Comparison of the mineral composition of the sediment found in two Mars dunefields: Ogygis Undae and Gale crater – three distinct endmembers identified

Charles, H. R.; Titus, T. N.; Hayward, R. K.; Edwards, C. S.; Ahrens, Caitlin

doi:10.1016/j.epsl.2016.10.022

Cited by 9 publications

(11 citation statements)

References 35 publications

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“…This coupling between active sand and megaripple migration seems to be valid even locally, where only the megaripple portions that are directly in contact with the dune sand are moving (Figure 9 and Animations S10 and S11). In addition, our findings suggest that winds strong enough to saltate fine to medium sand-sized grains, abundant on Martian dunes (Charles et al, 2016;Weitz et al, 2018), would be sufficient to displace the coarse grains accumulating on the megaripple crests, given an abundance of saltating sand. However, the wind conditions necessary to move and maintain the megaripples are not constrained at the two study sites.…”

Section: 1029/2020je006446mentioning

confidence: 69%

Megaripple Migration on Mars

et al. 2020

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Aeolian megaripples, with 5‐ to 50‐m spacing, are abundant on the surface of Mars. These features were repeatedly targeted by high‐resolution orbital images, but they have never been observed to move. Thus, aeolian megaripples (especially the bright‐toned ones often referred as Transverse Aeolian Ridges—TARs) have been interpreted as relict features of a past climate. In this report, we show evidence for the migration of bright‐toned megaripples spaced 1 to 35 m (5 m on average) in two equatorial areas on Mars indicating that megaripples and small TARs can be active today. The moving megaripples display sand fluxes that are 2 orders of magnitudes lower than the surrounding dunes on average and, unlike similar bedforms on Earth, can migrate obliquely and longitudinally. In addition, the active megaripples in the two study areas of Syrtis Major and Mawrth Vallis show very similar flux distributions, echoing the similarities between dune crest fluxes in the two study areas and suggesting the existence of a relationship between dune and megaripple fluxes that can be explored elsewhere. Active megaripples, together with high‐sand flux dunes, represent a key indicator of strong winds at the surface of Mars. A past climate with a denser atmosphere is not necessary to explain their accumulation and migration.

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Section: 1029/2020je006446mentioning

confidence: 69%

Megaripple Migration on Mars

et al. 2020

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“…We know that small dust particles can remain suspended in the atmosphere of Mars in the present day, so it is likely that over time attrition will result in sedimentary particles becoming smaller, at which point they can be transported away from the crater in the daytime upslope winds. Larger abrading clasts may remain in the crater moat, as is evidenced in the Bagnold dune field in Gale crater (Charles et al, 2017;Hobbs et al, 2010). Behavior such as this might result in increased erosion of the moat, resulting in a positive feedback mechanism.…”

Section: Discussionmentioning

confidence: 97%

“…Alternatively, a coarse-grained lag deposit can armor underlying softer rocks. Accumulations of larger particles in crater moats are observed, for example, the Bagnold dune field in Gale crater (Charles et al, 2017;Hobbs et al, 2010).…”

Section: Erosion In Craters Filled With Sedimentary Depositsmentioning

confidence: 99%

Crater Mound Formation by Wind Erosion on Mars

2018

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Most of Mars' ancient sedimentary rocks by volume are in wind‐eroded sedimentary mounds within impact craters and canyons, but the connections between mound form and wind erosion are unclear. We perform mesoscale simulations of different crater and mound morphologies to understand the formation of sedimentary mounds. As crater depth increases, slope winds produce increased erosion near the base of the crater wall, forming mounds. Peak erosion rates occur when the crater depth is ∼2 km. Mound evolution depends on the size of the host crater. In smaller craters mounds preferentially erode at the top, becoming more squat, while in larger craters mounds become steeper sided. This agrees with observations where smaller craters tend to have proportionally shorter mounds and larger craters have mounds encircled by moats. If a large‐scale sedimentary layer blankets a crater, then as the layer recedes across the crater it will erode more toward the edges of the crater, resulting in a crescent‐shaped moat. When a 160 km diameter mound‐hosting crater is subject to a prevailing wind, the surface wind stress is stronger on the leeward side than on the windward side. This results in the center of the mound appearing to “march upwind” over time and forming a “bat‐wing” shape, as is observed for Mount Sharp in Gale crater.

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“…However, Charles et al (), using thermal emission spectra, have shown that there are differences in dune sand composition. The Bagnold Dunes in Gale Crater are olivine enriched, while dunes in Ogygis Undae are olivine deficient (Charles et al, ). The north polar dunes are basaltic with a hydrated mineral interpreted to be gypsum (Horgan et al, ; Langevin et al, ; Massé et al, ).…”

Section: Introductionmentioning

confidence: 99%

“…Spectral analysis of the dark dunes and sand sheets on Mars by Tirsch et al () indicates that they nearly all have the same mafic composition and that they are most likely to be derived from volcanic rocks. However, Charles et al (), using thermal emission spectra, have shown that there are differences in dune sand composition. The Bagnold Dunes in Gale Crater are olivine enriched, while dunes in Ogygis Undae are olivine deficient (Charles et al, ).…”

Section: Introductionmentioning

confidence: 99%

Dust Production by Abrasion of Eolian Basalt Sands: Analogue for Martian Dust

Bristow

Moller

2018

JGR Planets

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Dust is nearly ubiquitous on Mars, covering much of the planet's surface, having been redistributed by dust storms. Analysis of dust via landed instrumentation indicates a basaltic composition for its protolith; the same is interpreted for the dark dune sands encountered at rover field sites. In this paper, we used samples of eolian sands derived from basaltic volcanoes in an experiment to simulate dust production from basalt dune sands within an abrasion chamber. In addition, we used samples from gypsum dunes because gypsum is found within dune fields on the northern plains of Mars. The results, expressed as weight percent of sample reduced to dust, show a remarkably broad range over 4 orders of magnitude. Eolian abrasion of basalt sands can produce similar amounts of dust, as is the case for some desert sands on Earth. Some plausible Mars analogue materials can produce large amounts of dust, suggesting that eolian movement of basaltic sand and volcanic sediments on the surface of Mars is a potential source of fine‐grained sediment or dust.

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Comparison of the mineral composition of the sediment found in two Mars dunefields: Ogygis Undae and Gale crater – three distinct endmembers identified

Cited by 9 publications

References 35 publications

Megaripple Migration on Mars

Megaripple Migration on Mars

Crater Mound Formation by Wind Erosion on Mars

Dust Production by Abrasion of Eolian Basalt Sands: Analogue for Martian Dust

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