EARLY SOLAR SYSTEM MATERIALS: CHEMICAL PETROLOGIC AND ISOTOPIC INVESTIGATIONS:THE PROPOSED RESEARCH INTEGRATES PETROLOGIC CHEMICAL AND ISOTOPIC STUDIES OF CHONDRITIC METEORITES WITH THE OBJECTIVE OF UNDERSTANDING PROCESSES THAT TOOK PLACE IN THE EARLY SOLAR SYSTEM. EXPERIMENTAL STUDIES ARE DESIGNED TO COMPLEMENT INVESTIGATIONS OF NATURAL SAMPLES. WE AIM TO UNDERSTAND THE PROCESSES RESPONSIBLE FOR PRODUCING THE WIDE DIVERSITY OF CHONDRULE PROPERTIES BOTH WITHIN AND AMONG CHONDRITE GROUPS TO STUDY RELATIONSHIPS BETWEEN VARIOUS CHONDRITE COMPONENTS AND TO RECONCILE THE DIVERSE THERMAL HISTORIES THAT ARE RECORDED BY DIFFERENT COMPONENTS IN THE SAME CHONDRITES. WE ARE ALSO INVESTIGATING THE EARLY GEOLOGICAL HISTORY OF CHONDRITIC ASTEROIDS THROUGH THE RECORD OF METAMORPHISM. RESEARCH TASKS PROPOSED INCLUDE: 1) UNDERSTANDING THE DIVERSITY OF CHONDRULE CHEMICAL COMPOSITIONS AND THE NATURE OF CHONDRULE PRECURSORS; 2) OXYGEN ISOTOPIC CHARACTERIZATION OF CHONDRULES FROM A VARIETY OF CHONDRITE GROUPS; 3) STUDIES OF THE FORMATION AND ALTERATION OF PRIMARY PLAGIOCLASE IN CHONDRULES 4) INVESTIGATING THE NATURE OF VOLATILITY-CONTROLLED CHEMICAL FRACTIONATIONS IN EARLY SOLAR SYSTEM MATERIALS; 5) INTERPRETING THERMAL HISTORIES OF CHONDRITE COMPONENTS THROUGH STUDIES OF METAL MICROSTRUCTURES; 6) OBSERVATIONS AND EXPERIMENTAL STUDIES OF SOLID-STATE REDUCTION REACTIONS IN SILICATE MINERALS; 7) INVESTIGATING PARENT BODY METAMORPHISM BY EXAMINING SECONDARY MINERALS. WE EMPHASIZE MICROBEAM ANALYTICAL TECHNIQUES BOTH IN HOUSE AND IN COLLABORATION WITH OTHER LABORATORIES. OPTICAL MICROSCOPY SCANNING ELECTRON MICROSCOPY (SEM) ELECTRON MICROPROBE ANALYSIS (EPMA) AND TRANSMISSION ELECTRON MICROSCOPY (TEM) ARE USED FOR PETROGRAPHY AND MINERAL ANALYSES. SAMPLE PREPARATION FOR TEM WILL BE ACCOMPLISHED USING FOCUSED ION BEAM (FIB) TECHNIQUES. SECONDARY ION MASS SPECTROMETRY (SIMS) AND LASER-ABLATION INDUCTIVELY-COUPLED-PLASMA MASS-SPECTROMETRY (LA-ICP-MS) ARE USED FOR MEASUREMENTS OF TRACE ELEMENTS. OXYGEN ISOTOPE CHARACTERIZATION OF CHONDRITE COMPONENTS IS CARRIED OUT WITH A COMBINATION OF SIMS MEASUREMENTS FOR MINERAL PHASES IN SITU AND LASER FLUROINATION MASS SPECTROMETRY FOR DISAGGREGATED SAMPLES. EXPERIMENTAL STUDIES WILL BE MADE AT ONE-ATMOSPHERE WITH CONTROLLED TEMPERATURE AND OXYGEN FUGACITY.