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David J. Des Marais NASA Ames Research Center

Preservation of Evidence of Ancient Environments and Life on Mars. Mars today. Early Mars ?. David J. Des Marais NASA Ames Research Center. Preservation: topics. Noachian-Hesperian environments & processes Persistence of ancient aqueous environments

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David J. Des Marais NASA Ames Research Center

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  1. Preservation of Evidence of Ancient Environments and Life on Mars Mars today Early Mars ? David J. Des Marais NASA Ames Research Center

  2. Preservation: topics Noachian-Hesperian environments & processes Persistence of ancient aqueous environments Nature of deposits in Noachian aqueous environments Phyllosilicate deposits & organic matter concentrations Preservation potential of the four “finalist” MSL sites

  3. Importance of Age

  4. Meridiani Planum and the Global Hydrology of Mars Importance of Elevation B A B A detected evaporite deposits Andrews-Hanna et al. (2007)

  5. Stream Systems Stepinski & Luo, LPSC41, 2010

  6. Apollinaris Patera (volcano) Northern Lowlands Southern Highlands x Ma’Adim Vallis Gusev Crater ~180 km diameter

  7. Orbiter view (MRO HiRISE)Husband Hill andInnerBasinground view(MER Pancam)

  8. Importance of Age and Depth in Crust

  9. Oyama Crater & Mawrth Vallis bedrock exposures have a light tone; some dark-toned materials in this area are also bedrock (commonly but not always a caprock above light-toned rocks) “Mawrth mouth” Mawrth Vallis regolith covers bedrock in the ‘intermediate gray’ areas – some of that regolith is considered to be eolian-deposited dust and/or crusted eolian dust (e.g., Presley and Arvidson 1987) candidate MSL field site note Oyama formed in light-toned bedrock Oyama (107 km diam) Mawrth Vallis MGS MOC red wide angle mosaic Mawrth Vallis The name “Oyama” was approved by the IAU 26 March 2010. Named for Vance I. Oyama, Viking Gas Exchange Experiment PI. MSL Science Team Field Site Discussions – Mawrth Note: Candidate landing ellipse size and shape is approximate. 10

  10. Pilbara Craton and Hamersley Range, W. Australia

  11. Mars Global Surveyor MOLA Topography

  12. Marine Chlorophyll Abundances (LowModerateHigh)

  13. Key Factors: Paleo-productivity Sedimentary redox Mineralogy Lithification Later alteration

  14. Pilbara Craton and Hamersley Range, W. Australia

  15. Preservation of Evidence about Ancient Mars Noachian-Hesperian environments and processes Persistence of ancient aqueous environments Noachian deposits in aqueous environments Phyllosilicate-rich deposits and organic matter contents Preservation potential of the four “finalist” MSL sites Age of deposits: mid-Noachian to early Hesperian Water persistence: effects of elevation and geologic age Allochthonous vs autochthonous phyllosilicates Redox state of deposit Lithification: rate and extent

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