Geochemistry and petrography of the MacAlpine Hills lunar meteorites

摘要: Abstract MacAlpine Hills 88104 and 88105 are anorthositic lunar meteorites recovered from the same area in Antarctica which demonstrated to be paired samples of fall. Petrographic studies matrix clasts show that MAC88104/5 is a polymict breccia dominated by impact melt clasts. It contains small amount highland glass very few regolith spherules. better classified as fragmental than breccia. The bulk composition ferroan ( mg ' = 63) highly aluminous Al 2 O 3 28%). REE other incompatible element concentrations low. Compositions anorthositic, granulitic, similar to, but distinct from, composition. meteorites, each distinct. especially Y82192/3/86032, North Ray Crater feldspathic breccias compositon petrography. These may have been ancient, deeply buried megaregolith. Comparisons chemical-petrographic features exposure histories suggest twelve were derived two nine, probably four seven, impacts onto surface. Discrepancies between proportions results Apollo missions due unrepresentative sampling. Lunar provide valuable new information on nature crust.