The Kaguya Gamma‐Ray Spectrometer uniquely identified uranium gamma‐ray lines from the Moon with a superior energy resolution of ∼1%. A global lunar map of uranium distribution is derived for the first time. It was found that uranium abundances vary up to 2 ppm with an average of ∼0.3 ppm, while the average thorium abundance was ∼1.2 ppm. From these analyses, significant variation in U/Th ratio was found in the farside of the Moon that had not been reported by previous observations or in lunar materials. Our observations suggest that the lunar highland is not as uniform as has been long considered.

10.1029/2010gl043061

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Citations (77)

Igneous Rock Classification at Gale (Sols 13-800)

Lunar and Planetary Science Conference (2015)

A. Cousin V. Sautter N. Mangold C. Fabre O. Forni

Source

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Citations (5)

Petrological Traverse of the Olivine Cumulate Séítah Formation at Jezero Crater, Mars: A Perspective From SuperCam Onboard Perseverance

Journal of Geophysical Research Planets (2023)

Olivier Beyssac O. Forni A. Cousin Arya Udry Linda C. Kah

Abstract Séítah is the stratigraphically lowest formation visited by Perseverance in the Jezero crater floor. We present the data obtained by SuperCam: texture by imagery, chemistry by Laser‐Induced Breakdown Spectroscopy, and mineralogy by Supercam Visible and Infrared reflectance and Raman spectroscopy. The Séítah formation consists of igneous, weakly altered rocks dominated by millimeter‐sized grains of olivine with the presence of low‐Ca and high‐Ca pyroxenes, and other primary minerals (e.g., plagioclase, Cr‐Fe‐Ti oxides, phosphates). Along a ∼140 m long section in Séítah, SuperCam analyses showed evidence of geochemical and mineralogical variations, from the contact with the overlying Máaz formation, going deeper in the formation. Bulk rock and olivine Mg#, grain size, olivine content increase gradually further from the contact. Along the section, olivine Mg# is not in equilibrium with the bulk rock Mg#, indicating local olivine accumulation. These observations are consistent with Séítah being the deep ultramafic member of a cumulate series derived from the fractional crystallization and slow cooling of the parent magma at depth. Possible magmatic processes and exhumation mechanisms of Séítah are discussed. Séítah rocks show some affinity with some rocks at Gusev crater, and with some Martian meteorites suggesting that such rocks are not rare on the surface of Mars. Séítah is part of the Nili Fossae regional olivine‐carbonate unit observed from orbit. Future exploration of Perseverance on the rim and outside of the crater will help determine if the observations from the crater floor can be extrapolated to the whole unit or if this unit is composed of distinct sub‐units with various origins.

Melt inclusions

Shock metamorphism

10.1029/2022je007638

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Citations (25)

The Petrochemistry of Jake_M: A Martian Mugearite

Science (2013)

Edward M. Stolper M. B. Baker Megan Newcombe M. E. Schmidt A. H. Treiman

"Jake_M," the first rock analyzed by the Alpha Particle X-ray Spectrometer instrument on the Curiosity rover, differs substantially in chemical composition from other known martian igneous rocks: It is alkaline (>15% normative nepheline) and relatively fractionated. Jake_M is compositionally similar to terrestrial mugearites, a rock type typically found at ocean islands and continental rifts. By analogy with these comparable terrestrial rocks, Jake_M could have been produced by extensive fractional crystallization of a primary alkaline or transitional magma at elevated pressure, with or without elevated water contents. The discovery of Jake_M suggests that alkaline magmas may be more abundant on Mars than on Earth and that Curiosity could encounter even more fractionated alkaline rocks (for example, phonolites and trachytes).

Petrochemistry

Fractional crystallization (geology)

Nepheline

Peralkaline rock

10.1126/science.1239463

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Citations (162)

Mineralogy of a Mudstone at Yellowknife Bay, Gale Crater, Mars

Science (2013)

D. T. Vaniman D. L. Bish D. W. Ming T. F. Bristow R. V. Morris

Sedimentary rocks at Yellowknife Bay (Gale crater) on Mars include mudstone sampled by the Curiosity rover. The samples, John Klein and Cumberland, contain detrital basaltic minerals, calcium sulfates, iron oxide or hydroxides, iron sulfides, amorphous material, and trioctahedral smectites. The John Klein smectite has basal spacing of ~10 angstroms, indicating little interlayer hydration. The Cumberland smectite has basal spacing at both ~13.2 and ~10 angstroms. The larger spacing suggests a partially chloritized interlayer or interlayer magnesium or calcium facilitating H2O retention. Basaltic minerals in the mudstone are similar to those in nearby eolian deposits. However, the mudstone has far less Fe-forsterite, possibly lost with formation of smectite plus magnetite. Late Noachian/Early Hesperian or younger age indicates that clay mineral formation on Mars extended beyond Noachian time.

Noachian

Hesperian

Forsterite

10.1126/science.1243480

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Citations (605)

Compositions of coarse and fine particles in martian soils at gale: A window into the production of soils

Icarus (2014)

A. Cousin P. Y. Meslin R. C. Wiens W. Rapin N. Mangold

Felsic

Regolith

Martian soil