|Northwest Africa 7034|
|Basic information||Name: Northwest Africa 7034|
This is an OFFICIAL meteorite name.
Abbreviation: NWA 7034
Observed fall: No
Year found: 2011
Mass: 320 g
This is 1 of 2 approved meteorites classified as Martian (basaltic breccia). [show all]
Search for other: Martian meteorites
Approved 24 Jan 2012|
Revised 4 Jan 2013: Updated classification and info
Writeup from MB 100:
Northwest Africa 7034 (NWA 7034)
Classification: Ungrouped achondrite
History: Purchased by Jay Piatek from AHabibi in Morocco, 2011.
Physical characteristics: Single stone, shiny, black surface, saw cut reveals porphyritic breccia with numerous dark and light colored phenocrysts and clasts of variable size and texture, set in a dark groundmass, many reflective opaques visible.
Petrography: (C. Agee, UNM) Microprobe examination of two polished epoxy mounts show a porphyritic, brecciated texture with plagioclase and pyroxene phenocrysts to 5 mm, ubiquitous chlorapatite, ilmenite, magnetite, and trace K-feldspar. Fine-grained groundmass composed of plagioclase, pyroxene, oxides, and trace Fe-sulfides. Poikilitic pyroxene-plagioclase clasts and quench melt clasts present. No Fe-Ni metal observed.
Geochemistry: (C. Agee , N. Wilson, F. McCubbin, UNM) Plagioclase Ab52±6An45±7Or3±1, n=10, low-Ca pyroxene Fs31.6±6.7Wo3.1±0.8, Fe/Mn=37±3, n=23, pigeonite Fs35.5±3.5Wo8.0±3.3, Fe/Mn=34±1, n=8, augite Fs24.3±4.5Wo38.7±4.6, Fe/Mn=32±6, n=12, apatite with Cl=4.85±0.34 F=0.70±0.13 F+Cl=-O 1.38±0.06 (wt%) n=16, ilmenite with up to 5.3 wt% MgO, magnetite with up to 22.5 wt% Cr2O3, K-feldspar Or77Ab21An3. Oxygen isotopes (Z. Sharp, UNM): acid-washed material analyzed in replicate by laser fluorination gave, respectively δ18O=6.00, 5.79, 6.51, 6.32; δ17O=3.76, 3.52, 4.09, 3.89; Δ17O= +0.59, +0.46, +0.65, +0.55 (all per mil).
Classification: Achondrite ungrouped (basaltic breccia). Plagioclase and pyroxene compositions similar to basaltic shergottites, however the oxygen isotopic values are higher than the SNC fractionation array.
Specimens: 30 g including a probe mount on deposit at UNM, Jay Piatek holds the main mass.
Writeup from MB 101:
Northwest Africa 7034 (NWA 7034), updated information, based on Agee et al. (2013)
Revised classification: Martian, Basaltic Breccia
Updated petrography (C. Agee, UNM): Porphyritic basaltic monomict breccia, with a few euhedral phenocrysts up to several millimeters and many phenocryst fragments of dominant andesine, low-Ca pyroxene, pigeonite, and augite set in a very fine-grained, clastic to plumose, groundmass with abundant magnetite and maghemite; accessory sanidine, anorthoclase, Cl-rich apatite, ilmenite, rutile, chromite, pyrite, and goethite, identified by electron microprobe analyses on eight different sections at UNM. X-ray diffraction analyses conducted at UNM on a powdered sample and on a polished surface show that plagioclase feldspar is the most abundant phase (38.0±1.2%), followed by low-Ca pyroxene (25.4±8.1%), clinopyroxenes (18.2±4.0%), iron-oxides (9.7±1.3%), alkali feldspars (4.9±1.3%), and apatite (3.7±2.6%). The x-ray data also indicate a minor amount of iron-sulfide and chromite. The data are also consistent with magnetite and maghemite making up ~70% and ~30%, respectively, of the iron oxide detected.
Additional geochemical data. Rb-Sr age (V. Polyak, Y. Asmerom, N. Wilson, UNM): 2.089±0.081 Ga (2-σ). REE: La=58 × CI, (La/Yb)=2.3. Hydrogen isotopes (Z. Sharp, K. Ziegler, UNM): six whole-rock combustion measurements yielded a bulk water content of 6190±620 ppm. The mean δD value for the bulk combustion analyses was +46.3±8.6‰. The maximum δD values in two separate stepwise heating experiments were +319‰ and +327‰, reached at 804°C and 1014°C respectively. Oxygen isotopes (Z. Sharp, K. Ziegler, UNM; M. Nunn, UCSD): 21 analyses of bulk NWA 7034 were carried out. The mean value obtained at UNM was Δ17O=0.58±0.05‰ n=13 for acid washed samples and Δ17O=0.60±0.02‰ n=6 for non-acid-washed samples; at UCSD the mean value was Δ17O=0.50±0.03‰ n=2 for vacuum pre-heated samples that were dewatered and decarbonated. The combined data give Δ17O=0.58±0.05‰ n=21.
UNM: Institute of Meteoritics, Department of Earth and Planetary Sciences, University of New Mexico, Albuquerque, NM 87131, USA (institutional address)
AHabibi: Palms Hotel Club, Erfoud 52200, Morocco (private address; updated 3 Jan 2010)
UCSD: Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, CA 92093, United States (institutional address; updated 4 Jan 2013)
|References:||Published in Meteoritical Bulletin, no. 100, MAPS 46, in preparation (2013)|
Published in Meteoritical Bulletin, no. 101, MAPS 47, in preparation (2013)
This is 1 of 831 approved meteorites from Morocco (plus 8 unapproved names)
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