Olivine‐Carbonate Mineralogy of the Jezero Crater Region

Abstract

A well‐preserved, ancient delta deposit, in combination with ample exposures of carbonate outcrops, makes Jezero Crater in Nili Fossae a compelling astrobiological site. We use Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) observations to characterize the surface mineralogy of the crater and surrounding watershed. Previous studies have documented the occurrence of olivine and carbonates in the Nili Fossae region. We focus on correlations between these two well‐studied lithologies in the Jezero crater watershed. We map the position and shape of the olivine 1 μm absorption band and find that carbonates are found in association with olivine which displays a 1 μm band shifted to long wavelengths. We then use Thermal Emission Imaging Spectrometer (THEMIS) coverage of Nili Fossae and perform tests to investigate whether the long wavelength shifted (redshifted) olivine signature is correlated with high thermal inertia outcrops. We find that there is no consistent correlation between thermal inertia and the unique olivine signature. We discuss a range of formation scenarios for the olivine and carbonate associations, including the possibility that these lithologies are products of serpentinization reactions on early Mars. These lithologies provide an opportunity for deepening our understanding of early Mars and, given their antiquity, may provide a framework to study the timing of valley networks and the thermal history of the Martian crust and interior from the early Noachian to today.

Crater Morphometry on the Mafic Floor Unit at Jezero Crater, Mars: Comparisons to a Known Basaltic Lava Plain at the InSight Landing Site

“…We propose that the gradational transition from rough to smooth texture represents incomplete regolith deflation or exhumation of the MFU. The erosion indicated here may also be regionally important, reflected in the well-exposed delta stratigraphy in Jezero and the impressive mineral detections (Brown et al, 2020;Goudge et al, 2012Goudge et al, , 2015Schon et al, 2012).…”

Mars 2020 Mission Overview

“…Light-toned, fractured, and olivine-carbonate-bearing deposits have been observed both within and outside Jezero crater, and draping the crater rim. Due to morphological and mineralogical similarities between these deposits, previous studies have correlated the lighttoned fractured, olivine-carbonate-bearing units within Jezero with regionally extensive, olivine-bearing rocks observed throughout the Nili Fossae and NE Syrtis regions (Goudge et al 2015;Bramble et al 2017;Brown et al 2020;Mandon et al 2020). Further analysis of this unit emerging from a Mars 2020 Landing Site Working Group addressed an alternative hypothesis that the carbonate-bearing deposits within Jezero crater could represent carbonate minerals evaporatively precipitated at the lake margin -a scenario highly conducive to biosignature preservation.…”

Mars 2020 Team Using Australian Rocks in Search for Life on Mars

“…The recent study of Brown et al (2020) reported that within the olivinecarbonate lithology, there is band saturation of the olivine 1 μm band complex. Band saturation occurs when the grain size of the scattering crystal is large enough that photons entering the grain never make it out.…”