Mawrth Rocks ! ( W itnesses of the early Mars habitability, biosignature and climate)

1. Mawrth Rocks ! (Witnesses of the early Mars habitability, biosignature and climate) 3rd Mars 2020 Landing Site Meeting / February 8-10, 2017 NOTE ADDED BY JPL WEBMASTER: This content has not been approved or adopted by, NASA, JPL, or the California Institute of Technology. This document is being made available for information purposes only, and any views and opinions expressed herein do not necessarily state or reflect those of NASA, JPL, or the California Institute of Technology.

2. Site Refresher: Global & regional context • Located at boundary of cratered Noachian terrain and northern lowlands • OMEGA & CRISM discovered extended (vertically and horizontally) deposits of very diverse and abundant phyllosilicates associated to layered terrains + other aqueous phases (Si-OH phases, sulfates) • Numerous studies (40+ peer-reviewed papers including several Science and Nature papers) • Proposed for the human missions with exciting resources (largest clay content on Mars) Note from JPL Webmaster: Video not uploaded

3. Site Refresher: Early Noachian to Hesperian Loizeau et al. (2012) MAWRTH VALLIS UNITS Des Marais Opportunity tosample rocks from the deep Noachian up through the global transition into the Hesperian

4. Site Refresher: Mineralogy

5. Site Refresher: Mineralogy Al-phyllosilicates/Si-OH Fe2+ material Fe3+/Mg-smectites See next presentation (J. Bishop) for detailed mineralogy

6. Site Refresher: Stratigraphy Al‐phyllosilicates and hydrated silica Mafic Cap Local Sulfate deposits Ferrous horizon Vertical exageration Fe/Mg phyllo • Testable hypotheses: • 1- Fe/Mg smectites may be representative of the global Noachian Martian clays possibly formed during hundred millions years • 2- Environment(s) with sustainable water • 3- Evolutionary pathways translated into the various types of minerals

7. Site Refresher: Geological features 10 m => Sedimentary process(es)

8. Site Refresher: Geological features 10 m Fluvial activities => Local aqueous processes and environments (rivers, ponds, wetlands, lakes, etc) => Sedimentary process(es)

9. Site Refresher: Geological features 10 m Fluvial activities => Local aqueous processes and environments (rivers, ponds, wetlands, lakes, etc) => Sedimentary process(es)

10. Site Refresher: Geological features Fe-clays Rugged and eroded (inverted craters) texture, meter-scale polygonal cracks => Variation with time of deposition processes (sub) meter-scale polygonal cracks (sub) meter-scale polygonal cracks

11. Site Refresher: Geological features Filled Fractures/Veins 100 m increasing erosion • Hydrothermal process followed by mineralization

12. Site Refresher: Unique attributes • Water history • Probing past climate • Pre-biotic chemistry • Preservation of biosignatures

13. Water history Early to middle Noachian • Phase 1 • Progressive deposition and alteration of sediments • Surface assemblage: Fe/Mg smectites + mica : • Moderate water rock ratio • Sustained aqueous activity • Low temperature alteration in marine environments and/or pedogenesis

14. Water history Middle to late Noachian • Phase 2 • Fluvial activities (erosion) + Fracturing • MawrthVallis outflow, valleys and channels on the plateau • Fractures in the clay unit

15. Water history Late Noachian/Early Hesperian • Phase 3 • Deposition of top section of Al-clays/Si-OH + Fluid circulation in fractures • Surface assemblage of top section: Kaolins, ferrous clays, sulfates, amorphous Si-phases: • Implies unique environment(s) • Consistent with period of warm and wet climate or localized acid leaching in a wetlands environment • Local precipitation of sulfates: • Extreme redox gradient: excellent source of energy for putative Martian microbes

16. Water history Early Hesperian (3.6 Ga) • Phase 4 • Mafic cap deposition • Probable volcanic/pyroclastic deposits • No more aqueous alteration • Preservation of clays and morphologic features (channels)

17. Water history Hesperian and Amazonian • Phase 5 • Wind erosion • the whole section is progressively and continuously exhumed • Fresh surfaces and deposits

18. Water history • Mawrth samples several stages of the aqueous alteration evolution of the early Mars • If life appears at one of these stages, Mars2020 will identify it in one of these samples • Phase 5 • Wind erosion • the whole section is progressively and continuously exhumed • Fresh surfaces and deposits

19. Site Refresher: Unique attributes • Complex water history • Probing past climate • Pre-biotic chemistry • Preservation of biosignatures

20. Probing past climate Fe/Mg - clays Al - clays 100 m • Al-clays over Fe/Mg-smectites sequence is common on Mars during this time period • Planetary event • Consistentwith long-term (~million years) leaching profiles in a wetter climate CRISM Carter et al. (2015)

21. Site Refresher: Unique attributes • Complex water history • Probing past climate • Pre-biotic chemistry • Preservation of biosignatures

22. Prebiotic => Biochemistry • Phyllosilicates provided convenient reaction surface (silicate sheets with charged surface) • Metal ions (especially Fe) in clay matrix couldhave been industrial catalysts and could have attracted nucleotides • Local aqueous environments such as soils and wetlands are recognized to be highly habitable - energy, water, nutrients, etc. • Redox reactions (reduced ferrous horizon) possibly catalyzed by microbe • Samples: • Any clay-bearing material (to search for organics, isotopic biosignatures, chirality) • Filled fractures (as mineral precipitation could have occurred under hydrothermal conditions) See next presentations (B. Horgan & D. Loizeau) for detailed discussion

