Similarities between the shergottites and terrestrial ferropicrites

Element abundance ratios have been used to both distinguish terrestrial and martian basalts and make estimates on the bulk planetary chemistry. However, these estimates are based upon ratios that are assumed to have been unaffected by igneous processes. Since the extent to which this is valid is unknown, comparisons of terrestrial and martian rocks are best conducted on rocks with similar mineralogy and petrology, and therefore a good likelihood of similar crystallization histories. When the geochemistry of terrestrial ferropicrites is compared with the olivine–phyric and basaltic shergottites, previously observed differences in chemistry are no longer definitive (i.e. Mg/Si, Al/Si, Ca/Si, Fe/Si, FeO/MnO, Al/Ti, Na/Ti, Na/Al, K/La, K/Rb, K/Th, K/U, Th/U ratios). Since ferropicrites are geochemical terrestrial analogs for the shergottites, their formation history can provide useful information about the formation of the shergottites. This suggests that both ferropicrites and shergottites formed from a heavily processed mantle source region.