Tracing Oxygen Fugacity in Asteroids and Meteorites Through Olivine CompositionOlivine absorptions are known to dominate telescopic spectra of several asteroids. Among the meteorite collection, three groups (excluding Martian meteorites), the pallasites, brachinites, and R group chondrites are plausible analogs to olivine-rich asteroids in that they are dominated by olivine. These meteorite groups have distinct petrologic origins. The primitive achondrite brachinites (which include both depleted and undeleted subgroups) are products of relatively minor differentiation and evolved in oxidizing environments. R chondrites are also thought to have formed in high oxygen states, but are closely related to ordinary chondrites (yet with their own distinct compositions and oxygen isotopic signatures). In contrast, pallasites, widely thought to be mantle components from much more evolved bodies, formed in more reducing environments. Petrologic indicators that are identifiable in spectral data must be used in order to infer the petrologic history of asteroids from surveys of their actual population. As discussed below, olivine composition (e.g. Fa#) can provide key constraints in exploring the origin and significance of olivine dominated asteroids.
Sunshine, J. M. (Science Applications International Corp. Chantilly, VA, United States)
Bus, S. J. (Hawaii Univ. Honolulu, HI, United States)
Burbine, T. H. (Mount Holyoke Coll. South Hadley, MA, United States)
McCoy, T. J. (National Museum of Natural History Washington, DC, United States)
September 7, 2013
January 1, 2005
Publication: Lunar and Planetary Science XXXVI, Part 18