Project Grant NNX11AG65G

ANGRITES ARE ANCIENT BASALTIC METEORITES (~4.56 GA) THAT PRESERVE SOME EVIDENCE OF THE SOLAR SYSTEM'S EARLIEST DIFFERENTIATION EVENTS. THE VOLCANIC-TEXTURED ANGRITES WERE RAPIDLY CRYSTALLIZED AND ARE RELATIVELY PRISTINE. THUS THESE ANGRITES PROVIDE A UNIQUE "WINDOW" INTO THE PETROGENESIS OF PLANETARY BODIES IN THE EARLY SOLAR SYSTEM WHICH IS NEEDED TO RECONSTRUCT THE EARLIEST STAGES OF PLANETESIMAL ACCRETION AND EVOLUTION AND TO UNDERSTAND THE INITIAL COMPOSITION OF THE TERRESTRIAL PLANETS. THIS PROPOSAL SEEKS TO EVALUATE THE PETROGENESIS OF ANGRITES CONCENTRATING ON THE INTENSIVE PARAMETERS AND PHYSICAL CONDITIONS OF THEIR FORMATION AND TO LINK THEIR PETROGRAPHY WITH SPECTRAL SIGNATURES THAT MAY BE USED TO BETTER SEARCH FOR THE ANGRITE PARENT BODY (APB).TASK 1: CURRENTLY VERY LITTLE IS KNOWN ABOUT THE VOLCANIC TO NEAR SURFACE (SHALLOW LEVEL) HISTORY OF EARLY BASALTIC MAGMATISM. THE D'ORBIGNY ANGRITE PROVIDES AN OPPORTUNITY TO EXAMINE THE SHALLOW LEVEL HISTORY OF ANGRITES BECAUSE IT CONTAINS VESICLES CAVITIES AND MESOSTASIS THAT LIKELY FORMED LATE IN THE CRYSTALLIZATION SEQUENCE. WE WILL INVESTIGATE THE PHYSICAL PROCESSES AND INTENSIVE PARAMETERS OF THE D'ORBIGNY METEORITE AND VERIFY VOLATILE CONTENTS OF THE GLASSES (E.G. C-SPECIES) AND MESOSTASIS PHASES (E.G. CL F AND S). THE PROPOSED WORK WILL HELP US MODEL THE TRANSPORT OF ANGRITIC MAGMAS TO A PLANETARY SURFACE AND BETTER CONSTRAIN EARLY SOLAR SYSTEM BUDGETS FOR MAGMATIC VOLATILES (LIKE C S CL AND F) DURING THE INITIAL STAGES OF PLANETARY DIFFERENTIATION AND MAGMATISM.TASK 2: RESOLVING THE CONDITIONS UNDER WHICH ANGRITES FORMED IS CRITICAL FOR UNDERSTANDING THEIR PETROGENESIS. MAJOR QUESTIONS EXIST ABOUT THE OXYGEN FUGACITY (FO2) OF THE ANGRITES WITH VALUES SUGGESTED FROM THE IRON-W##STITE (IW) TO THE QUARTZ-FAYALITE-MAGNETITE (QFM) BUFFER. WE WILL EVALUATE FO2 OF THE ANGRITES BY DETERMINING THE VALENCE STATE OF FE CR AND V AND TRACE ELEMENT CONTENTS IN CLINOPYROXENE RH##NITE AND GLASS IN TEXTURAL CONTEXT IN THE D'ORBIGNY METEORITE. WE WILL CONDUCT EXPERIMENTS AT CONTROLLED FO2 (IW TO QFM) TO CALIBRATE FO2 SENSORS IN THIS BULK COMPOSITION TO APPLY TO ANGRITE PETROGENESIS. WE SEEK TO ILLUMINATE BASIC COSMOCHEMICAL QUESTIONS SUCH AS HOW ELEMENTS THAT ARE ESSENTIAL FOR LIFE (E.G. C S P MN V AND FE) ARE DISTRIBUTED DURING EARLY MAGMATIC PROCESSES.TASK 3: THE PARENT BODY FOR THE ANGRITES IS UNKNOWN. REMNANT MAGNETISM SUGGESTS THAT THE ANGRITES MAY BE DERIVED FROM A BODY WITH A CORE; SOME RESEARCHERS PROPOSE THAT THEY ARE FROM MERCURY; AND NEAR-INFRARED (NEAR-IR) SPECTRA SUGGEST THAT THEY MAY BE DERIVED FROM SOME ASTEROIDS. TO PLACE FURTHER CONSTRAINTS ON THE APB WE WILL PRODUCE MAPS OF THERMAL INFRARED SPECTRA (TIR) CHEMISTRY MODAL MINERALOGY AND CRYSTALLOGRAPHIC ORIENTATION OF ANGRITES AND EXPERIMENTAL RUN PRODUCTS. THESE MAPS WILL ALLOW US TO EVALUATE HOW TIR SPECTRA ARE INFLUENCED BY MODAL MINERALOGY MINERAL CHEMISTRY AND CRYSTALLOGRAPHIC ORIENTATION AND WE WILL COLLECT SOME OF THE FIRST TIR SPECTRA OF TI-RICH FASSAITE KIRSCHSTEINITE AND ANGRITIC GLASS.THE PROPOSED STUDIES WILL CONTRIBUTE TO THE NASA GOAL OF "ADVANCING SCIENTIFIC KNOWLEDGE OF THE ORIGIN AND HISTORY OF THE SOLAR SYSTEM..." AND WILL DIRECTLY SUPPORT NASA'S ONGOING AND FUTURE MISSIONS (E.G. DAWN). ALL TASKS PROPOSED ARE HIGHLY RELEVANT TO THE COSMOCHEMISTRY PROGRAM'S GOAL TO "INCREASE THE UNDERSTANDING OF THE CHEMICAL ORIGIN OF THE SOLAR SYSTEM AND THE PROCESSES BY WHICH ITS PLANETS AND SMALL BODIES HAVE EVOLVED TO THEIR PRESENT STATES".