Mineralogy, Morphology, and Emplacement History of the Maaz Formation on the Jezero Crater Floor From Orbital and Rover Observations

Abstract

The first samples collected by the Perseverance rover on the Mars 2020 mission were from the Maaz formation, a lava plain that covers most of the floor of Jezero crater. Laboratory analysis of these samples back on Earth would provide important constraints on the petrologic history, aqueous processes, and timing of key events in Jezero crater. However, interpreting these samples requires a detailed understanding of the emplacement and modification history of the Maaz formation. Here we synthesize rover and orbital remote sensing data to link outcrop‐scale interpretations to the broader history of the crater, including Mastcam‐Z mosaics and multispectral images, SuperCam chemistry and reflectance point spectra, RIMFAX ground penetrating radar, and orbital hyperspectral reflectance and high‐resolution images. We show that the Maaz formation is composed of a series of distinct members corresponding to basaltic to basaltic‐andesite lava flows. The members exhibit variable spectral signatures dominated by high‐Ca pyroxene, Fe‐bearing feldspar, and hematite, which can be tied directly to igneous grains and altered matrix in abrasion patches. Spectral variations correlate with morphological variations, from recessive layers that produce a regolith lag in lower Maaz, to weathered polygonally fractured paleosurfaces and crater‐retaining massive blocky hummocks in upper Maaz. The Maaz members were likely separated by one or more extended periods of time, and were subjected to variable erosion, burial, exhumation, weathering, and tectonic modification. The two unique samples from the Maaz formation are representative of this diversity, and together will provide an important geochronological framework for the history of Jezero crater.

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

“…However, this accuracy issue cannot solely explain these Fe‐rich pyroxene compositions. High‐Fe content in pyroxene is consistent with the positions of pyroxene absorptions bands in both Mastcam‐Z in situ and CRISM orbital spectral data of the Máaz fm (Horgan et al., 2022).…”

“…Note that Roubion is likely transitional as it appears to be stratigraphically in between the upper and lower mbs according to Horgan et al. (2023). However, we grouped this member into the lower mb, as its composition is closest to the lower mb (see Section 3.2).…”

“… Major element compositions of textural groups defined by Horgan et al. (2023): (a) Na 2 O + K 2 O versus SiO 2 , (b) Al 2 O 3 , (c) CaO, (d) FeO versus MgO, with Martian meteorite compositions, and Gale and Gusev crater composition envelopes (see Text S1 in Supporting Information for references). Error bars represent 1 standard deviation average.…”

“…Four rock samples have been collected in the Máaz fm, including Montdenier (Sol 194) and Montagnac (Sol 196) from the Rochette rock and Hahonih (Sol 371) and Atsah (Sols 374/377) samples from the Sid rock (Figure 1). Montdenier and Montagnac represent the lower Máaz mb and Hahonih and Atsah representing the upper Máaz mb (Horgan et al., 2023; see Table for the compositions of rocks where cores were collected). The return to Earth of these samples is crucial to constrain their formation and more broadly the igneous evolution of Mars (see Simon et al., 2022; Simon et al., 2023, for description of Máaz samples and sample analyses).…”

Reflectance of Jezero Crater Floor: 2. Mineralogical Interpretation

“…Though the 1 μm band center is outside of SuperCam' spectral ranges, these bands are large enough that the high‐wavelength wing produces a strong red slope at the shortest NIR wavelengths probed by SuperCam, and the low‐wavelength wing can be observed partially by the longest SuperCam VIS wavelengths. Mastcam‐Z multispectral observations (0.44–1.02 μm) provide additional information in this region (e.g., Johnson et al., 2022; Horgan et al., 2023; Rice et al., 2023).…”