDRITES AFTER ACCRETION, AND THE ORIGINS OF THE H2O AND ORGANICS ACCRETED, THE THERMAL HISTORIES OF AQUEOUSLY ALTERED AND MILDLY METAMORPHOSED CHONDRITES.