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Petrogenesis of the Northwest Africa 4734 basaltic lunar meteorite

Wang, Ying and Hsu, Weibiao and Guan, Yunbin and Li, Xianhua and Li, Qiuli and Liu, Yu and Tang, Guoqiang (2012) Petrogenesis of the Northwest Africa 4734 basaltic lunar meteorite. Geochimica et Cosmochimica Acta, 92 . pp. 329-344. ISSN 0016-7037. https://resolver.caltech.edu/CaltechAUTHORS:20120927-120537944

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Abstract

We report the petrography, mineralogy, trace element abundance geochemistry, and Pb–Pb geochronology of the lunar meteorite Northwest Africa (NWA) 4734 and make a comparison with the LaPaz Icefield (LAP) 02205/02224 low-Ti lunar basaltic meteorites. NWA 4734 is an unbrecciated low-Ti mare basalt composed mainly of subophitic-textured pyroxene (60 vol%) and plagioclase (30%). Pyroxene, plagioclase, and olivine exhibit large compositional variations and intra-grain chemical zoning. Pyroxene and plagioclase in NWA 4734 have rare earth element (REE) concentrations and patterns similar to those of the LAPs. The crystallization age of NWA 4734, determined in situ in baddeleyite, is 3073 ± 15 Ma (2σ), nearly identical to that of the LAPs (3039 ± 12 Ma). NWA 4734 and the LAPs have similar textures, modal abundances, mineral chemistry, and crystallization ages, and are most likely source-crater paired on the Moon. One baddeleyite grain in LAP 02224 displays distinctively older and spatially variable ages, from 3349 ± 62 to 3611 ± 62 Ma (2σ), similar to another baddeleyite grain (3109 ± 29 to 3547 ± 21 Ma) reported by Zhang et al. (2010) for the same meteorite. Raman spectra, cathodoluminescence, and stoichiometric studies of the baddeleyite suggest that the two older grains were not endogenic but were trapped by the parental magma. Equilibrium partition calculation shows that the parental melt from which the NWA 4734 plagioclase crystallized has much lower REE contents than its whole rock, indicating an open system during magma evolution. NWA 4734 could have originated from a parental melt with REE concentrations similar to that of the Apollo 12 olivine basalt. The magma likely assimilated a small amount (∼4 wt%) of KREEP-rich material during its ascent through the lunar crust.


Item Type:Article
Related URLs:
URLURL TypeDescription
http://dx.doi.org/10.1016/j.gca.2012.06.024DOIArticle
http://www.sciencedirect.com/science/article/pii/S0016703712003778PublisherArticle
ORCID:
AuthorORCID
Guan, Yunbin0000-0002-7636-3735
Additional Information:© 2012 Elsevier Ltd. Received 17 November 2011; accepted in revised form 18 June 2012; available online 4 July 2012. Associate editor: Christian Koeberl. We thank the Meteorite Working Group for the samples of LAP 02224,36, 02224,28, and 02205,7. We are grateful to Drs. James M.D. Day, Bradley L. Jolliff, Kentaro Terada, Randy L. Korotev, Christian Koeberl (A.E.), and an anonymous reviewer, whose critical and constructive comments and suggestions have improved the quality of this work. Prof. Pei Ni and Dr. Junying Ding are appreciated for assistance with Raman spectrum analysis. This work was supported by the National Natural Science Foundation of China (Grant No. 41003026, 41173076 and 10921063), Natural Science Foundation of Jiangsu Province (BK2011891), international cooperation project of the Polar Research Institute of China (IC201107), and the Minor Planet Foundation of China.
Funders:
Funding AgencyGrant Number
National Natural Science Foundation of China41003026
National Natural Science Foundation of China41173076
National Natural Science Foundation of China10921063
Natural Science Foundation of Jiangsu ProvinceBK2011891
Polar Research Institute of ChinaIC201107
Minor Planet Foundation of ChinaUNSPECIFIED
Record Number:CaltechAUTHORS:20120927-120537944
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20120927-120537944
Official Citation:Ying Wang, Weibiao Hsu, Yunbin Guan, Xianhua Li, Qiuli Li, Yu Liu, Guoqiang Tang, Petrogenesis of the Northwest Africa 4734 basaltic lunar meteorite, Geochimica et Cosmochimica Acta, Volume 92, 1 September 2012, Pages 329-344, ISSN 0016-7037, 10.1016/j.gca.2012.06.024. (http://www.sciencedirect.com/science/article/pii/S0016703712003778)
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:34508
Collection:CaltechAUTHORS
Deposited By: Ruth Sustaita
Deposited On:28 Sep 2012 17:46
Last Modified:27 Nov 2019 17:02

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