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  • Lunar and Planetary Science and Exploration  (2)
  • Geologic Sediments
  • Review article
  • 2010-2014  (3)
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  • 1
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    Ancient aqueous environments at Endeavour crater, Mars (2014)
    American Association for the Advancement of Science (AAAS)
    Details
    Publication Date: 2014-01-25
    Description: Opportunity has investigated in detail rocks on the rim of the Noachian age Endeavour crater, where orbital spectral reflectance signatures indicate the presence of Fe(+3)-rich smectites. The signatures are associated with fine-grained, layered rocks containing spherules of diagenetic or impact origin. The layered rocks are overlain by breccias, and both units are cut by calcium sulfate veins precipitated from fluids that circulated after the Endeavour impact. Compositional data for fractures in the layered rocks suggest formation of Al-rich smectites by aqueous leaching. Evidence is thus preserved for water-rock interactions before and after the impact, with aqueous environments of slightly acidic to circum-neutral pH that would have been more favorable for prebiotic chemistry and microorganisms than those recorded by younger sulfate-rich rocks at Meridiani Planum.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Arvidson, R E -- Squyres, S W -- Bell, J F 3rd -- Catalano, J G -- Clark, B C -- Crumpler, L S -- de Souza, P A Jr -- Fairen, A G -- Farrand, W H -- Fox, V K -- Gellert, R -- Ghosh, A -- Golombek, M P -- Grotzinger, J P -- Guinness, E A -- Herkenhoff, K E -- Jolliff, B L -- Knoll, A H -- Li, R -- McLennan, S M -- Ming, D W -- Mittlefehldt, D W -- Moore, J M -- Morris, R V -- Murchie, S L -- Parker, T J -- Paulsen, G -- Rice, J W -- Ruff, S W -- Smith, M D -- Wolff, M J -- New York, N.Y. -- Science. 2014 Jan 24;343(6169):1248097. doi: 10.1126/science.1248097.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Earth and Planetary Sciences, Washington University in Saint Louis, St. Louis, MO 63130, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/24458648" target="_blank"〉PubMed〈/a〉
    Keywords: Bacteria ; *Exobiology ; Extraterrestrial Environment/*chemistry ; Geologic Sediments ; Hydrogen-Ion Concentration ; *Mars ; Silicates/analysis/chemistry ; Spacecraft ; Sulfates/chemistry ; *Water
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
    Published by American Association for the Advancement of Science (AAAS)
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    PAPER CURRENT
  • 2
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    Amorphous Phases on the Surface of Mars (2014)
    In:  CASI
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    Publication Date: 2019-07-19
    Description: Both primary (volcanic/impact glasses) and secondary (opal/silica, allophane, hisingerite, npOx, S-bearing) amorphous phases appear to be major components of martian surface materials based on orbital and in-situ measurements. A key observation is that whereas regional/global scale amorphous components include altered glass and npOx, local scale amorphous phases include hydrated silica/opal. This suggests widespread alteration at low water-to-rock ratios, perhaps due to snow/ice melt with variable pH, and localized alteration at high water-to-rock ratios. Orbital and in-situ measurements of the regional/global amorphous component on Mars suggests that it is made up of at least three phases: npOx, amorphous silicate (likely altered glass), and an amorphous S-bearing phase. Fundamental questions regarding the composition and the formation of the regional/global amorphous component(s) still remain: Do the phases form locally or have they been homogenized through aeolian activity and derived from the global dust? Is the parent glass volcanic, impact, or both? Are the phases separate or intimately mixed (e.g., as in palagonite)? When did the amorphous phases form? To address the question of source (local and/or global), we need to look for variations in the different phases within the amorphous component through continued modeling of the chemical composition of the amorphous phases in samples from Gale using CheMin and APXS data. If we find variations (e.g., a lack of or enrichment in amorphous silicate in some samples), this may imply a local source for some phases. Furthermore, the chemical composition of the weathering products may give insight into the formation mechanisms of the parent glass (e.g., impact glasses contain higher Al and lower Si [30], so we might expect allophane as a weathering product of impact glass). To address the question of whether these phases are separate or intimately mixed, we need to do laboratory studies of naturally altered samples made up of mixed phases (e.g., palagonite) and synthetic single phases to determine their short-range order structures and calculate their XRD patterns to use in models of CheMin data. Finally, to address the timing of the alteration, we need to study rocks on the martian surface of different ages that may contain glass (volcanic or impact) with MSL and future rovers to better understand how glass alters on the martian surface, if that alteration mechanism is universal, and if alteration spans across long periods of time or if there is a time past which unaltered glass remains.
    Keywords: Lunar and Planetary Science and Exploration
    Type: JSC-CN-31338 , International Conference on Mars; Jul 14, 2014 - Jul 18, 2014; Pasadena, CA; United States
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 3
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    Evidence for a Noachian-Aged Ephemeral Lake in Gusev Crater, Mars (2014)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: Gusev crater was selected as the landing site for the Spirit rover because of the likelihood that it contained an ancient lake. Although outcrops rich in Mg-Fe carbonate dubbed Comanche were discovered in the Noachian-aged Columbia Hills, they were inferred to result from volcanic hydrothermal activity. Spirit encountered other mineral and chemical indicators of aqueous activity, but none was recognized as definitive evidence for a former lake in part because none was associated with obvious lacustrine sedimentary deposits. However, water discharge into Martian crater basins like Gusev may have been episodic, producing only small amounts of sediment and shallow ephemeral lakes. Evaporative precipitation from such water bodies has been suggested as a way of producing the Mg- and Fe-rich carbonates found in ALH84001 and carbonates and salts in some nakhlites a hypothesis we examine for the Comanche carbonate.
    Keywords: Lunar and Planetary Science and Exploration
    Type: JSC-CN-30542 , Lunar and Planetary Science Conference; Mar 17, 2014 - Mar 21, 2014; The Woodlands, TX; United States
    Format: application/pdf
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    NASA TECHNICAL REPORTS
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