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Olivine-dominated Asteroids: Mineralogy and Origin

Status Report From: arXiv.org e-Print archive
Posted: Monday, October 7, 2013

Olivine-dominated asteroids are a rare type of objects formed either in nebular processes or through magmatic differentiation. The analysis of meteorite samples suggest that at least 100 parent bodies in the main belt experienced partial or complete melting and differentiation before being disrupted.

However, only a few olivine-dominated asteroids, representative of the mantle of disrupted differentiated bodies, are known to exist. Due to the paucity of these objects in the main belt their origin and evolution have been a matter of great debate over the years. In this work we present a detailed mineralogical analysis of twelve olivine-dominated asteroids. Within our sample we distinguish two classes, one that we call pure-olivine asteroids and another referred to as olivine-rich asteroids. For the pure-olivine asteroids the olivine chemistry was found to range from ~ Fo49 to Fo70, consistent with the values measured for brachinites and R chondrites.

In the case of the olivine-rich asteroids we determined their olivine and low-Ca pyroxene abundance using a new set of spectral calibrations derived from the analysis of R chondrites spectra. We found that the olivine abundance for these asteroids varies from 0.68 to 0.93, while the fraction of low-Ca pyroxene to total pyroxene ranges from 0.6 to 0.9. A search for dynamical connections between the olivine-dominated asteroids and asteroid families found no genetic link (of the type core-mantel-crust) between these objects.

Juan A. Sanchez, Vishnu Reddy, Michael S. Kelley, Edward A. Cloutis, William F. Bottke, David Nesvorn, Michael P. Lucas, Paul S. Hardersen, Michael J. Gaffey, Paul A. Abell, Lucille Le Corre (Submitted on 3 Oct 2013)

Comments: 28 pages, 11 figures, 5 tables, accepted for publication in Icarus

Subjects: Earth and Planetary Astrophysics (astro-ph.EP)

Cite as: arXiv:1310.1080 [astro-ph.EP]

(or arXiv:1310.1080v1 [astro-ph.EP] for this version) Submission history From: Juan Sanchez [v1] Thu, 3 Oct 2013 20:00:01 GMT (1923kb) 

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