Spectral reflectance properties of minerals exposed to simulated Mars surface conditions

Cloutis, E. A.; Craig, M. A.; Kruzelecky, Roman V.; Jamroz, Wes; Scott, Alan; Hawthorne, Frank C.; Mertzman, Stanley A.

doi:10.1016/j.icarus.2007.10.028

Cited by 81 publications

(90 citation statements)

References 68 publications

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“…Features associated with OH, including the O-H stretching overtone and metal-OH combination bands were relatively unaffected. Fe-related absorption bands in the 0.4-1.2-lm region in most minerals are usually also unaffected by such exposure, but nontronite did exhibit changes in its Fe absorption bands (Cloutis et al, 2008).…”

Section: Space Weatheringmentioning

confidence: 95%

Spectral reflectance properties of carbonaceous chondrites: 1. CI chondrites

Cloutis¹,

Hiroi²,

Gaffey³

et al. 2011

Icarus

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174

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a b s t r a c tExisting reflectance spectra of CI chondrites (18 spectra of 3 CIs) have been augmented with new (18 spectra of 2 CIs) reflectance spectra to ascertain the spectral variability of this meteorite class and provide insights into their spectral properties as a function of grain size, composition, particle packing, and viewing geometry. Particle packing and viewing geometry effects have not previously been examined for CI chondrites. The current analysis is focused on the 0.3-2.5 lm interval, as this region is available for the largest number of CI spectra. Reflectance spectra of powdered CI1 chondrites are uniformly dark (<10% maximum reflectance) but otherwise exhibit a high degree of spectral variability. Overall spectral slopes range from red (increasing reflectance with increasing wavelength) to blue (decreasing reflectance with increasing wavelength). A number of the CI spectra exhibit weak (<5% deep) absorption bands that can be attributed to both phyllosilicates and magnetite. Very weak absorption bands attributable to other CI phases, such as carbonates, sulfates, and organic matter may be present in one or a few spectra, but their identification is not robust. We found that darker spectra are generally correlated with bluer spectral slopes: a behavior most consistent with an increasing abundance of fine-grained magnetite and/or insoluble organic material (IOM), as no other CI opaque phase appears able to produce concurrent darkening and bluing. Magnetite can also explain the presence of an absorption feature near 1 lm in some CI spectra. The most blue-sloped spectra are generally associated with the larger grain size samples. For incidence and emission angles <60°, increasing phase angle results in darker and redder spectra, particularly below $1 lm. At high incidence angles (60°), increasing emission angle results in brighter and redder spectra. More densely packed samples and underdense (fluffed) samples show lower overall reflectance than normally packed and flat-surface powdered samples. Some B-class asteroids exhibit selected spectral properties consistent with CI chondrites, although perfect spectral matches have not been found. Because many CI chondrite spectra exhibit absorption features that can be related to specific mineral phases, the search for CI parent bodies can fruitfully be conducted using such parameters.

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Section: Space Weatheringmentioning

confidence: 95%

Spectral reflectance properties of carbonaceous chondrites: 1. CI chondrites

Cloutis¹,

Hiroi²,

Gaffey³

et al. 2011

Icarus

Self Cite

174

162

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“…1A). The surface exposure to the Martian environment and grain size effect have been shown to be unable to account for this reduced spectral contrast (Cloutis et al 2007(Cloutis et al , 2008Cooper & Mustard 1999). Admixture of non-phyllosilicate anhydrous components is therefore required to account for it.…”

Section: Data Selection and Modeling Methodsmentioning

confidence: 99%

Abundance of minerals in the phyllosilicate-rich units on Mars

Poulet¹,

Mangold²,

Loizeau³

et al. 2008

A&A

125

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Context. Phyllosilicates were definitely identified on Mars by the OMEGA (Observatoire pour la Minéralogie, l'Eau, les Glaces et l'Activité) instrument onboard the Mars Express spacecraft. The identification, characterization, and mapping of deposits of these minerals hold clues to the potential past habitability. They also constitute a key element in planning for future landing sites. Aims. To infer the environmental conditions that existed at the time of the formation of these minerals, it is critical to determine if and how the composition of the deposits vary in space and time.Methods. We applied radiative transfer modeling to the OMEGA reflectance spectra to derive the modal mineralogy (mineral abundances) of some phyllosilicate-rich deposits. Results. In many outcrops, including the large areas in Nili Fossae, the surface mineralogy is dominated by primary non-altered minerals, with minor fractions of phyllosilicates. These assemblages could result from hydrothermal alteration. By contrast, deposits in the Mawrth Vallis region exhibit a large content of hydrated phyllosilicates, which suggests that the rocks may be mature sedimentary rocks or altered volcanics. Evidence of alteration resulting from metamorphism due to an impact is reported in the central peak of a crater.

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“…Their samples of ferrihydrite -a common Fe oxyhydroxide in CI chondrites (Buseck and Hua, 1993), montmorillonite, and palagonitic soil all show a decrease in the depth of the 1.9 lm (and 3.0 lm) region H 2 O absorption feature at lower pressures; spectral slopes showed more complex behavior but generally became bluer over the 1.8-2.5 lm interval. Cloutis et al (2007Cloutis et al ( , 2008) exposed a variety of minerals to Mars surface conditions ($660 Pa CO 2 ) followed by the addition of UV irradiation, and then a lower pressure (1 Pa) excursion. Their experiments included smectites (beidellite, nontronite, montmorillonite, saponite), serpentine group phyllosilicates (berthierine, cronstedtite, halloysite, serpentine), as well as some organic materials and goethite.…”

Section: Low Atmospheric Pressure Effects On Atcc Constituentsmentioning

confidence: 99%