Rock coatings and aeolian abrasion on Mars: Application to the Pathfinder landing site

Kraft, Michaël; Greeley, R.

doi:10.1029/1999je001229

Cited by 22 publications

(16 citation statements)

References 49 publications

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“…They further noted that dust aggregate particles would be ineffective abrasive agents on the surface of Mars. The results of Kraft and Greeley [2000] support the formation of rock varnishes on Mars in accordance with our model of dust aggregates containing ferric oxides and sulfates in a poorly crystalline silicate matrix.…”

Section: Results: Comparison With Imp Spectra Of Martian Soils and Rockssupporting

confidence: 87%

A model for formation of dust, soil, and rock coatings on Mars: Physical and chemical processes on the Martian surface

et al. 2002

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[1] A model is presented here to explain the generation of surface material on Mars using chemical, magnetic, and spectroscopic data from Mars and geologic analogs from terrestrial sites. One basic premise is that the dust/soil units are not derived exclusively from local rocks, but are rather a product of global, and possibly remote, weathering processes. Another assumption in this model is that there are both physical and chemical interactions of the atmosphere with dust particles and that these two processes create distinctly different products. Physical processes distribute dust particles on rocks and drift units, forming physically aggregated layers; these are reversible processes. Chemical reactions of the dust/soil particles create alteration rinds on rock surfaces and cohesive, crusted surface units between rocks, both of which are relatively permanent materials. According to this model the dominant components of the dust/soil particles are derived from alteration of volcanic ash and tephra and contain primarily nanophase and poorly crystalline ferric oxide/oxyhydroxide phases as well as silicates. These phases are the alteration products that formed in a low-moisture environment. These dust/soil particles also contain a smaller amount of material that was exposed to more water and contains crystalline ferric oxides/oxyhydroxides, sulfates, and clay silicates. These components could have formed through hydrothermal alteration at steam vents or fumeroles, thermal fluids, or through evaporite deposits. Wet/dry cycling experiments are presented here on Mars soil analogue mixtures containing poorly crystalline and crystalline components dominated by nanophase to $2 mm diameter particles. Cemented products of these soil mixtures are formed in these experiments, and variation in the surface texture was observed for samples containing smectites, nonhydrated silicates, or sulfates. Reflectance spectra were measured of the initial particulate mixtures, the cemented products, and ground versions of the cemented material. The spectral contrast in the visible/near-infrared and midinfrared regions is significantly reduced for the cemented material compared to the initial soil and somewhat reduced for the ground, cemented soil compared to the initial soil. The results of this study suggest that transient fluvial activity on Mars will have a profound effect on the texture and spectral properties of the dust/soil particles on the surface. The model developed in this study provides an explanation for the generation of cemented or crusted soil units and rock coatings on Mars and may explain albedo variations on the surface observed near large rocks or crater rims.

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Section: Results: Comparison With Imp Spectra Of Martian Soils and Rockssupporting

confidence: 87%

A model for formation of dust, soil, and rock coatings on Mars: Physical and chemical processes on the Martian surface

et al. 2002

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“…In addition, the question of whether coatings and/or rinds survive on rocks that are surrounded by saltating sand grains must also be considered. Although amorphous silica coatings are less susceptible to abrasion than calcrete and rock varnish coatings [ Kraft and Greeley , 2000], desert silica “glazes” found on Earth are weak and removed easily in an eolian environment [ Dorn , 1998]. However, there have been reports of possible amorphous silica coatings on dune sands in western Egypt [ El‐Baz and Prestel , 1980].…”

Section: Discussionmentioning

confidence: 99%

Global spectral classification of Martian low‐albedo regions with Mars Global Surveyor Thermal Emission Spectrometer (MGS‐TES) data

2007

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Martian low‐albedo surfaces (defined here as surfaces with Mars Global Surveyor Thermal Emission Spectrometer (MGS‐TES) albedo values ≤0.15) were reexamined for regional variations in spectral response. Low‐albedo regions exhibit spatially coherent variations in spectral character, which in this work are grouped into 11 representative spectral shapes. The use of these spectral shapes in modeling global surface emissivity results in refined distributions of previously determined global spectral unit types (Surface Types 1 and 2). Pure Type 2 surfaces are less extensive than previously thought, and are mostly confined to the northern lowlands. Regional‐scale spectral variations are present within areas previously mapped as Surface Type 1 or as a mixture of the two surface types, suggesting variations in mineral abundance among basaltic units. For example, Syrtis Major, which was the Surface Type 1 type locality, is spectrally distinct from terrains that were also previously mapped as Type 1. A spectral difference also exists between southern and northern Acidalia Planitia, which may be due in part to a small amount of dust cover in southern Acidalia. Groups of these spectral shapes can be averaged to produce spectra that are similar to Surface Types 1 and 2, indicating that the originally derived surface types are representative of the average of all low‐albedo regions.

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“…Yardangs and TARs were mapped on a mosaic of images from the Mars Reconnaissance Orbiter Context Camera (CTX) with resolution of~6 m per pixel (see supporting information S1; Malin et al, 2007). The exact magnitude of this timescale depends on the size of the yardang, the erodibility of the material, and the strength of the wind, but from estimates of Martian aeolian abrasion rates (Bridges et al, 2004;Greeley et al, 1982;Kraft & Greeley, 2000), we assume a formative timescale of at least hundreds of thousands of years. Yardangs tend to form asymmetrically with slightly blunted upwind ends and tapered downwind ends.…”

Section: Methodsmentioning

confidence: 99%

Wind in Jezero Crater, Mars

Day

Dorn

2019

Geophysical Research Letters

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Wind generates erosional and depositional morphologies across Mars, including in Jezero crater, the planned landing site for the Mars 2020 rover. Known for subaqueously formed sedimentary features, Jezero crater also hosts wind‐formed features that provide insights about the local wind regime. We combine interpretations from dunes, wind streaks, transverse aeolian ridges, and yardangs to holistically understand the recent history of wind in Jezero crater. Together, these features describe modern easterly winds trending toward 263° ± 8° and older southwesterly winds that formed small yardangs. Previous research has suggested that aeolian processes eroded the delta deposit in Jezero crater. We propose early southwesterly winds removed the majority of material, exposing the more lithified units seen today. Modern easterly winds continue to cause erosion, but lithologic heterogeneities remain the dominant control on delta deposit evolution. Aeolian erosion has accentuated existing sedimentary structures, leaving the striking delta remnant seen today.

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Rock coatings and aeolian abrasion on Mars: Application to the Pathfinder landing site

Cited by 22 publications

References 49 publications

A model for formation of dust, soil, and rock coatings on Mars: Physical and chemical processes on the Martian surface

A model for formation of dust, soil, and rock coatings on Mars: Physical and chemical processes on the Martian surface

Global spectral classification of Martian low‐albedo regions with Mars Global Surveyor Thermal Emission Spectrometer (MGS‐TES) data

Wind in Jezero Crater, Mars

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