A Mars 2020 Perseverance SuperCam Perspective on the Igneous Nature of the Máaz Formation at Jezero Crater and Link With Séítah, Mars

Abstract

The Máaz formation consists of the first lithologies in Jezero crater analyzed by the Mars 2020 Perseverance rover. This formation, investigated from Sols (Martian days) 1 to 201 and from Sols 343 to 382, overlies the Séítah formation (previously described as an olivine‐rich cumulate) and was initially suggested to represent an igneous crater floor unit based on orbital analyses. Using SuperCam data, we conducted a detailed textural, chemical, and mineralogical analyses of the Máaz formation and the Content member of the Séítah formation. We conclude that the Máaz formation and the Content member are igneous and consist of different lava flows and/or possibly pyroclastic flows with complex textures, including vesicular and non‐vesicular rocks with different grain sizes. The Máaz formation rocks exhibit some of the lowest Mg# (=molar 100 × MgO/MgO + FeO) of all Martian igneous rocks analyzed so far (including meteorites and surface rocks) and show similar basaltic to basaltic‐andesitic compositions. Their mineralogy is dominated by Fe‐rich augite to possibly ferrosilite and plagioclase, and minor phases such as Fe‐Ti oxides and Si‐rich phases. They show a broad diversity of both compositions and textures when compared to Martian meteorites and other surface rocks. The different Máaz and Content lava or pyroclastic flows all originate from the same parental magma and/or the same magmatic system, but are not petrogenetically linked to the Séítah formation. The study of returned Máaz samples in Earth‐based laboratories will help constrain the formation of these rocks, calibrate Martian crater counting, and overall, improve our understanding of magmatism on Mars.

Plain Language Summary

The Mars 2020 Perseverance rover landed on Mars in the Jezero crater on 18 February 2021. The main goals of this mission are to constrain the geology of the Jezero crater and its delta, to search for biosignatures (evidence of ancient life), to sample rocks to return to Earth, and to prepare for human exploration. Here we study the rock formation observed at the landing site, named the Máaz formation. We conclude that this rock formation is igneous (=formed from cooling and crystallization of lava or magma) consisting of iron‐rich basaltic lava flows, formed through effusive (i.e., outpouring of lava without explosions) volcanism. When compared to other Martian magmatic rocks, these rocks show a large variety of textures (shape and size of minerals) and compositions, making them different from the Martian magmatic rocks studied so far. The various lava flows of the Máaz rocks are likely all related, but not related to the underlying Séítah rock formation. Perseverance has collected core samples from the Máaz and Séítah rocks that could be among the Martian rocks to be returned to Earth in the 2030s. Their study in Earth‐based laboratories will allow us to better understand the evolution of Martian magmatism.

Key Points

• The Máaz formation in Jezero crater consists of basaltic to basaltic‐andesite lava flows likely originating from the same parental magma

• The Máaz formation shows various igneous textures and has a different magmatic history than the other known Martian igneous rocks

• The study of samples from the Máaz formation on Earth will help constrain the Martian cratering chronology and Martian igneous evolution