TY - JOUR
T1 - Petrography and geochemistry of the chassignite Northwest Africa 2737 (NWA 2737)
AU - Beck, P.
AU - Barrat, J. A.
AU - Gillet, Ph
AU - Wadhwa, M.
AU - Franchi, I. A.
AU - Greenwood, R. C.
AU - Bohn, M.
AU - Cotten, J.
AU - van de Moortèle, B.
AU - Reynard, B.
N1 - Funding Information:
Carine and Bruno Fectay generously provided the NWA 2737 sample. We thank Christian Koeberl for the editorial handling, Ahmed El Goresy and Harry McSween Jr for constructive comments. Access to the Washington University ion microprobe was possible through the kind courtesy of E. Zinner and C. Floss. The CLYME (Consortium Lyonnais de Microscopie Electronique) is gratefully acknowledged for the use of the TEM facilities and the GEMPPM (Groupe d’Etude de Métallurgie Physique et de Physique des Matériaux) for granting access to the SEM. Raman spectroscopy measurements were made on a INSU (Institut National des Sciences de l’Univers) national instrument. This work was partly supported by NASA Grant NAG5-12077 MW. P.B. thanks Hervé Bertrand for helpful discussions. This research made benefit of the Mars Meteorite Compendium compiled by Charles Meyer.
PY - 2006/4/15
Y1 - 2006/4/15
N2 - We report on the petrology and geochemistry of the Northwest Africa 2737 (NWA 2737) meteorite that was recovered from the Morrocan Sahara in 2000. It is the second member of the chassignite subclass of the SNC (Shergotitte-Nakhlite-Chassignite) group of meteorites that are thought to have originated on Mars. It consists of black olivine- and spinel-cumulate crystals (89.7 and 4.6 wt%, respectively), with intercumulus pyroxenes (augite 3.1 wt% and pigeonite-orthopyroxene 1.0 wt%), analbite glass (1.6 wt%) and apatite (0.2 wt%). Unlike Chassigny, plagioclase has not been observed in NWA 2737. Olivine crystals are rich in Mg, and highly equilibrated (Fo = 78.7 ± 0.5 mol%). The black color of olivine grains may be related to the strong shock experienced by the meteorite as revealed by the deformation features observed on the macroscopic to the atomic scale. Chromite is zoned from core to rim from Cr83.4Uv3.6Sp13.0 to Cr72.0Uv6.9Sp21.1. Pyroxene compositional trends are similar to those described for Chassigny except that they are richer in Mg. Compositions range from En78.5Wo2.7Fs18.8 to En76.6Wo3.2Fs20.2 for the orthopyroxene, from En73.5Wo8.0Fs18.5 to En64.0Wo22.1Fs13.9for pigeonite, and from En54.6Wo32.8Fs12.6 to En46.7Wo44.1Fs9.2 for augite. Bulk rock oxygen isotope compositions confirm that NWA 2737 is a new member of the martian meteorite clan (Δ17O = 0.305 ± 0.02‰, n = 2). REE abundances measured in NWA 2737 mineral phases are similar to those in Chassigny and suggest a genetic relationship between these two rocks. However, the parent melt of NWA 2737 was less evolved and had a lower Al abundance.
AB - We report on the petrology and geochemistry of the Northwest Africa 2737 (NWA 2737) meteorite that was recovered from the Morrocan Sahara in 2000. It is the second member of the chassignite subclass of the SNC (Shergotitte-Nakhlite-Chassignite) group of meteorites that are thought to have originated on Mars. It consists of black olivine- and spinel-cumulate crystals (89.7 and 4.6 wt%, respectively), with intercumulus pyroxenes (augite 3.1 wt% and pigeonite-orthopyroxene 1.0 wt%), analbite glass (1.6 wt%) and apatite (0.2 wt%). Unlike Chassigny, plagioclase has not been observed in NWA 2737. Olivine crystals are rich in Mg, and highly equilibrated (Fo = 78.7 ± 0.5 mol%). The black color of olivine grains may be related to the strong shock experienced by the meteorite as revealed by the deformation features observed on the macroscopic to the atomic scale. Chromite is zoned from core to rim from Cr83.4Uv3.6Sp13.0 to Cr72.0Uv6.9Sp21.1. Pyroxene compositional trends are similar to those described for Chassigny except that they are richer in Mg. Compositions range from En78.5Wo2.7Fs18.8 to En76.6Wo3.2Fs20.2 for the orthopyroxene, from En73.5Wo8.0Fs18.5 to En64.0Wo22.1Fs13.9for pigeonite, and from En54.6Wo32.8Fs12.6 to En46.7Wo44.1Fs9.2 for augite. Bulk rock oxygen isotope compositions confirm that NWA 2737 is a new member of the martian meteorite clan (Δ17O = 0.305 ± 0.02‰, n = 2). REE abundances measured in NWA 2737 mineral phases are similar to those in Chassigny and suggest a genetic relationship between these two rocks. However, the parent melt of NWA 2737 was less evolved and had a lower Al abundance.
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U2 - 10.1016/j.gca.2006.01.016
DO - 10.1016/j.gca.2006.01.016
M3 - Article
AN - SCOPUS:33645884999
SN - 0016-7037
VL - 70
SP - 2127
EP - 2139
JO - Geochimica et Cosmochimica Acta
JF - Geochimica et Cosmochimica Acta
IS - 8
ER -