THE ENSTATITE CHONDRITES ARE IMPORTANT FOR UNDERSTANDING THE EVOLUTION OF THE INNER SOLAR SYSTEM. THEY HAVE STABLE ISOTOPE COMPOSITIONS SIMILAR TO THE EARTH AND MOON SUGGESTING A GENETIC RELATIONSHIP AND MAY BE ANALOGUES OF THE PRIMITIVE MATERIALS THAT ACCRETED TO FORM THE EARTH OR ARE POSSIBLY PRODUCTS OF THE EVENT THAT FORMED EARTH S MOON. THE ENSTATITE CHONDRITES ARE EXTREMES IN THE CONDITIONS THAT RESULTED IN THE PROPERTIES OF PRIMITIVE METEORITES HAVING MINERAL ASSEMBLAGES THAT SUGGEST HIGHLY REDUCING CONDITIONS. THEIR CONSTITUENT COMPONENTS (CHONDRULES METAL SULFIDES MATRIX) ARE MARKEDLY DIFFERENT FROM THOSE OF ANY OTHER CHONDRITE GROUPS. THE ORIGIN OF EH3 AND EL3 ENSTATITE CHONDRITES AND THEIR COMPONENTS IS HIGHLY CONTROVERSIAL AND THE SOLAR SYSTEM ENVIRONMENT IN WHICH THEIR UNUSUAL PROPERTIES DEVELOPED IS POORLY UNDERSTOOD. EL3 CHONDRITES AND THEIR COMPONENTS HAVE BEEN INTERPRETED TO BE THE RESULT OF BRECCIATION AND IMPACT MELTING AND THEY HAVE ALSO BEEN INTERPRETED TO BE PRIMITIVE SOLAR SYSTEM MATERIALS. THE PROPOSED RESEARCH IS FOCUSED ON THE ORIGIN AND EVOLUTION OF ENSTATITE (EH3 AND EL3) CHONDRITES AND THE PLANNED ANALYSES ARE TARGETED AT TESTING HYPOTHESES FOR THE ORIGIN OF THEIR COMPONENTS (CHONDRULES FRAGMENTS METAL-RICH NODULES AND MATRIX) AND RELATIONSHIP TO OTHER CHONDRITE GROUPS AND EARTH-MOON. THE PI S GOALS ARE TO (1) DECIPHER THE PRE-ACCRETIONARY AND ASTEROIDAL EVOLUTION OF ENSTATITE (E) CHONDRITES (2) EVALUATE THE THERMAL HISTORIES OF E CHONDRITES DETERMINE WHICH ONES ARE THE MOST PRIMITIVE AND ESTABLISH PETROLOGIC (METAMORPHIC) GRADES FOR EH3 AND EL3 CHONDRITES (3) UNRAVEL AGE RELATIONSHIPS OF E CHONDRITE COMPONENTS (4) UNDERSTAND THE RELATIONSHIP BETWEEN EH AND EL CHONDRITES AND THEIR PARENT ASTEROIDS (5) ASSESS THE ROLE OF IMPACT IN THE EVOLUTION OF E CHONDRITES THEIR COMPONENTS AND PARENT ASTEROIDS. THE PI PROPOSES A PROGRAM THAT WILL INCLUDE PETROLOGICGEOCHEMICAL CONSORTIUM STUDIES EMPLOYING A VARIETY OF ANALYTICAL TECHNIQUES. FIVE CLOSELY RELATED TASKS TARGETED AT EVALUATING THE ORIGIN OF CHONDRULES MATRIX AND METAL-RICH NODULES IN ENSTATITE CHONDRITES ARE PROPOSED. THESE INCLUDE: (1) PETROLOGY AND MICRO-DISTRIBUTION OF OXYGEN ISOTOPES IN ALH 81189 A PRIMITIVE EH3 CHONDRITE (2) PETROLOGIC AND ISOTOPIC STUDY OF CHONDRULES IN THE EL3 CHONDRITES. (3) AGE RELATIONSHIPS (26AL CHRONOLOGY) OF CHONDRULES IN EH3 AND EL3 CHONDRITES. (4) PETROLOGIC TRACE ELEMENT AND ISOTOPIC STUDIES OF METAL-RICH NODULES IN EL3 CHONDRITES AND (5) STUDY OF MATRIX AND INSOLUBLE ORGANIC MATTER (IOM) IN EH3 AND EL3 CHONDRITES.

Research Foundation Of The City University Of New York, New York NY

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