Aqueous Alteration and Habitability in Nili Fossae

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Aqueous Alteration and Habitability in Nili Fossae

• J.F. Mustard, F. Poulet, N. Mangold, J-P.
  Bibring, R.E. Milliken, S. Pelkey, and L. Kanner

Habitability defined by water activity, nutrient
and energy availability Phyllosilicate alteration
in ancient terrains in association with
unaltered crust
Noachian crust enriched in low-Ca pyroxene
Noachian crust enriched in phyllosilicate
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Identification of Targets with OMEGA VNIR Data
Olivine Low-Ca Pyroxene Phyllosilicate

• Systematic mapping of mafic and aqueous minerals
• Detailed verification of aqueous detections
• Geologic context of major occurrences
• Noachian basement
• Delta deposits
• Layered material

b
6 Candidate sites evaluated a) Nili Fossae
Trough b) Nilosyrtis layered deposits c)
Eroded Noachian basement d) Delta deposit e)
Olivine-phyllosilicate f) Altered olivine
e
f
a
c
d
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Nili Fossae Trough

• Distinct phyllosilicate outcrops connected to
  geologic formations exposed in a sapping (?)
  channel
• Phyllosilicate in the distal portion of ejecta
  deposit showing lobate/textured morphology
• Adjacent unaltered basement and phyllosilicate gt
  chemical disequilibrium
• Hesperian volcanics of Syrtis Major sampling a
  critical time-stratigraphic marker and major
  lithology
• Noachian basement enriched in low-Ca pyroxene
  possibly sampling primary crust

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THEMIS VIS V02444003
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MOC E1200555
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MOC E1200555
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THEMIS VIS V14576022
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MOC R1403073
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• Topography -690 to -520 m
• Slopes 2-5 km length scale lt 2.5
• Thermal inertia gt 100 J m-2 s-0.5 K-1
• Albedo lt 0.25

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MOC M2101233
THEMIS VIS V10333012
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Nili Fossae TroughHabitability

• Water activity Nutrients Energy
• Phyllosilicate is a possible template for the
  origin of RNA-DNA and life
• Chemical sources of energy are critical

Pros Phyllosilicate in bedrock and ejecta
neutral pH, concentration and preservation of
organics chemical energy sources
Cons Ancient (preservation) Environment
from morphology complex
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• Nili Fossae region presents a number of high
  priority targets for MSL
• Numerous phyllosilicate-bearing outcrops
  representing several deposition/formation
  environments
• Trough site phyllosilicate adjacent/intimate
  with unaltered bedrock, distal ejecta deposits
  rich in clay, Syrtis Major lavas
• Trough site meets preliminary EDL, trafficability
  Planetary protection requirements
• Importance of phyllosilicate
• Preferential sequestration of organic carbon
• Formation in habitable environments with abundant
  energy sources and water

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-650 to -600 km elevation
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