Olivine–gabbroic shergottites: A petrogenetic link between poikilitic and gabbroic shergottites

Abstract

Shergottites span a textural, mineralogical, and geochemical range, and finding links between the various petrologic and geochemical groups is of great interest as it provides insight into the conditions of the Martian interior. Here, we compare the texture, mineralogy, mineral chemistry, and geochemistry of REE-enriched intrusive shergottite groups, including poikilitic shergottites, olivine–gabbroic shergottites, and gabbroic shergottites. Due to the similarities of olivine–gabbroic samples to poikilitic and gabbroic shergottites, we suggest that the former may represent an intermediary petrologic type. We suggest a shared magmatic history for these sample groups via a shared stratified magma chamber. Thermodynamic modeling of the proposed shared magmatic history using Magma Chamber Simulator (MCS) and MELTS was able to reproduce the mineralogies and general crystallization histories of samples using a parental melt of bulk silicate mars (BSM) composition and the compositions of olivine–phyric shergottites LAR 06319 and NWA 6234.