CERES IS THE LARGEST BODY IN THE MAIN ASTEROID BELT WITH A UNIQUE SURFACE COMPOSITION AND A LOW-DENSITY INTERIOR STRUCTURE. INITIAL DAWN RESULTS REVEAL AMMONIATED AND MG PHYLLOSILICATES AND MG-CA CARBONATES IN SURFACE MATERIALS. BRIGHT DEPOSITS IN OCCATOR CRATER ARE RICH IN NA CARBONATE AND MAY CONTAIN AMMONIATED SALTS. THESE MINERAL ASSEMBLAGES ARE ATYPICAL FOR SOLID PLANETS AND METEORITES AND MAY INDICATE UNCOMMON AQUEOUS PROCESSES WITH MUCH CO2 AND AMMONIA WHICH ARE ONLY ABUNDANT IN THE OUTER SOLAR SYSTEM. DAWN GRAVITY DATA INDICATE A CONCENTRATION OF MASS IN THE DEEP INTERIOR AND MAY INDICATE AT LEAST SOME WATER-ROCK SEPARATION IN THE HISTORY OF THE BODY. THESE OBSERVATIONS COULD CONSTRAIN THE FORMATION AND SUBSEQUENT HISTORY OF CERES AND ANALOGUES BODIES IF MINERALFORMING CONDITIONS ARE UNDERSTOOD.OBJECTIVES. OUR GOAL IS TO CONSTRAIN FORMATION CONDITIONS OF VOLATILE-BEARING AND WATER-DEPOSITED MINERALS ON CERES (CARBONATES OTHER SALTS AMMONIATED AND OTHER PHYLLOSILICATES OXIDES AND S-BEARING PHASES) THROUGH NUMERICAL GEOCHEMICAL MODELING OF WATER-ROCK-GAS AND WATER-SALT TYPE SYSTEMS. (1) WE WILL CONSTRAIN THE FUNDAMENTAL CHEMISTRY AND MINERALOGY OF WATER-ROCK INTERACTION IN CO2- AND NH3-RICH SYSTEMS AS FUNCTIONS OF TEMPERATURE PRESSURE AND WATER/ROCK/CO2/NH3 MASS RATIOS. (2) WE WILL CONSIDER PHYSICAL CHEMISTRY OF WATER-ROCK INTERACTIONS IN THE INTERIOR OF CERES FOR STATIC AND FLUID TRANSFER CASES. THIS WORK WILL CONSTRAIN CHEMICAL AND DENSITY PROFILES TOGETHER WITH THE COMPOSITION OF ALTERED ROCKS AND RELEASED FLUIDS. (3) WE WILL MODEL POST-IMPACT SUBSURFACE AQUEOUS CHEMICAL PROCESSES TO CONSTRAIN ORIGINS OF SECONDARY MINERALS ESPECIALLY IN SALT-RICH BRIGHT DEPOSITS. METHODOLOGY. THE SPECIATION OF WATER-ROCK-GAS AND WATER-SALT TYPE SYSTEMS WILL BE EVALUATED THROUGH CALCULATIONS OF CHEMICAL EQUILIBRIA CONSTRAINED BY MASS BALANCES AT SPECIFIED TEMPERATURES AND PRESSURE IN THE DEEP AND SHALLOW INTERIOR. BOTH HYDROTHERMAL AND SUBFREEZING CONDITIONS WILL BE CONSIDERED. WE WILL CALCULATE COMPOSITIONS AND DENSITIES OF ALTERED ROCKS AND PRECIPITATED SALTS TOGETHER WITH CONCENTRATIONS AND ACTIVITIES OF SPECIES IN AQUEOUS SOLUTIONS. ACID-BASE AND REDUCTION-OXIDATION CONDITIONS WILL BE EVALUATED FOR FORMING FLUIDS. BOTH STATIC (ISOCHEMICAL) AND MOBILE SYSTEMS WILL BE MODELED. THE FLUID TRANSFER WILL BE CONSIDERED FOR THE INTERIOR DEHYDRATION SCENARIOS AND POST-IMPACT AQUEOUS SYSTEMS. DAWN GRAVITY AND SHAPE DATA WILL BE USED TO CONSTRAIN THE COUPLED INTERIOR STRUCTURE AND COMPOSITION OF THE BODY. THE RESULTS WILL BE INTERPRETED IN TERMS OF GEOLOGICAL AND PHYSICAL-CHEMICAL PROCESSES AND COMPOSITION OF OBSERVABLE MATERIALS. THIS WORK IS A CONTINUATION OF THE ONGOING EFFORTS OF THE PI TO CONSTRAIN ORIGINS OF MINERALS ON CERES AND OTHER SOLAR SYSTEM BODIES. IMPORTANCE AND RELEVANCE. THE PROPOSED WORK WILL ASSESS FORMATION CONDITIONS OF UNUSUAL ASSEMBLAGES OF AQUEOUS MINERALS ON CERES. IT WILL CONSTRAIN AQUEOUS ENVIRONMENTS ON CERES AND ANALOGUES NH3-CO2 RICH BODIES IN THE OUTER SOLAR SYSTEM (KBOS SOME ICY MOONS AND COMETS). THE WORK WILL REVEAL CHEMICAL TRANSFORMATIONS MASS TRANSFER AND DENSITY CHANGE CAUSED BY INTERIOR AQUEOUS PROCESSES AND FORMATION OF PUTATIVE WATER MANTLE. THE PROPOSAL IS RELEVANT TO THE SSW PROGRAM BECAUSE IT IS INTENDED TO UNDERSTAND THE CHEMICAL AND MINERALOGICAL FEATURES OF PLANETARY SURFACES AND FLUID INVENTORIES. THE WORK IS AIMED AT RECONSTRUCTING THE HISTORY OF VOLATILE INVENTORIES AND UNDERSTANDING THE PHYSICAL-CHEMICAL PROCESSES THAT AFFECT THEM. THE PROPOSED WORK WILL DEVELOP THEORETICAL BASES FOR UNDERSTANDING MINERALOGICAL FEATURES. THE WORK WILL USE NUMERICAL MODELING TO EXPLORE CHEMICAL PROCESSES WITHIN THE SOLAR SYSTEM.