MIL 03443, a dunite from asteroid 4 Vesta: Evidence for its classification and cumulate origin |
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| Authors: | Andrew W BECK David W MITTLEFEHLDT Harry Y McSWEEN Jr Douglas RUMBLE III Cin‐Ty A LEE Robert J BODNAR |
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| Institution: | 1. Department of Earth and Planetary Sciences and Planetary Geoscience Institute, University of Tennessee, Knoxville, Tennessee 37996–1410, USA;2. Astromaterials Research Office, NASA Johnson Space Center, Houston, Texas 77058, USA;3. Geophysical Laboratory, Carnegie Institution of Washington, Washington, District of Columbia 20015, USA;4. Department of Earth Science, Rice University, Houston, Texas 77005, USA;5. Department of Geosciences, Virginia Tech, Blacksburg, Virginia 24061, USA |
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| Abstract: | Abstract– The absence of dunite (>90 vol% olivine) in the howardite, eucrite, and diogenite (HED) meteorite suite, when viewed with respect to spectroscopic and petrologic evidence for olivine on Vesta, is problematic. Herein, we present petrologic, geochemical, and isotopic evidence confirming that Miller Range (MIL) 03443, containing 91 vol% olivine, should be classified with the HED clan rather than with mesosiderites. Similarities in olivine and pyroxene FeO/MnO ratios, mineral compositions, and unusual mineral inclusions between MIL 03443 and the diogenites support their formation on a common parent body. This hypothesis is bolstered by oxygen isotopic and bulk geochemical data. Beyond evidence for its reclassification, we present observations and interpretations that MIL 03443 is probably a crustal cumulate rock like the diogenites, rather than a sample of the Vestan mantle. |
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