Recent ice ages on Mars

Head, J. W.; Mustard, John F.; Kreslavsky, M. A.; Milliken, R. E.; Marchant, David R.

doi:10.1038/nature02114

Cited by 708 publications

(578 citation statements)

References 34 publications

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“…Only small shallow cracks observed within some polygon centers were likely to have been formed subsequently. It is not clear, however, how much ground ice existed during times of higher obliquity when these polygons were formed and ground ice was more stable in the upper surface layer than it is today (e.g., Hecht, 2002;Head et al, 2003). Currently, UP1 polygons are more influenced by degradation through sublimation.…”

Section: Genesis Of Mars Polygons and Environmental Implicationsmentioning

confidence: 98%

“…14). The large upland polygons (UP1) are probably very old and were formed after the deposition of the mantling material during conditions of high obliquity Head, 2000, 2002;Mustard et al, 2001;Head et al, 2003). An old age is also indicated by the fact that these polygons are truncated by the scalloped depressions (Fig.…”

Section: Genesis Of Mars Polygons and Environmental Implicationsmentioning

confidence: 99%

“…Geologically, the region is characterized by two main units: the Vastitas Borealis interior unit (ABv i ), which underlies the Astapus Colles unit (ABa) (Tanaka et al, 2005). The ABa unit is interpreted as a fine-grained volatile-rich (i.e., ice-rich) mantling layer tens of meters thick which was deposited during recent variations in Mars' orbital parameters (i.e., higher obliquity) (e.g., Head, 2000, 2002;Mustard et al, 2001;Head et al, 2003). The older ABv i unit consists mainly of outflow channel sediments and subsequently reworked ice-rich deposits (Tanaka et al, 2005).…”

Section: Mars (Utopia Planitia Up)mentioning

confidence: 99%

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Polygon pattern geomorphometry on Svalbard (Norway) and western Utopia Planitia (Mars) using high-resolution stereo remote-sensing data

et al. 2011

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Polygonal systems formed by thermal contraction cracking are complex landscape features widespread in terrestrial periglacial regions. The manner in which cracking occurs is controlled by various environmental factors and determines dimension, shape, and orientation of polygons. Analogous small-scale features are ubiquitous in Martian mid-and high-latitudes, and they are also inferred to originate from thermal contraction cracking. We studied the geomorphometry of polygonally-patterned ground on Svalbard to draw a terrestrial analogy to small-scale polygonal structures in scalloped terrain in Martian mid-latitudes. We performed a comparative quantitative terrain analysis based on high-resolution stereo remote-sensing data (HRSC-AX and HiRISE) in combination with terrestrial field data and multivariate statistics to determine the relationship of polygon geomorphometry to local environmental conditions. Results show that polygonal structures on Svalbard and in Utopia Planitia on Mars are similar with respect to their size and shape. A comparable thermal contraction cracking genesis is likely. Polygon evolution, however, is strongly related to regional and local landscape dynamics. Individual polygon dimensions and orthogonality vary according to age, thermal contraction cracking activity, and local subsurface conditions. Based on these findings, the effects of specific past and current environmental conditions on polygon formation on Mars must be considered. On both Earth and Mars, the smallest polygons represent young, recently-active low-centered polygons that formed in fine-grained ice-rich material. Small, low-centered Martian polygons show the closest analogy to terrestrial low-centered ice-wedge polygons. The formation of composite wedges could have occurred as a result of local geomorphological conditions during past Martian orbital configurations. Larger polygons reflect past climate conditions on both Earth and Mars. The present degradation of these polygons depends on relief and topographical situation. On Svalbard the thawing of ice wedges degrades high-centered polygons; in contrast, the present appearance of polygons in Utopia Planitia is primarily the result of contemporary dry degradation processes.

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Section: Genesis Of Mars Polygons and Environmental Implicationsmentioning

confidence: 98%

Section: Genesis Of Mars Polygons and Environmental Implicationsmentioning

confidence: 99%

Section: Mars (Utopia Planitia Up)mentioning

confidence: 99%

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Polygon pattern geomorphometry on Svalbard (Norway) and western Utopia Planitia (Mars) using high-resolution stereo remote-sensing data

et al. 2011

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“…Another hypothesis that is also related to the near-surface of the martian regolith is that sand-grade material might be buried by centimeteror meter-scale deposits of a dust -and ice-rich mantling material. This mantle, almost pervasive at N60°latitudes in both hemispheres but transitioning to a dissected, discontinuous mantle at 30-60°l atitude (Mustard et al, 2001;Kreslavsky and Head, 2002;Head et al, 2003) is partly responsible for topographic smoothing at subkilometer scale at latitudes N30°in both hemispheres (Kreslavsky and Head, 2000). It is interpreted to be composed of water ice condensed from the atmosphere that includes and is overlain by fine air fall dust.…”

Section: Sediment Source and Spatial Distributionmentioning

confidence: 99%

Transverse Aeolian Ridges (TARs) on Mars

et al. 2008

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Aeolian processes are probably the dominant ongoing surface process on Mars; Large Dark Dunes (LDDs), particularly common aeolian landforms, were first recognized in the early 1970s. Recent, higher resolution images have revealed another, morphologically distinct, large population of smaller, ripple-like aeolian bedforms that have been termed "Transverse Aeolian Ridges" (TARs) as it is unknown whether they formed as large ripples or small dunes. We have begun a new study of TARs that examines their distribution, orientation, and morphology using N 10,000 high-resolution Mars Orbiter Camera (1.5 to 8 m/pixel resolution) images in a 45°longitude wide, pole-to-pole survey. The aim of this study is to assess whether TARs are active, to identify possible sediment sources and pathways, and to determine the volumes of sediment that they comprise. We present results from the first half of this study, in which we examine the northern hemisphere, and describe a new three-part classification scheme used to aid the survey. Our results show that TARs are abundant but not ubiquitous: preferentially forming proximal to friable, layered terrains such as those found in Terra Meridiani -the location of the ongoing Mars Exploration Rover "Opportunity" mission. TAR distribution in the northern hemisphere shows a strong latitudinal dependence with very few TARs being found north of ∼ 30°N. We also find that in most cases TARs are less mobile than LDDs, a conclusion possibly explained by Mars Exploration Rover Opportunity observations that show TARlike ripples to have a core of fine material armored by a monolayer of granule-sized particles. This could disallow significant bedform movement under the current wind regime. That TARs are essentially inactive is confirmed by superposition relations with slope streaks and LDDs and by observations of superposed impact craters. We suggest that observations made by the Opportunity Rover in Terra Meridiani indicate that the small aeolian bedforms common here are ripples and not small dunes. Farther south, these bedforms transition into larger features indistinguishable from TARs, suggesting that TARs (in the Meridiani area at least) are ripples and not dunes.

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“…These mantling deposits are postulated to be made of ground ice-cemented dust with unknown relative proportions of dust and ice (e.g. Mustard et al, 2001;Kreslavsky and Head, 2002;Head et al, 2003). They may have formed by transport of ice from polar reservoirs, followed by airfall deposition in mid to high latitudes during periods of high obliquity less than 5 Ma ago; after a return to lower obliquity (including the present), the ice-rich mantle would progressively become eroded from lower to higher latitudes (e.g., Mustard et al, 2001;Head et al, 2003;, much as the Earth's annual orbital progression affects seasonal snow cover on Earth.…”

Section: Introductionmentioning

confidence: 99%