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Igneous petrology of the new ureilites Nova 001 and Nullarbor 010The Nova 001 (= Nuevo Mercurio (b)) and Nullarbor 010 meteorites are ureilites, both of which contain euhedral graphite crystals. The bulk of the meteorites are olivine (Fo79) and pyroxenes (Wo9En73Fs18, Wo3En77Fs20), with a few percent graphite and minor amounts of troilite, Ni-Fe metal, and possibly diamond. The rims of olivine grains are reduced (to Fo91) and contain abundant blebs of Fe metal. Silicate mineral grains are equant, anhedral, up to 2 mm across, and lack obvious preferred orientations. Euhedral graphite crystals (to 1 mm x 0.3 mm) are present at silicate grain boundaries, along boundaries and protruding into the silicates, and entirely within silicate mineral grains. Graphite euhedra are also present as radiating clusters and groups of parallel plates grains embedded in olivine; no other ureilite has comparable graphite textures. Minute lumps within graphite grains are possible diamond, inferred to be a result of shock. Other shock effects are limited to undulatory extinction and fracturing. Both ureilites have been weathered significantly. Considering their similar mineralogies, identical mineral compositions, and identical unusual textures, Nova 001 and Nullarbor 010 are probably paired. Based on olivine compositions, Nova 001 and Nullarbor 010 are in Group 1 (FeO-rich) of Berkley et al. (1980). Silicate mineral compositions are consistent with those of others known ureilites. The presence of euhedral graphite crystals within the silicate minerals is consistent with an igneous origin, and suggests that large proportions of silicate magma were present locally and crystallized in situ.
Document ID
19950035636
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
Authors
Triman, Allan H.
(NASA Johnson Space Center Houston, TX, United States)
Berkley, John L.
(State Univ. of New York, Fredonia, NY, United States)
Date Acquired
August 16, 2013
Publication Date
November 1, 1994
Publication Information
Publication: Meteoritics
Volume: 29
Issue: 6
ISSN: 0026-1114
Subject Category
Lunar And Planetary Exploration
Accession Number
95A67235
Funding Number(s)
CONTRACT_GRANT: NAG9-82
Distribution Limits
Public
Copyright
Other

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