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 will provide important constraints on the petrologic history, aqueous processes, and timing of key events in Jezero. However, interpreting these samples will require 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. Hosted fileessoar.10512674.1.docx available at https://authorea.com/users/531790/articles/620328mineralogy-morphology-and-emplacement-history-of-the-maaz-formation-on-the-jezerocrater-floor-from-orbital-and-rover-observations Mineralogy, morphology, and emplacement history of the Maaz formation on the Jezero crater floor from orbital and rover observations

Regolith of the Crater Floor Units, Jezero Crater, Mars: Textures, Composition, and Implications for Provenance

“…As discussed in Section 4.2.1, Figure 9 illustrates the overall similarity between the rock fragments and pebbles present in the mixed regolith and neighboring in‐place unit rocks. Mastcam‐Z spectra of Máaz formation rocks reported elsewhere (Bell et al., 2022; Farley et al., 2022; B. Horgan et al., 2022; Rice et al., 2022a) are characterized by peak reflectances at 754 nm and NIR absorptions that fall between 866 and 940 nm. The similarity in the presence and position of absorptions between the bedrock and rock fragment spectra in Máaz shows the idea that the fragments are eroded from local bedrock (Figure 9a).…”

SHERLOC Raman Mineral Class Detections of the Mars 2020 Crater Floor Campaign

“…Séítah is overlain by Máaz, previously referred to as the Crater Floor Fractured Rough (CF‐Fr) Unit, which is light‐toned and polygonally fractured. Results from the Perseverance payload during the Crater Floor Campaign indicate that both Máaz and Séítah are igneous in origin (Horgan et al., 2022). Máaz is characterized by the presence of abundant pyroxene (Schmidt et al., 2022; Udry et al., 2022), while Séitah is an olivine cumulate (Brown et al., 2022: Farley et al., 2022; Liu et al., 2022; Núñez et al., 2022; Wiens et al., 2022).…”

RIMFAX Ground Penetrating Radar Reveals Dielectric Permittivity and Rock Density of Shallow Martian Subsurface

“…Its composition is basaltic to basaltic‐andesitic. Spectral variability and morphology of Máaz‐outcrops lead to further distinction of the Máaz‐subregions, upper and lower Máaz, encompassing the eastern, respectively, southern part, with a transitional zone around the south‐eastern tip of Séítah (Horgan et al., 2022). In contrast to Máaz, Séítah is interpreted as an olivine cumulate formed by slow cooling magma (Liu et al., 2022; Wiens et al., 2022).…”

“…For other samples like olivine and plagioclase, they do not find a temperature dependence to be significant within the uncertainty and frequency range of our study. While the materials of Stillman and Olhoeft (2008) have been found in Jezero Crater rocks (e.g., Farley et al, 2022;Horgan et al, 2022;Wiens et al, 2022), the temperature-independent substances are the more abundant. Therefore, we consider temperature effects to be negligible for the purposes of this work.…”