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

Excess Freshwater Outflow from the Black Sea-Lake during Glacial and Deglacial Periods and Delayed Entry of Marine Water in the Early Holocene Require Evolving Sills

The Black Sea becomes periodically isolated from the global ocean during each glacial period. This occurs when the elevation of the global ocean is lower than the Bosporus sill, putting a stop to inflow of salt water to the Black Sea. This phenomenon allows the Black Sea to evolve from a marine environment to a freshwater one. It is also evident that the depth of the Bosporus sill does not remain at the same elevation, and instead is dynamic. The sill becomes filled with sediments during periods of its sub-aerial exposure but is subsequently eroded to its bedrock during periods of outflow from the Black Sea-Lake to the global ocean. This interpretation comes from the observations that during the last glacial period, the Black Sea-Lake was in a positive hydrological balance, fresh, and predominantly outflowing to the global ocean over a deep Bosporus sill, at approximately 80 meters below sea level (mbsl). It is highly likely that there were brief periods when the lake froze and the outflow suspended, such as during the extreme stadial conditions associated with the North Atlantic iceberg-discharge Heinrich Event 2 (HE 2) at ~24 kyr before present, when there is also no evident carbonate accumulation in stalagmites that receive water from evaporated Black Sea surface water. Upon the onset of deglaciation, large floods originating from the Fennoscandinavian Ice Sheet and the Alps, delivered meltwater so as to fully ventilate the Black Sea-Lake and even potentially replace all of the water in the basin. These floods occurred near the time of the deglacial iceberg-discharge Heinrich Event 1 (HE 1 at ~17 kyr before present), and left pulses of red-colored sediment everywhere on the western half of the Black Sea basin

The Organics of Mars

International audienceOur understanding of organic matter on Mars has evolved from presumed ‘missing organic molecules’ based on Viking data to a robust library of organic molecules detected over the last decade by the SAM (Sample Analysis at Mars) instrument suite onboard the Mars Science Laboratory (MSL) rover, as well as from studies of Mars meteorites. Additionally, recent findings by the Perseverance rover suggest the possibility of simple organics in data from the SHERLOC (Scanning Habitable Environments with Raman and Luminescence for Organics and Chemicals) fluorescence and Raman spectrometer. Here, we explore the current state of knowledge of organics on Mars from the perspective of in situ characterization with landed instruments, and the potential for new leaps in that knowledge with Mars Sample Return.MSL detections of organics in Gale crater mudstone and sandstones include chlorohydrocarbons up to 300 ppbw; small aliphatic, aromatic, and, sulfur-containing compounds (at 0.1-10 ppmw detections) potentially originating from macromolecular organics and long-chain alkanes from C10 to C12. Total abundance of C is likely higher than individual molecular detections and on the order of 100’s of ppmw. The recent TMAH wet chemistry experiment liberated macromolecular organics, resulting in the detection of one to two-ring aromatic compounds, benzoic acid methyl ester, and benzothiophene. All these detections confirmed the presence of organics in the Martian subsurface, despite exposure to ionizing radiation for at least 80 My.More recent findings from the SHERLOC instrument onboard the Mars2020 rover include fluorescence and Raman spectra that may be consistent with one- and two-ring organic molecules, although other inorganic sources for the spectra are possible.The next-generation instruments onboard the ExoMars rover (Raman, MicrOmega spectrometer and MOMA chemical analyzer), combined with a 2-meter drill, will enable investigation of better protected subsurface samples. The two current in situ organics detection techniques are quite different, but Mars Sample Return in the mid-2030s would provide the first groundtruth of these data, enable the search for other organic molecules that are not detectable by in situ instrumentation, and address fundamental outstanding questions about the origin of organics on Mars

