Magnesian anorthositic granulites in lunar meteorites Allan Hills A81005 and Dhofar 309: Geochemistry and global significance

摘要: Abstract– Fragments of magnesian anorthositic granulite are found in the lunar highlands meteorites Allan Hills (ALH) A81005 and Dhofar (Dho) 309. Five analyzed clasts meteoritic have Mg′ [molar Mg/(Mg + Fe)] = 81–87; FeO ≈ 5% wt; Al2O3 ≈ 22% wt; rare earth elements abundances ≈ 0.5–2 × CI (except Eu ≈ 10 × CI); low Ni Co a non-chondritic ratio. The nearly identical chemical compositions, even though their host formed at different places on Moon. These granulites distinct from other materials unique combination mineral proportions, Mg′, REE abundances patterns, Ti/Sm ratio, Sc/Sm Their is too high for close relationship to ferroan anorthosites, or as flotation cumulates magma ocean. Compositions these cannot be modeled mixtures of, fractionates from, known rocks. However, compositions can represented granulite, anorthosite, mare basalt, KREEP. Meteoritic good candidate component inferred Apollo highland impactites: magnesian, feldspathic, REE-poor. Bulk meteorite comparable those parts farside (the Feldspathic Highlands Terrane): ∼4.5 wt% FeO; ∼28 Al2O3; Th <1 ppm. Thus, may widespread abundant highlands.