The geology & surface mineralogy of Mars; using Martian meteorites as a ground-truth for spacecraft data

Abstract

The surface of Mars has been characterised by interpreting data from orbiting satellites and severalplanetary landers and rovers for many decades; however, there are now ~70 meteorites in collections that are believed to have originated on the surface of Mars. These meteorites provide the only in situ opportunity to study true Martian material and could serve as a ground-truth for spacecraft data. This research investigates the hypothesis that meteorite-derived, extra-terrestrial mineral spectra provide a better match to bulk rock spectra that are being measured of the surface of Mars. The key mineralogical, textural and spectroscopic features of the shergottite meteorites have been described using a multidisciplinary approach. A suite of shergottites, the most numerous sub-group of Martian meteorites, have been analysed in order to understand the mineralogical properties of this diverse group and to constrain their relative magmatic histories. The research was conducted using an array of analytical techniques and, where possible, instruments that are used for in situ and remote observations of planetary bodies such as Mars. The two main techniques used in this study, electron backscatter diffraction (EBSD) and micro-Fourier Transform Infrared (FTIR) spectroscopy, have shown their suitability for this work owing to their precision within a mineralogical context and non-destructive nature.

This PhD research has shown that EBSD in particular is an excellent, yet underused, analytical technique for use in mineralogical investigations of meteorites and has led to further characterization of their respective magmatic histories previously overlooked. This research has also characterized a suite of Martian-specific mineral spectra within the mid-IR range that have been underrepresented within spectral libraries previously, including the elusive low-Ca clinopyroxene pigeonite. The implications of this study are far-reaching; the collective techniques used here can be applied to other planetary bodies throughout the solar system.