THE RESEARCH OUTLINED IN THIS PROPOSAL IS DIRECTED TOWARDS UNDERSTANDING THE NATURE AND ORIGIN OF A VARIETY OF COMPONENTS IN CHONDRITIC METEORITES IN THE CONTEXT OF EARLY SOLAR NEBULAR AND PARENT BODY EVOLUTION. THE GOALS OF THE RESEARCH ARE TO UNRAVEL THE COMPLEX SEQUENCE OF EVENTS THAT PRODUCED THE CHEMICALLY AND MINERALOGICALLY DIVERSE ASSEMBLAGES OBSERVED IN PRIMITIVE METEORITES. WE WILL CARRY OUT MINERALOGICAL PETROLOGIC AND ISOTOPIC STUDIES USING A VARIETY OF MICROBEAM TECHNIQUES (SEM EPMA EBSD FIB/TEM NANOSIMS AND SXRF MICROPROBE) AS WELL AS STABLE ISOTOPE TECHNIQUES IN A COLLABORATIVE EFFORT WITH SEVERAL OTHER RESEARCH GROUPS. OUR PROPOSED STUDIES ARE DIVIDED INTO SIX SPECIFIC AREAS: 1) MINERALOGICAL AND TRACE ELEMENT STUDIES OF MATRICES IN PRIMITIVE CHONDRITES TO DEVELOP A FULLER UNDERSTANDING OF THE DIVERSITY OF COMPONENTS THEY CONTAIN AND THEIR ORIGINS 2) INTEGRATED NANOSIMS/FIB/TEM STUDIES OF PRESOLAR SILICATE GRAINS IN CR CARBONACEOUS CHONDRITES 3) MICROSTRUCTURAL AND TRACE ELEMENT STUDIES TOCONSTRAIN THE ORIGIN OF AMEBOID OLIVINE AGGREGATES IN CO3 CHONDRITES 4) EPMA AND TEM STUDIES OF METASOMATIC AND METAMORPHIC EFFECTS IN REFRACTORY INCLUSIONS IN CO3 CHONDRITES 5) MINERALOGICAL AND ISOTOPIC STUDIES OF AQUEOUS ALTERATION PROCESSES IN CR CHONDRITES AND 6) TEM AND TRACE ELEMENT STUDIES OF SULFIDES IN CM CHONDRITES TO CONSTRAIN THEIR FORMATIONAL AND THERMAL HISTORIES.