Geochemical study of the NWA 6148 Martian meteorite and its terrestrial weathering processes

Abstract

The NWA 6148 meteorite was found in the region of Northwest Africa and is one of the 18 Martian meteorites catalogued as nakhlites. Due to their scarcity and their Natural Heritage value, their study is essential and provides relevant information about Mars’ surface composition. However, even if their study could result crucial, there are almost no studies about this nakhlite and there is a lack of knowledge about meteorite NWA 6148. In this work, a sample of the NWA 6148 meteorite was analyzed by means of Raman spectroscopy and Scanning Electron Microscopy coupled to Energy Dispersive Spectroscopy (SEM-EDS) coupled to a Raman spectrometer (SCA analyzer). Regarding the Martian original materials, augite and olivine were observed. Their metal composition was estimated through Raman bands position, obtaining a common composition for augite and for olivine grain rims, but discovering several olivine grain cores with the greatest magnesium content among nakhlites. Regarding terrestrial weathering products, calcium was identified, which was formed due to carbonate rich water evaporation in desert areas. Besides, a cobalt compound was discovered for the very first time in a Martian meteorite, the Co3O4, which integrated in this nakhlite’s structure after its impact on Earth’s surface. Finally, several organic compounds were observed in the meteorite sample, which were related to contamination during its handling.