Research Training ProgramSmithsonian
Institution
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| Ellen B. Rosenshein Binghamton University Binghamton, New York Tim McCoy, Ph.D. "Working at the Smithsonian has helped to solidify my desire to work in planetary geology." |
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Research Training ProgramSmithsonian
Institution
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|
| Ellen B. Rosenshein Binghamton University Binghamton, New York Tim McCoy, Ph.D. "Working at the Smithsonian has helped to solidify my desire to work in planetary geology." |
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A Mineralogical Study of Aubritic Meteorites: Evidence for Partial Melting
ABSTRACT
Aubrites, which are asteroidal meteorites, are breccias composed of igneous clasts. They are coarse-grained, and can contain up to 10 cm enstatite clasts. Aubrites are interesting because they formed in an environment with essentially no free oxygen, and therefore, contain a diverse suite of minerals that are unknown on Earth. These include troilite, alabandite, djerfisherite, oldhamite, schreibersite and daubreelite. Aubrites are the products of melting and differentiation on the asteroidal parent body. The precursor to aubrites was enstatite chondrite-like, and was altered through partial melting and later migration of these melts. These were basaltic metal-sulfide melts, but the real question is, where did the partial melts go? Aubrites may be the residues from this early partial melting, which underwent continued melting and differentiation. These partial melts may have been locally redistributed. Eventually, they crystallized and should produce complex metal-sulfide-silicate clasts. In this study, several aubrites were searched to find clasts that represented these melts. Mineralogical, petrological and chemical examinations of these clasts was conducted using optical microscopy, cathodoluminescence, scanning electron microscopy, and the electron microprobe. Clasts were found exhibiting these complex crystallization histories. These clasts may elucidate the processes of crystallization, melt immiscibility, late-stage oxidation, and solid-melt reactions. A fuller understanding of these processes should shed new light on the formation of aubrites.
This research was supported by a NSF-REU grant - award number EAR-9732416.