23. Site Refresher: Unique attributes • Complex water history • Probing past climate • Pre-biotic Chemistry • Preservation of Biosignatures

24. Preservation of biosignatures • Long-term preservation ismost successful in phyllosilicate- and silica-bearing host rocks (impermeable barrier for biosignatures) • High clay content associated to sedimentary deposits in MV helps organic preservation • No evidence for illitization and no mixed layer clays at MV => Biosignatures, if any, were not degraded through thermal processing such as diagenesis • Thematerial that was buried below the dark cap unit and only recently exhumed could be of great interest Clay unit Capping unit

25. Landing site ellipse: here we should be ! Note from JPL Webmaster: Video not uploaded Wherever you land… there are astrobiological targets close by See next presentation (D. Loizeau) for detailed discussion & fun virtual tour

26. Unique Attractive Points Mineralogicallyverydiverse site => multiple forms of aqueous systems Lithologicallydiverse site that captures multiple environments => deposition, alteration, erosion, mineralization Both in-situ, ancient Noachian crustal bedrock and remobilized sediments Consistent with a paleosol sequence ending in a wetlands-like environment Reducing conditions, silica, very high clay content, capping unit=> high preservation potential Fresh surfaces (continuous erosion of clays) and no diagenetic overprinting Sample biosignatures in the habitable environment in which they were formed Sample rocks from the deep Noachian up through the global transition into the Hesperian A lot of surprises

27. Backup slides

28. Mawrth Rocks and Space Exploration • Mars space exploration has demonstrated that Mars geology and environment have drastically evolved along its first hundreds of millions years, as primarily recorded in the mineralogical diversity put into its geomorphological context. • Marshabitability has likely followed this evolution. The overarching goals of Mars2020, with the search for potential records of Mars habitable environments and potential bio-relics, requires to cover for as much as possible all steps of Mars early evolution, recorded in specific samples. • It is remarkable that Mars has uniquely preserved sites with such ancientrecords. • Marwth Vallis is the most promising one, as it enables, almost wherever Mars2020 will land, within the proposed ellipse, to access terrains exhibiting the full range of minerals and exciting geological features tracing the evolution of Mars environment/climate/history. • Most terrains of relevance have been exhumed recently, which, in addition to their specific character, optimize their preservation quality index. • Mawrth Vallis thus offers the best and unique opportunity to access and identify samples in which C-rich compounds of potential bio-relevance will be preserved and sampled. Des Marais

29. Aqueous Processes at Mawrth Vallis • Evidence for 100s of km expanse of phyllosilicate stratigraphy indicating large-scale aqueous events. • Observed stratigraphy suggests multiple forms of aqueous systems. • Evidence for intense alteration and possibly acidic leaching through presence of hydrated silica and kaolinite. • Consistent with period of warm and wet climate. • Evidence for sulfate formation and acidic leaching through presence of sulfates, salts, and acid-treated clays. • Consistent with low pH. • Evidence for active chemistry and changing redox potential due to presence of ferrous phase (Fe2+) on top of nontronite (Fe3+). • Implies unique aqueous environment, probably for a short period of time. • Consistent with microbial activity, hydrothermal activity, forced precipitation due to loss of water.

30. Aqueous Processes at Mawrth Vallis: Pre-biotic Chemistry • Phyllosilicate synthesis and reactions: • Nontronite, Fe-rich montmorillonite and glauconite/illite formation predicted for O2-free waters (Harder, 1988) e.g. early Earth and Mars. • Phyllosilicates may catalyze chemical reactions due to their surface acidity and by bringing together molecules on their surfaces (Pinnavaia, 1983). • Metal ions in clay matrix attract nucleotides and may have played a crucial role in the origin and early evolution of life (Odom et al. 1979; Lawless et al., 1985). • Clays and silica are good preservers of biosignatures: • If organics were present on early Mars, clay-rich sediments would be likely to trap these and then preserve them over time.

31. Why Mawrth is exciting landing site? • Mawrth Vallis is unique *across all of Mars* in having high phyllosilicate abundances. • Mawrth Vallis is unique *among the landing sites* in having Al-phyllosilicates (possibly indicating stronger alteration). • Lack of evidence for illitization due to diagenesis that may have occurred elsewhere on Mars and reduced biosignature preservation potential. • Multiple distinct mineralogies are accessible throughout the landing ellipse. • MSL would help resolve some questions about mineralogy: • Smectite versus chlorite • Jarosite versus acid-treated smectite • Sulfate or other hydrated salt • Ferrous material: chlorite, carbonate, other? • Mafic rock composition: pyroxene, feldspar, olivine • Mawrth Vallis offers the potential to link discoveries made by MSL to alteration processes acting across a very broad region.

32. Possible Formation Mechanisms • Clay deposits in sedimentary basin. • Expect strong connection between clays and rocks at basin. • Primarily chemical weathering produces smectites. • Pedogenesis in moist climate. • Typically produces secondary silica phases such as opal, plus kaolinite at the top of the column and smectite at the bottom. • In situ aqueous alteration of basaltic ash-fall. • Implies open body of water. • Consistent with bentonite formation. • Aqueous transport of sediments or impact ejecta. • Sediment mineralogy may be unrelated to rocks at basin. • Primarily physical weathering produces illites and siliceous sediments. • Hydrothermal alteration. • Liquid or frozen water mobilized by impact-induced system. • Cations introduced via hot volcanic fluids or steam.