Are Stannern-group eucrites products of partial melt contamination?: constraining the petrogenesis of the H.E.D. parent body through experimental petrology

Abstract

Partial melting experiments were conducted on the eucrite NWA 8562 to assess the validity of partial melt assimilation models for Stannern-group eucrite petrogenesis. NWA 8562 petrography and major/minor element geochemistry were analyzed to assure that the meteorite met experimental parameters. Four sets of experiments were run at 1050, 1100, 1150, and 1200?C. Experimental compositions were analyzed and factored into calculations that model the mixing of melt fractions into Main-group eucritic magmas. We have shown that while partial melt mixing models for Stannern-group eucites can satisfy trace element constraints at 5% partial melting and 10-15%-contaminant mixtures, the model fails to account for extreme Fe-enrichment in melts, which yield compositions that are outside the range of eucrites. Previously modeled pyroxene compositions seem to be erroneous and require correction. Further research into accessory phase melt-contribution is required, and should be incorporated into the model.