Pairing relationships of howardites, eucrites and diogenites (HED) from the Miller Range ice fields, Antarctica

We reevaluated pairing relationships among 56 Antarctic howardites, eucrites, and diogenites (HED) from the Miller Range ice fields (MIL) based on new measurements of cosmogenic radionuclides and bulk composition of 28 HED samples and one HED-related dunite. These measurements were combined with petrographic examinations and find locations of the majority of the HED samples at MIL. During these studies, we reclassified 1 howardite, MIL 07665, as a brecciated diogenite and eight howardites as brecciated eucrites. We conclude that 18 of the 23 diogenites belong to a single large pairing group of brecciated diogenites. This pairing group includes at least seven samples with bulk compositions that indicate they contain 10%–25% of eucritic material, so technically the meteorites of this pairing group cross the boundary between diogenites and howardites. We also identified several smaller pairing groups (of 2–5 members each) among the eucrites and two paired samples among the howardites. The pairing relationships among the Miller Range eucrites are not fully resolved yet, as the collection contains many small specimens (<10 g) that were not included in this study. Altogether, we conclude that the 56 HED meteorites at Miller Range represent between 19 and 26 individual falls.