Diverse organic-mineral associations in Jezero crater, Mars

Abstract

The presence and distribution of preserved organic matter on the surface of Mars can provide key information about the Martian carbon cycle and the potential of the planet to host life throughout its history. Several types of organic molecules have been previously detected in Martian meteorites1 and at Gale crater, Mars2–4. Evaluating the diversity and detectability of organic matter elsewhere on Mars is important for understanding the extent and diversity of Martian surface processes and the potential availability of carbon sources1,5,6. Here we report the detection of Raman and fluorescence spectra consistent with several species of aromatic organic molecules in the Máaz and Séítah formations within the Crater Floor sequences of Jezero crater, Mars. We report specific fluorescence-mineral associations consistent with many classes of organic molecules occurring in different spatial patterns within these compositionally distinct formations, potentially indicating different fates of carbon across environments. Our findings suggest there may be a diversity of aromatic molecules prevalent on the Martian surface, and these materials persist despite exposure to surface conditions. These potential organic molecules are largely found within minerals linked to aqueous processes, indicating that these processes may have had a key role in organic synthesis, transport or preservation.

Overview and Results From the Mars 2020 Perseverance Rover's First Science Campaign on the Jezero Crater Floor

“…The Alfalfa abrasion patch revealed white feldspar laths and pyroxene grains with possible olivine and quartz (Figure 20d). Evidence for aqueous alteration was less abundant than in previous abrasion patches but included detection of Fe oxides, carbonate, and possibly phyllosilicates, chlorite, phosphate, and perchlorate, as well as low concentrations of organic matter (Corpolongo et al., 2023; Sharma et al., 2022). Overall, Alfalfa was compositionally consistent with a basaltic andesite composition (Udry et al., 2023; Wiens et al., 2022) and, while strongly oxidized (Horgan et al., 2022), is otherwise the least aqueously altered abrasion from the campaign.…”

“…Like in the Guillaumes and Bellegarde abrasion patches, the brown‐toned materials in the Dourbes abrasion patch were associated with Fe‐rich phases. Other alteration phases identified were sulfate, carbonate, and amorphous silicate, in addition to organics that did not have any apparent correlation with texture (Corpolongo et al., 2023; Sharma et al., 2022). The texture, mineralogy, and bulk chemistry of Dourbes was consistent with Brac and the Bastide member representing a cumulate igneous rock formed as olivine crystals settle in a slowly cooling lava body, with subsequent crystallization of pyroxene and plagioclase in the interstitial regions (e.g., Farley et al., 2022; Liu et al., 2022).…”

“…Lighter‐toned patches again corresponded to secondary phases such as Mg and Ca sulfate, carbonate, and other hydrated phases. Organics were detected, some in association with sulfate phases (Corpolongo et al., 2023; Sharma et al., 2022). Purple‐toned coatings, observed at all previous sampling workspaces, were also observed on the natural surfaces of the rocks at Issole.…”

“…In the crater floor targets observed by SHERLOC, significant Raman signatures were rare; however, fluorescence measurements revealed strong indications for aromatic compounds. Abraded targets within the Máaz formation revealed the strongest fluorescence signal, while natural surface Máaz and abraded Séítah targets were comparable in signal strength (Sharma et al, 2022). Below we summarize the fluorescence observations for the Máaz and Séítah formations; please see Text S3 in Supporting Information S1 for an overview of the results from each target.…”

Samples Collected From the Floor of Jezero Crater With the Mars 2020 Perseverance Rover

“…The fluorescence spectra may be attributed to aromatic organic compounds with a fairly low average abundance, comparable to detections in some martian meteorites (e.g., Koike et al., 2020; Jaramillo et al., 2019; Steele et al., 2012, 2016, 2018, 2022). The most significant difference in fluorescence signals between the two formations is the close to order of magnitude more detections in Máaz versus Séítah (see Sharma, Beegle, et al., 2022; Sharma, Roppel, et al., 2022). The 335–350 nm feature is observed in all targets while the fluorescence doublet at 305 and 325 nm is only detected in the Bellegarde and Quartier targets, in which it is associated with sulfates, and the 290 and 330 nm features are found associated with carbonates and silicates.…”