Understanding the Chemistry of the Rocks at Jezero crater, Mars, through
the Combined Use of SuperCam Spectroscopic and Optical Techniques
Lucia Mandon
LESIA, Observatoire de Paris, Université PSL, CNRS, Sorbonne Université, Université de Paris, LESIA, Observatoire de Paris, Université PSL, CNRS, Sorbonne Université, Université de Paris, LESIA, Observatoire de Paris, Université PSL, CNRS, Sorbonne Université, Université de Paris
Author ProfileThierry Fouchet
LESIA, Observatoire de Paris, Université PSL, CNRS, Sorbonne Université, Université de Paris, LESIA, Observatoire de Paris, Université PSL, CNRS, Sorbonne Université, Université de Paris, LESIA, Observatoire de Paris, Université PSL, CNRS, Sorbonne Université, Université de Paris
Author ProfileClément Royer
LESIA, Observatoire de Paris, Université PSL, CNRS, Sorbonne Université, Université de Paris, LESIA, Observatoire de Paris, Université PSL, CNRS, Sorbonne Université, Université de Paris, LESIA, Observatoire de Paris, Université PSL, CNRS, Sorbonne Université, Université de Paris
Author ProfileAbstract
The SuperCam instrument onboard Perseverance rover has remote imaging
(RMI), VISIR, LIBS, Raman and Time-Resolved Luminescence (TRL)
capabilities. RMI images of the rocks at the Octavia Butler landing site
have revealed important granular texture diversities. VISIR raster point
observations have revealed important differences in the 2.10-2.50 µm
infrared range (metal-hydroxides); many include water features at
1.40±0.04 and 1.92±0.02 µm [1]. LIBS observations on the same points
analyzed by VISIR revealed important differences in the concentrations
of major elements, suggesting mineral grain sizes larger than the laser
beam (300-500 µm). LIBS and VISIR show coherent results in some rock
surfaces that are consistent with an oxy-hydroxide (e.g., ferrihydrite)
[1]. LIBS elemental compositions are consistent with pyroxenes,
feldspars, and more often feldspar-like glass, often enriched in silica.
Olivine compositions [1, 2] have been observed so far in LIBS data
(up to Sol 140) exclusively in rounded regolith pebbles. They have not
yet been observed in the rocks themselves, which are MgO-poor compared
to regolith and are consistent with FeO bearing pyroxenes (e.g.,
hedenbergite, ferrosilite). A 3x3 LIBS and VISIR raster (9x9 mm)
acquired on a low-standing rock on sol 90 exemplifies these finding. A
dark L-shaped filled void sampled by points 1 and 2 with possible
ferrihydrite (H seen in LIBS and VISIR spectra). Point 5 contains
abundant silica and alkali elements but is Al-depleted relative to
feldspars, consistent with dacitic glass composition. Point 7 has
TiO2 content consistent with ilmenite. Comparisons to
(igneous) Martian meteorites are potentially useful, e.g. [3], to
explain the presence of several minerals, although most Martian
meteorites are olivine-rich, e.g., more mafic than the rocks at the
landing site. In summary, the bedrock at Octavia Butler landing site can
be interpreted as showing evidence for relatively coarse-grained
weathered pyroxenes, iron and titanium oxides and feldspars, while the
local soil contains pebbles from a different source (richer in MgO)
incorporating olivine grains. References: [1] Mandon et al. 2021
Fall AGU, New Orleans, LA, 13-17 Dec. ; [2] Beyssac et al. 2021 Fall
AGU, New Orleans, LA, 13-17 Dec. ; [3] Garcia-Florentino et
al.(2021), Talanta, 224, 121863.