The Organics of Mars

International audienceOur understanding of organic matter on Mars has evolved from presumed ‘missing organic molecules’ based on Viking data to a robust library of organic molecules detected over the last decade by the SAM (Sample Analysis at Mars) instrument suite onboard the Mars Science Laboratory (MSL) rover, as well as from studies of Mars meteorites. Additionally, recent findings by the Perseverance rover suggest the possibility of simple organics in data from the SHERLOC (Scanning Habitable Environments with Raman and Luminescence for Organics and Chemicals) fluorescence and Raman spectrometer. Here, we explore the current state of knowledge of organics on Mars from the perspective of in situ characterization with landed instruments, and the potential for new leaps in that knowledge with Mars Sample Return.MSL detections of organics in Gale crater mudstone and sandstones include chlorohydrocarbons up to 300 ppbw; small aliphatic, aromatic, and, sulfur-containing compounds (at 0.1-10 ppmw detections) potentially originating from macromolecular organics and long-chain alkanes from C10 to C12. Total abundance of C is likely higher than individual molecular detections and on the order of 100’s of ppmw. The recent TMAH wet chemistry experiment liberated macromolecular organics, resulting in the detection of one to two-ring aromatic compounds, benzoic acid methyl ester, and benzothiophene. All these detections confirmed the presence of organics in the Martian subsurface, despite exposure to ionizing radiation for at least 80 My.More recent findings from the SHERLOC instrument onboard the Mars2020 rover include fluorescence and Raman spectra that may be consistent with one- and two-ring organic molecules, although other inorganic sources for the spectra are possible.The next-generation instruments onboard the ExoMars rover (Raman, MicrOmega spectrometer and MOMA chemical analyzer), combined with a 2-meter drill, will enable investigation of better protected subsurface samples. The two current in situ organics detection techniques are quite different, but Mars Sample Return in the mid-2030s would provide the first groundtruth of these data, enable the search for other organic molecules that are not detectable by in situ instrumentation, and address fundamental outstanding questions about the origin of organics on Mars

The power of paired proximity science observations : Co-located data from SHERLOC and PIXL on Mars

We present a synthesis of PIXL elemental data and SHERLOC Raman spectra collected on two targets investigated by the Perseverance rover during the first year of its exploration of Jezero Crater, Mars. The Bellegarde target (in the Máaz formation) and Dourbes target (in the Séítah formation) exhibit distinctive mineralogies that are an ideal case study for in situ analysis by SHERLOC and PIXL. Each instrument alone produces valuable data about the chemistry and spatial distribution of mineral phases at the sub-millimeter scale. However, combining data from both instruments provides a more robust interpretation that overcomes the limitations of either instrument, for example: 1) Detection of correlated calcium and sulfur in Bellegarde by PIXL is corroborated by the co-located detection of calcium sulfate by SHERLOC. 2) Detection of sodium and chlorine in Dourbes is consistent with either chloride or oxychlorine salts, but SHERLOC does not detect perchlorate or chlorate. 3) A Raman peak at 1120 cm−1 in Dourbes could be sulfate or pyroxene, but elemental abundances from PIXL at that location are a better match to pyroxene. This study emphasizes the importance of analyzing co-located data from both instruments together, to obtain a more complete picture of sub-millimeter-scale mineralogy measured in situ in Jezero crater, Mars, by the Perseverance rover.</p

THE PETROGENETIC HISTORY OF THE JEZERO CRATER DELTA FRONT FROM MICROSCALE OBSERVATIONS BY THE MARS 2020 PIXL INSTRUMENT

International audienceOn ~sol 370 of the Perseverance rover mission, the Mars 2020 Science Team completed its investigation of igneous units of the Jezero crater floor [1] and directed Perseverance to drive towards the topographic scarp that marks the interface between the crater floor and Jezero’s western delta. The “Delta Front Campaign” consisted of close-up investigation and sampling of lithologies located there.Here, we report on the major findings relevant to the provenance and diagenetic history of these lithologies deduced from measurements made by the Planetary Instrument for X-ray Lithochemistry (PIXL), a micro-focus X-ray fluorescence (XRF) microscope [2]. Data were collected from two sections at Cape Nukshak and Hawksbill Gap; outcrop and member names are from [3]. Lithologies are described here in order from base to top of each section

THE PETROGENETIC HISTORY OF THE JEZERO CRATER DELTA FRONT FROM MICROSCALE OBSERVATIONS BY THE MARS 2020 PIXL INSTRUMENT

International audienceOn ~sol 370 of the Perseverance rover mission, the Mars 2020 Science Team completed its investigation of igneous units of the Jezero crater floor [1] and directed Perseverance to drive towards the topographic scarp that marks the interface between the crater floor and Jezero’s western delta. The “Delta Front Campaign” consisted of close-up investigation and sampling of lithologies located there.Here, we report on the major findings relevant to the provenance and diagenetic history of these lithologies deduced from measurements made by the Planetary Instrument for X-ray Lithochemistry (PIXL), a micro-focus X-ray fluorescence (XRF) microscope [2]. Data were collected from two sections at Cape Nukshak and Hawksbill Gap; outcrop and member names are from [3]. Lithologies are described here in order from base to top of each section