Evidence for different episodes of aeolian construction and a new type of wind streak in the 2016 ExoMars landing ellipse in Meridiani Planum, Mars

Silvestro, S.; Vaz, D. A.; Achille, G. Di; Popa, Iolanda Valentina; Esposito, F.

doi:10.1002/2014je004756

Cited by 22 publications

(12 citation statements)

References 67 publications

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“…The meter-scale bedforms on Herschel are morphologically different from Martian intracrater TARs, but present some overlap with the plain ripples mapped by Silvestro et al (2015a) in Meridiani Planum. Terrestrial aeolian megaripples also present similar H-index values for lower wavelengths, although the reduce number of measurements we show are probably not representative of the variance that those bedforms present in our planet.…”

Section: Bedform H-index Comparisonmentioning

confidence: 88%

Migrating meter-scale bedforms on Martian dark dunes: Are terrestrial aeolian ripples good analogues?

et al. 2017

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a b s t r a c tUsing automatic bedform mapping, principal component analysis and clustering we present a multiscale morphodynamic survey of dunes and meter-scale ripples on Herschel crater, Mars. The main purpose of this study is to assess if the morphology and temporal evolution of Martian meter-scale ripples is comparable to the morphodynamic characteristics of terrestrial aeolian impact ripples.We demonstrate that the spatial variations of the mapped dune patterns are correlated with substrate topography, which also influences the spatial distribution of the height and celerity of dunes' slipfaces. This topographic forcing is also patent on the spatial distribution of the ripples, thus proving that a multiscale coupling of active bedforms exists on Herschel under the present surface conditions.We found that Martian meter-scale ripples are morphologically distinct from terrestrial aeolian ripples, presenting a lower degree of straightness. Only $3% of the mapped ripples can be considered sinuous or straight bedforms. Moreover, we conclude that this two-dimensional sub-population is restricted to well define dune settings, where factors that promote the elongation of the meter-scale ripples were identified: gravity transport on higher slopes, bedform obliquity and flow convergence on the leeward side of dunes. We also report that the different sets of ripples that were mapped and segmented do not present a transverse migration. Therefore we conclude that terrestrial aeolian ripples are not good analogues for Martian meter-scale bedforms, either in terms of morphology or dynamic evolution.

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Section: Bedform H-index Comparisonmentioning

confidence: 88%

Migrating meter-scale bedforms on Martian dark dunes: Are terrestrial aeolian ripples good analogues?

et al. 2017

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“…Multiple studies have now revealed present-day movement of sand by the wind and migration of bedforms (dunes and ripples collectively) in some environments in the current Martian climate and~6-mbar atmosphere (e.g., Banks et al, 2015;Banks et al, 2017;Bourke et al, 2008;Bridges et al, 2010Bridges et al, , 2012Bridges et al, , 2013Chojnacki et al, 2011Chojnacki et al, , 2014Chojnacki et al, , 2015Chojnacki et al, , 2017Chojnacki et al, , 2018aChojnacki et al, , 2018bFenton, 2006;Silvestro et al, 2010Silvestro et al, , 2011Silvestro et al, , 2013Silvestro et al, , 2016Sullivan et al, 2008). Dune field and sand sheet formation, activity, and stabilization, on both Earth and Mars, are driven by factors such as sediment availability and wind transport capacity, potentially initiated by changes in climatic conditions (e.g., Ayoub et al, 2014;Fenton et al, 2015Fenton et al, , 2018Kocurek, 1998;Kocurek et al, 2007;Kocurek & Lancaster, 1999;Runyon, Bridges, Ayoub, et al, 2017;Silvestro et al, 2015).…”

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confidence: 99%

Patterns in Mobility and Modification of Middle‐ and High‐Latitude Southern Hemisphere Dunes on Mars

