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Orbital Context and In Situ Observations of Nili Fossae Olivine-Carbonate
  • +15
  • Adrian Brown,
  • Roger Wiens,
  • Sylvestre Maurice,
  • Patrick Pinet,
  • Lucia Mandon,
  • Stephane Le Mouelic,
  • Lisa Mayhew,
  • Arya Udry,
  • Briony Horgan,
  • Nathalie Turenne,
  • Fred Calef,
  • Edward Cloutis,
  • Thierry Fouchet,
  • Clément Royer,
  • María-Paz Zorzano,
  • Eleni Ravanis,
  • Sarah Fagents,
  • Alberto Fairén
Adrian Brown
Self Employed

Corresponding Author:[email protected]

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Roger Wiens
Space Science and Applications
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Sylvestre Maurice
IRAP, CNRS, Université de Toulouse, UPS-OMP
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Patrick Pinet
Institut de Recherche en Astrophysique et Planétologie (IRAP)
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Lucia Mandon
LESIA, Observatoire de Paris, Université PSL, CNRS, Sorbonne Université, Université de Paris
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Stephane Le Mouelic
LPG Nantes, UMR 6112, CNRS, OSUNA, Université de Nantes
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Lisa Mayhew
University of Colorado at Boulder
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Arya Udry
University of Nevada Las Vegas
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Briony Horgan
Purdue University
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Nathalie Turenne
University of Winnipeg
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Fred Calef
Jet Propulsion Laboratory
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Edward Cloutis
University of Winnipeg
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Thierry Fouchet
LESIA, Observatoire de Paris, Université PSL, CNRS, Sorbonne Université, Université de Paris
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Clément Royer
LESIA, Observatoire de Paris, Université PSL, CNRS, Sorbonne Université, Université de Paris
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María-Paz Zorzano
Centro de Astrobiología
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Eleni Ravanis
University of Hawaii at Manoa
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Sarah Fagents
Univ Hawaii
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Alberto Fairén
Centro de Astrobiología (CSIC-INTA), Madrid, Spain, and Dept. of Astronomy, Cornell University
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Perseverance landed at the Octavia E. Butler landing site next to the Séítah dune region in Jezero crater on 18 February 2021, in close proximity to the largest exposed carbonate deposit on Mars. These carbonate signatures have been shown to be associated with the strongest olivine signatures at Jezero crater (Goudge+ 2015, Brown+ 2020). Alteration of olivine can lead to carbonate+H2 production, an energy source for microbes (Mayhew+, 2013). The question of the origin of the olivine-carbonate unit represents both an opportunity and a challenge for the rover mission and future sample return efforts. Carbonate The landing site is not near the region of carbonate detections (Figure 1), however the rover’s westward traverse will take us over the carbonates on approach to the crater rim. No reliable indications of the 2.5 μm carbonate band have yet been convincingly detected by the SCAM VISIR instrument. Olivine Studies of the olivine-carbonate unit concluded the olivine is relatively Fe-rich and coarse grained (mm: Poulet+ 2007, Clenet+ 2013). The strongest in-situ olivine signatures are found in dune material analysed by LIBS/VISIR (Beyssac+ Mandon+ this conf). This grain size characterization work may be used to investigate the interaction of olivine with water and CO2 (Escamilla-Roa+ 2020). These surface-gas processes are enhanced when olivine is in fine grain form. Ash dispersal modeling is ongoing (Ravanis+ this conf) to determine the range different sized ash particles could have traveled on ancient Mars. We cannot directly compare the 1 μm band for CRISM and VISIR, so we developed a new method that measures the curvature of three points on the absorption bands to assess their relative Fo# shifts and applied it to both datasets. Lab spectroscopy will be used to assess spectral variations with composition versus grain size. Two key factors driving the Fo# are mantle composition and melt temperature. Brown+ (2020) estimated a range of Fo44-65 for the most redshifted olivine observed by CRISM. McGetchin+Smythe (1978) showed that an Fe-rich mantle composition would produce highly viscous lavas and suggested an upper bound of Fo70 for olivine. Understanding the astrobiological potential of the olivine-carbonate unit is a priority of M2020 (Farley+ 2020) and we will speculate on potential formation models in this contribution.