Aqueous alteration processes in Jezero crater, Mars—implications for organic geochemistry

The Perseverance rover landed in Jezero crater, Mars, in February 2021. We used the Scanning Habitable Environments with Raman and Luminescence for Organics and Chemicals (SHERLOC) instrument to perform deep-ultraviolet Raman and fluorescence spectroscopy of three rocks within the crater. We identify evidence for two distinct ancient aqueous environments at different times. Reactions with liquid water formed carbonates in an olivine-rich igneous rock. A sulfate-perchlorate mixture is present in the rocks, which probably formed by later modifications of the rocks by brine. Fluorescence signatures consistent with aromatic organic compounds occur throughout these rocks and are preserved in minerals related to both aqueous environments

Organomineralization of Microbialites from Storr\u27s Lake, San Salvador Island, Bahamas: Calcium, Carbon, and Oxygen Stable Isotope Analysis

Studying the isotopic composition and mineralogy of modern microbialites provides us with the key to interpreting the formation processes and environments of ancient microbialites. Growing in the hypersaline and turbid Storr\u27s Lake (SL) on San Salvador Island in the Bahamas are microbialites with low levels of photosynthesis and high levels of sulfate reduction-in contrast to many of their modern counterparts. Living planktonic, motile microorganisms and suspended algal and bacterial debris create the high turbidity of the shallow lake (\u3c2m) and rapidly attenuate sunlight in the water column. Microbialites were collected at both deep (depth \u3e60cm) and shallow (depth \u3c60cm) parts of SL in January 2016. SL had a conductivity 1.2 x seawater, pH ~8.4, and little variation in major cations. The water was more supersaturated with respect to calcite, aragonite, and dolomite than seawater. Carbon (C) isotopes of SL microbialite samples show both photosynthesis (evidenced by high C isotope values) and extracellular organic matter degradation (evidenced by low C isotope values in other samples) controlling organomineralization. This agrees with previous data which found both phototropic and heterotrophic bacterial taxa. Oxygen (O) isotopes are relatively consistent between microbialite sublayers and show an evaporative signature for SL. Microbe metabolisms interact with the larger environment of SL to precipitate carbonate within microenvironments of the microbial mats. Both high-Mg calcite (HMC) and aragonite are found within some of the microbialites leading to the hypothesis that the organomineralization process involves a step where HMC transforms to aragonite. The mineralogy of shallow and deep water samples will be compared to test the hypothesis that the transition from HMC to aragonite is only found in SL microbialites growing in water deeper than 60cm (at time of collection). New calcium (Ca) stable isotope analyses from the TIMS using a 42Ca-43Ca double spike will be presented to provide evidence to support (or refute) this hypothesis since we expect differences in mineralogy to be the primary control on Ca isotope signatures. These new results will be compared to other modern and ancient carbonate systems to better understand organomineralization processes and how they fractionate Ca isotopes

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

International audienceThe Mars 2020 Perseverance rover landed in Jezero crater on 18 February 2021. After a 100-sol period of commissioning and the Ingenuity Helicopter technology demonstration, Perseverance began its first science campaign to explore the enigmatic Jezero crater floor, whose igneous or sedimentary origins have been much debated in the scientific community. This paper describes the campaign plan developed to explore the crater floor's Máaz and Séítah formations and summarizes the results of the campaign between sols 100-379. By the end of the campaign, Perseverance had traversed more than 5 km, created seven abrasion patches, and sealed nine samples and a witness tube. Analysis of remote and proximity science observations show that the Máaz and Séítah formations are igneous in origin and composed of five and two geologic members, respectively. The Séítah formation represents the olivine-rich cumulate formed from differentiation of a slowly cooling melt or magma body, and the Máaz formation likely represents a separate series of lava flows emplaced after Séítah. The Máaz and Séítah rocks also preserve evidence of multiple episodes of aqueous alteration in secondary minerals like carbonate, Fe/Mg phyllosilicates, sulfates, and perchlorate, and surficial coatings. Post-emplacement processes tilted the rocks near the Máaz-Séítah contact and substantial erosion modified the crater floor rocks to their present-day expressions. Results from this crater floor campaign, including those obtained upon return of the collected samples, will help to build the geologic history of events that occurred in Jezero crater and provide time constraints on the formation of the Jezero delta. Plain Language Summary The Mars 2020 Perseverance rover, along with the Ingenuity Helicopter technology demonstration, landed in Jezero crater, Mars on 18 February 2021. Here, we detail results from the first science campaign of the mission, the purpose of which was to explore the enigmatic Jezero crater floor. By the end of the campaign, Perseverance traversed more than 5 km, created seven abrasion patches, SUN ET AL

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

The Mars 2020 Perseverance rover landed in Jezero crater on 18 February 2021. After a 100‐sol period of commissioning and the Ingenuity Helicopter technology demonstration, Perseverance began its first science campaign to explore the enigmatic Jezero crater floor, whose igneous or sedimentary origins have been much debated in the scientific community. This paper describes the campaign plan developed to explore the crater floor's Máaz and Séítah formations and summarizes the results of the campaign between sols 100–379. By the end of the campaign, Perseverance had traversed more than 5 km, created seven abrasion patches, and sealed nine samples and a witness tube. Analysis of remote and proximity science observations show that the Máaz and Séítah formations are igneous in origin and composed of five and two geologic members, respectively. The Séítah formation represents the olivine‐rich cumulate formed from differentiation of a slowly cooling melt or magma body, and the Máaz formation likely represents a separate series of lava flows emplaced after Séítah. The Máaz and Séítah rocks also preserve evidence of multiple episodes of aqueous alteration in secondary minerals like carbonate, Fe/Mg phyllosilicates, sulfates, and perchlorate, and surficial coatings. Post‐emplacement processes tilted the rocks near the Máaz‐Séítah contact and substantial erosion modified the crater floor rocks to their present‐day expressions. Results from this crater floor campaign, including those obtained upon return of the collected samples, will help to build the geologic history of events that occurred in Jezero crater and provide time constraints on the formation of the Jezero delta