TY - JOUR
T1 - Geochemistry and mineralogy of a feldspathic lunar meteorite (regolith breccia), Northwest Africa 2200
AU - Nagaoka, Hiroshi
AU - Karouji, Yuzuru
AU - Arai, Tomoko
AU - Ebihara, Mitsuru
AU - Hasebe, Nobuyuki
N1 - Funding Information:
PGA and INAA studies were conducted under the inter-university cooperative research program between the Japan Atomic Energy Agency and the University of Tokyo. Mineralogical analyses were supported by the National Institute of Polar Research and the cooperative program (2011 , No. 107, H. Takeda) of the Atmosphere and Ocean Research Institute at the University of Tokyo. This work was supported in part by Research Fellowships for Young Scientists from the Japan Society for the Promotion of Science . We greatly appreciate the thorough reviews and helpful comments by Kazuo Shibuya, Takaaki Noguchi, Katherine Joy, and anonymous reviewers.
PY - 2013/9
Y1 - 2013/9
N2 - The lunar meteorite Northwest Africa (NWA) 2200 is a regolith breccia with a ferroan feldspathic bulk composition (Al2O3=30.1wt.%; Mg#=molar 100×Mg/(Mg+Fe)=59.2) and low Th content (0.42μg/g). Lithologically, NWA 2200 is a diverse mixture of lithic and glassy clasts, mineral fragments, and impact glass spherules, all embedded in a dark glassy matrix. NWA 2200 contains some feldspathic brecciated rock components (ferroan anorthositic granulitic breccia, poikiloblastic granulitic breccia, and glassy melt breccia with an intersertal texture). The bulk compositions of these brecciated components indicate they are derived from ferroan troctolitic or noritic anorthosite lithologies (bulk Al2O3=26-30wt.%; bulk FeO/MgO>1.0). The bulk composition of NWA 2200 is more ferroan and feldspathic than the Apollo feldspathic regolith samples and feldspathic lunar regolith meteorites, and is also more depleted in incompatible elements (e.g., rare earth elements) than Apollo 16 feldspathic regolith samples. We conclude that NWA 2200 originated from a location different to the Apollo landing sites, and may have been sourced from the ferroan KREEP-poor highlands, "KREEP" materials are enriched in such elements as potassium (K), rare earth elements (REE), phosphorus (P).
AB - The lunar meteorite Northwest Africa (NWA) 2200 is a regolith breccia with a ferroan feldspathic bulk composition (Al2O3=30.1wt.%; Mg#=molar 100×Mg/(Mg+Fe)=59.2) and low Th content (0.42μg/g). Lithologically, NWA 2200 is a diverse mixture of lithic and glassy clasts, mineral fragments, and impact glass spherules, all embedded in a dark glassy matrix. NWA 2200 contains some feldspathic brecciated rock components (ferroan anorthositic granulitic breccia, poikiloblastic granulitic breccia, and glassy melt breccia with an intersertal texture). The bulk compositions of these brecciated components indicate they are derived from ferroan troctolitic or noritic anorthosite lithologies (bulk Al2O3=26-30wt.%; bulk FeO/MgO>1.0). The bulk composition of NWA 2200 is more ferroan and feldspathic than the Apollo feldspathic regolith samples and feldspathic lunar regolith meteorites, and is also more depleted in incompatible elements (e.g., rare earth elements) than Apollo 16 feldspathic regolith samples. We conclude that NWA 2200 originated from a location different to the Apollo landing sites, and may have been sourced from the ferroan KREEP-poor highlands, "KREEP" materials are enriched in such elements as potassium (K), rare earth elements (REE), phosphorus (P).
KW - Ferroan anorthosite
KW - Geochemistry
KW - Lunar meteorite
KW - Mineralogy
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U2 - 10.1016/j.polar.2013.09.001
DO - 10.1016/j.polar.2013.09.001
M3 - Article
AN - SCOPUS:84897080659
SN - 1873-9652
VL - 7
SP - 241
EP - 259
JO - Polar Science
JF - Polar Science
IS - 3-4
ER -