et al. 2018

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Change detection analyses of aeolian bedforms (dunes and ripples), using multitemporal images acquired by the Mars Reconnaissance Orbiter High Resolution Imaging Science Experiment (HiRISE), can reveal migration of bedforms on Mars. Here we investigated bedform mobility (evidence of wind‐driven migration or activity), from analysis of HiRISE temporal image pairs, and dune field modification (i.e., apparent presence/lack of changes or degradation due to nonaeolian processes) through use of a dune stability index or SI (1–6; higher numbers indicating increasing evidence of stability/modification). Combining mobility data and SI for 70 dune fields south of 40°S latitude, we observed a clear trend of decreasing bedform mobility with increasing SI and latitude. Both dunes and ripples were more commonly active at lower latitudes, although some high‐latitude ripples are migrating. Most dune fields with lower SIs (≤3) were found to be active while those with higher SIs were primarily found to be inactive. A shift in prevalence of active to apparently inactive bedforms and to dune fields with SI ≥ 2 occurs at ~60°S latitude, coincident with the edge of high concentrations of H2O‐equivalent hydrogen observed by the Mars Odyssey Neutron Spectrometer. This result is consistent with previous studies suggesting that stabilizing agents, such as ground ice, likely stabilize bedforms and limit sediment availability. Observations of active dune fields with morphologies indicative of stability (i.e., migrating ripples in SI = 3 dune fields) may have implications for episodic phases of reworking or dune building, and possibly geologically recent activation or stabilization corresponding to shifts in climate.

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“…The plains ripples are aligned nearly north‐south (N‐S), at 002.5° (Fenton et al, ; Sullivan et al, ). Exposed crossbedding (Arvidson et al, ; Sullivan et al, ) and the presence of westward‐pointing ripple streaks (Fenton et al, ; Silvestro et al, ) indicate that the plains ripples are transverse bedforms built by unimodal easterly (~092.5°) winds. The age of the ripples is not known, but they were in place prior to an impact event at ~200 ka (Golombek et al, ).…”

Section: Introductionmentioning

confidence: 99%

“…Meridiani Planum on Mars has been the site of Mars Exploration Rover Opportunity 's traverse (centered at ~354.5°E, 2.1°S) over tens of kilometers of coarse‐grained ripples called “plains ripples” (e.g., Arvidson et al, ; Squyres et al, ). The plains ripples (see Figure a) typically have a wavelength of 2–4 m, crest lengths ranging from a few to several tens of meters, and heights of ~0.1–1 m (Golombek et al, ; Silvestro et al, ; Zimbelman et al, ). Similar to coarse‐grained ripples on Earth (also known as megaripples), the Meridiani plains ripples are composed of grains with a bimodal size distribution, with a monolayer of 1–2 mm rounded fragments of hematite concretions armoring an interior dominated by grains <250 μm in diameter (Sullivan et al, ; Weitz et al, ).…”

Section: Introductionmentioning

confidence: 99%

Climate Forcing of Ripple Migration and Crest Alignment in the Last 400 kyr in Meridiani Planum, Mars

2018

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The plains ripples of Meridiani Planum are the first paleo‐aeolian bedforms on Mars to have had their last migration episode constrained in time (to ~50–200 ka). Here we test how variations in orbital configuration, air pressure, and atmospheric dust loading over the past 400 kyr affect bedform mobility and crest alignment. Using the National Aeronautics and Space Administration Ames Mars Global Climate Model, we ran a series of sensitivity tests under a number of different conditions, seeking changes in wind patterns relative to those modeled for present‐day conditions. Results indicate that enhanced sand drift potential in Meridiani Planum correlates with (1) high axial obliquity, (2) a longitude of perihelion (Lp) near southern summer solstice, and (3) a greater air pressure. The last pulse of westward plains ripple migration likely occurred during the most recent obliquity (relative) maximum, from 111 to 86 ka. At Lp coinciding with southern summer solstice, the Mars Global Climate Model produced a westward resultant drift direction, consistent with the observed north‐south plains ripple crest alignment. However, smaller superposed ripples, aligned NNE‐SSW, are consistent with a strengthened northern summer Hadley return flow, occurring when Lp coincided with northern summer solstice. The superposed NNE‐SSW ripples likely formed as the axial obliquity decreased during the last relative maximum and Lp swung toward northern summer, from 86 to 72 ka. The timeline of bedform activity supports the proposed sequence of CO2 sequestration in the south polar residual cap over the past 400 kyr.

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Evidence for different episodes of aeolian construction and a new type of wind streak in the 2016 ExoMars landing ellipse in Meridiani Planum, Mars

Cited by 22 publications

References 67 publications

Migrating meter-scale bedforms on Martian dark dunes: Are terrestrial aeolian ripples good analogues?

Migrating meter-scale bedforms on Martian dark dunes: Are terrestrial aeolian ripples good analogues?

Patterns in Mobility and Modification of Middle‐ and High‐Latitude Southern Hemisphere Dunes on Mars

Climate Forcing of Ripple Migration and Crest Alignment in the Last 400 kyr in Meridiani Planum, Mars

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