A ferroan region of the lunar highlands as recorded in meteorites MAC88104 and MAC88105

摘要: MacAlpine Hills 88104 and 88105 (MAC88104/5) are paired meteorites of noritic anorthosite composition from the lunar highlands. MAC88105 is a breccia composed mainly melt-breccia clasts in fine-grained, fragmental, partly glassy matrix. The most abundant melt lithologies feldspathic similar to bulk meteorite. Other include rocks, mafic breccias, rare relatively enriched incompatible trace elements. Subordinate lithic granulitic breccias ferroan (relatively low Mg[Mg + Fe]) igneous lithologies, including troctolitic anorthosite, anorthositic norite, gabbronorite, anorthosite. Igneous having mineral compositions more magnesian than Fo55 En60 were not observed. Rare fragments glass spheres shards as well indicate that meteorite was derived an immature regolith. characterized by molar Mg(Mg Fe) ratio 0.62, at extreme end range for Its concentrations elements (29% Al2O3), suggest it, like other meteorites, formed site far removed areas sampled Apollo missions. Similarities among different (melt-breccia clasts, fragments) distribution components crustal section dominated material with affinity suite plutonic rocks. have roughly peritectic compositions, many “low-K Fra Mauro” collection but much ferroan, represent source distinct anorthosite. Moderate Ce anomalies, both positive negative, occur some separated lesser extent small chips matrix, powder prepared 20 g These anomalies almost certainly terrestrial weathering effects. One clast rich siderophile result large amount Fe-Ni metal. AuIr (0.64, CI-normalized) distinctly metal-rich impact melts 16 (~3, CI-normalized). The compositional observed nonmare ALHA81005, Y791197, Y82192/3, Y86032, MAC88104/5 equivalent representative samples < 1 mm fines 16. Thus, data provide little constraint on number impacts required eject these Moon.