A Mars-analog sulfate mineral, mirabilite, preserves biosignatures

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Sulfur plays a major role in martian geochemistry and sulfate minerals are important repositories of water. However, their hydration states on Mars are poorly constrained. Therefore, understanding the hydration and distribution of sulfate minerals on Mars is important for understanding its geologic, hydrologic, and atmospheric evolution as well as its habitability potential. NASA's Perseverance rover is currently exploring the Noachian‐age Jezero crater, which hosts a fan‐delta system associated with a paleolake. The crater floor includes two igneous units (the Séítah and Máaz formations), both of which contain evidence of later alteration by fluids including sulfate minerals. Results from the rover instruments Scanning Habitable Environments with Raman and Luminescence for Organics and Chemistry and Planetary Instrument for X‐ray Lithochemistry reveal the presence of a mix of crystalline and amorphous hydrated Mg‐sulfate minerals (both MgSO4·[3–5]H2O and possible MgSO4·H2O), and anhydrous Ca‐sulfate minerals. The sulfate phases within each outcrop may have formed from single or multiple episodes of water activity, although several depositional events seem likely for the different units in the crater floor. Textural and chemical evidence suggest that the sulfate minerals most likely precipitated from a low temperature sulfate‐rich fluid of moderate pH. The identification of approximately four waters puts a lower constraint on the hydration state of sulfate minerals in the shallow subsurface, which has implications for the martian hydrological budget. These sulfate minerals are key samples for future Mars sample return.

Section: Discussionmentioning

confidence: 99%

Evidence of Sulfate‐Rich Fluid Alteration in Jezero Crater Floor, Mars

Siljeström,

Czaja,

Corpolongo

et al. 2024

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“…Such rock‐hosted microenvironments are particularly favorable settings for chemolithotrophic and endolithic microbiota that are widely considered plausible metabolic strategics for the putative martian biosphere (Onstott et al., 2019). Furthermore, sulfates are known to have high biosignature preservation potential and may entomb organic materials and fluid inclusions facilitating the characterization of these habitable microenvironments (Gill et al., 2023; Natalicchio et al., 2021).…”

Section: Discussionmentioning

confidence: 99%

Sedimentology and Stratigraphy of the Shenandoah Formation, Western Fan, Jezero Crater, Mars

Stack,

Ives,

Gupta

et al. 2024

Sedimentary fans are key targets of exploration on Mars because they record the history of surface aqueous activity and habitability. The sedimentary fan extending from the Neretva Vallis breach of Jezero crater's western rim is one of the Mars 2020 Perseverance rover's main exploration targets. Perseverance spent ∼250 sols exploring and collecting seven rock cores from the lower ∼25 m of sedimentary rock exposed within the fan's eastern scarp, a sequence informally named the “Shenandoah” formation. This study describes the sedimentology and stratigraphy of the Shenandoah formation at two areas, “Cape Nukshak” and “Hawksbill Gap,” including a characterization, interpretation, and depositional framework for the facies that comprise it. The five main facies of the Shenandoah formation include: laminated mudstone, laminated sandstone, low‐angle cross stratified sandstone, thin‐bedded granule sandstone, and thick‐bedded granule‐pebble sandstone and conglomerate. These facies are organized into three facies associations (FA): FA1, comprised of laminated and soft sediment‐deformed sandstone interbedded with broad, unconfined coarser‐grained granule and pebbly sandstone intervals; FA2, comprised predominantly of laterally extensive, soft‐sediment deformed laminated, sulfate‐bearing mudstone with lenses of low‐angle cross‐stratified and scoured sandstone; and FA3, comprised of dipping planar, thin‐bedded sand‐gravel couplets. The depositional model favored for the Shenandoah formation involves the transition from a sand‐dominated distal alluvial fan setting (FA1) to a stable, widespread saline lake (FA2), followed by the progradation of a river delta system (FA3) into the lake basin. This sequence records the initiation of a relatively long‐lived, habitable lacustrine and deltaic environment within Jezero crater.

“…Microorganisms and organic compounds can be entrapped as solids and within fluid inclusions as sulfate minerals grow quickly. Cells of archaea, bacteria, and algae as well as fungi, pollen, and insects have been found in sulfate minerals (i.e., Benison & Karmanocky, 2014; Gill et al., 2023). In addition, organic compounds such as beta‐carotene and glycerine have also been detected (Benison & Karmanocky, 2014; Gill et al., 2023).…”

Section: Discussionmentioning

confidence: 99%

“…Cells of archaea, bacteria, and algae as well as fungi, pollen, and insects have been found in sulfate minerals (i.e., Benison & Karmanocky, 2014; Gill et al., 2023). In addition, organic compounds such as beta‐carotene and glycerine have also been detected (Benison & Karmanocky, 2014; Gill et al., 2023). When trapped within a fluid inclusion, cells and organic compounds are in a microhabitat that may provide a host environment for long geological time periods (i.e., Lowenstein et al., 2011; Schreder‐Gomes et al., 2022).…”

Section: Discussionmentioning

confidence: 99%

“…For this study, we focus on the petrography of the abrasion patches Berry Hollow and Uganik Island to describe depositional and diagenetic features at the cm–sub‐mm scale. We pay particular attention to the sulfate mineral components of these rocks due to their potential to preserve biosignatures (i.e., Benison, 2019a; Gill et al., 2023; Longo et al., 2019; Martinez‐Frias et al., 2006; Sharma et al., 2023). The wider context of depositional history, stratigraphic context, and diagenetic features can be found in other recent papers (i.e., Broz et al., 2023; Dehouck et al., 2023; Farley & Stack, 2023; Kalucha et al., 2023; Stack et al., 2023).…”

Section: Methods and Approachmentioning

confidence: 99%

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Depositional and Diagenetic Sulfates of Hogwallow Flats and Yori Pass, Jezero Crater: Evaluating Preservation Potential of Environmental Indicators and Possible Biosignatures From Past Martian Surface Waters and Groundwaters

Benison,

Gill,

Sharma

et al. 2024

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The Mars 2020 Perseverance rover has examined and sampled sulfate‐rich clastic rocks from the Hogwallow Flats member at Hawksbill Gap and the Yori Pass member at Cape Nukshak. Both strata are located on the Jezero crater western fan front, are lithologically and stratigraphically similar, and have been assigned to the Shenandoah formation. In situ analyses demonstrate that these are fine‐grained sandstones composed of phyllosilicates, hematite, Ca‐sulfates, Fe‐Mg‐sulfates, ferric sulfates, and possibly chloride salts. Sulfate minerals are found both as depositional grains and diagenetic features, including intergranular cement and vein‐ and vug‐cements. Here, we describe the possibility of various sulfate phases to preserve potential biosignatures and the record of paleoenvironmental conditions in fluid and solid inclusions, based on findings from analog sulfate‐rich rocks on Earth. The samples collected from these outcrops, Hazeltop and Bearwallow from Hogwallow Flats, and Kukaklek from Yori Pass, should be examined for such potential biosignatures and environmental indicators upon return to Earth.