Geochemistry and mineralogy of a feldspathic lunar meteorite (regolith breccia), Northwest Africa 2200

Hiroshi Nagaoka, Yuzuru Karouji, Tomoko Arai, Mitsuru Ebihara, Nobuyuki Hasebe

Research output: Contribution to journalArticle

5 Citations (Scopus)

Abstract

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).

Original languageEnglish
Pages (from-to)241-259
Number of pages19
JournalPolar Science
Volume7
Issue number3-4
DOIs
Publication statusPublished - 2013 Sep
Externally publishedYes

Keywords

  • Ferroan anorthosite
  • Geochemistry
  • Lunar meteorite
  • Mineralogy

ASJC Scopus subject areas

  • Ecology, Evolution, Behavior and Systematics
  • Aquatic Science
  • Ecology
  • Earth and Planetary Sciences(all)

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