An equatorial periglacial landscape on Mars

Balme, M. R.; Gallagher, Colman

doi:10.1016/j.epsl.2009.05.031

Cited by 75 publications

(32 citation statements)

References 44 publications

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“…The southernmost extent of the icy impact craters in the northern hemisphere is greater than that indicated from the neutron spectrometer analysis and thus requires a long-term average atmospheric water content that is moderately higher (*25 pr microns) than the present value , geographically and temporally varying atmospheric water vapor content due to obliquity variations (Chamberlain and Boynton, 2007), geographic concentration of water vapor near the surface (Zent et al, 2010), or control of vapor pressure due to brines formed by deliquescent salts in the regolith . In addition, inference of possible (or previous) near-surface ice in near-equatorial regions has been made based on interpretation of certain landforms (e.g., Balme and Gallagher, 2009), but the lack of bright deposits with the behavior of ice exposed in fresh craters at low latitudes suggests that ice is no longer present at these locations within the depths excavated by the craters.…”

Section: Use Of Fresh Impacts To Infer Ground Icementioning

confidence: 99%

A New Analysis of Mars “Special Regions”: Findings of the Second MEPAG Special Regions Science Analysis Group (SR-SAG2)

et al. 2014

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A committee of the Mars Exploration Program Analysis Group (MEPAG) has reviewed and updated the description of Special Regions on Mars as places where terrestrial organisms might replicate (per the COSPAR Planetary Protection Policy). This review and update was conducted by an international team (SR-SAG2) drawn from both the biological science and Mars exploration communities, focused on understanding when and where Special Regions could occur. The study applied recently available data about martian environments and about terrestrial organisms, building on a previous analysis of Mars Special Regions (2006) undertaken by a similar team. Since then, a new body of highly relevant information has been generated from the Mars Reconnaissance Orbiter (launched in 2005) and Phoenix (2007) and data from Mars Express and the twin Mars Exploration Rovers (all 2003). Results have also been gleaned from the Mars Science Laboratory (launched in 2011). In addition to Mars data, there is a considerable body of new data regarding the known environmental limits to life on Earth-including the potential for terrestrial microbial life to survive and replicate under martian environmental conditions. The SR-SAG2 analysis has included an examination of new Mars models relevant to natural environmental variation in water activity and temperature; a review and reconsideration of the current parameters used to define Special Regions; and updated maps and descriptions of the martian environments recommended for treatment as "Uncertain" or "Special" as natural features or those potentially formed by the influence of future landed spacecraft. Significant changes in our knowledge of the capabilities of terrestrial organisms and the existence of possibly habitable martian environments have led to a new appreciation of where Mars Special Regions may be identified and protected. The SR-SAG also considered the impact of Special Regions on potential future human missions to Mars, both as locations of potential resources and as places that should not be inadvertently contaminated by human activity.

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Section: Use Of Fresh Impacts To Infer Ground Icementioning

confidence: 99%

A New Analysis of Mars “Special Regions”: Findings of the Second MEPAG Special Regions Science Analysis Group (SR-SAG2)

et al. 2014

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“…The polygonal fractures observed in Barth crater could have formed by desiccation as the lake dried, as has been proposed for similarly fractured terrains in other interpreted crater lakes (El Maarry et al, ; El Maarry et al, ). The polygons are large with respect to the interpreted unit thickness (Goehring, ), and alternative formation mechanisms include periglacial processes (Balme & Gallagher, ; Burr et al, ), thermal fracturing, or other diagenetic processes (Levy et al, ; Mellon, ). The presence of more small impact craters in a unit that is stratigraphically younger than the cratered plains, the scarped contact between these units, and the polygonal fractures, all suggest that this unit is more strongly indurated than the plains material.…”

Section: Unit Descriptions and Interpretationsmentioning

confidence: 99%

Ancient Stratigraphy Preserving a Wet‐to‐Dry, Fluvio‐Lacustrine to Aeolian Transition Near Barth Crater, Arabia Terra, Mars

2019

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Ancient lacustrine and aeolian sediments have been separately identified in a variety of locations on Mars. In this work, we interpret the depositional history of Barth crater and its surrounding area in Arabia Terra where exposed geologic units preserve a record of lacustrine and aeolian interaction. Aeolian sandstone in the study area overlies lacustrine strata and is interbedded with easily eroded interdune deposits. The aeolian sandstone preserves dune strata with structures that indicate paleo‐sediment transport toward the northwest. The aeolian unit also preserves a transition up‐section from separated barchan dunes to continuous transverse dunes, capturing the development of the ancient dune field from sediment limited to sediment rich. Inverted fluvial channels provide evidence that water was delivered to the area at the same time the dune field was present, providing a simple mechanism, via wetting and cementation, for aeolian strata preservation. This example of wet‐system aeolian accumulation preserves an upward drying sequence in the sedimentary record that may have been coincident with the widely hypothesized global climate transition. The terrains described in this work provide a framework for interpreting similar aeolian units in elsewhere on Mars, even where cross‐strata cannot be easily resolved.

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“…At the system's termination, Athabasca Valles debouches into the Elysium Basin, where previous work has identified Late Amazonian‐age (3–7 Ma) platy‐ridged terrain [ Murray et al , 2005]. This terrain morphology may be representative of a frozen paleolake that resulted from freezing of catastrophic floodwaters [ Scott and Chapman , 1991; Brackenridge , 1993; Murray et al , 2005; Balme and Gallagher , 2009; Balme et al , 2010] or flood lavas that were emplaced after the fluvial activity [ Plescia , 1990; McEwen et al , 1999; Hartmann and Berman , 2000; Keszthelyi et al , 2000; Plescia , 2003; Keszthelyi et al , 2004a; Keszthelyi et al , 2004b; Jaeger et al , 2007; Vaucher et al , 2009a]. A similar platy‐ridged morphology has been identified on the channel floors of Athabasca Valles [ Jaeger et al , 2007] indicating that primary channel‐floor textures may be superimposed by these younger materials.…”

Section: Case Study: Athabasca Vallesmentioning

confidence: 99%

Hydraulic modeling of a distributary channel of Athabasca Valles, Mars, using a high‐resolution digital terrain model

et al. 2012

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Estimating magnitudes of flow rates in outflow channels has a central role in developing understanding of the paleohydrology of Mars. The typical approach to flow estimation is to identify geomorphic features, which indicate bankfull levels, and then use a hydraulic model to convert these levels into flow rates. Data constraints have meant that important assumptions about model equations, boundary conditions and parameter values have been necessary. In this paper, we use a high‐resolution digital terrain model derived from NASA's Mars Reconnaissance Orbiter Context Camera stereopair imagery to develop a finer resolution step backwater hydraulic model than previously attempted. Furthermore, the data facilitate a more critical, more formal and broader assessment of this type of model than has previously been attempted. A distributary channel of Athabasca Valles is used as a case study. The median bankfull flow estimate was 39,000 m3 s−1, although estimates range up to 140,000 m3 s−1 depending on the assumptions employed. The principal uncertainties stem from assumptions about bankfull levels and downstream boundary conditions; and assumptions about the friction coefficient, criticality of flow, expansion and contraction losses, and geometric details of the channel are also important under certain conditions. Examination of additional DTMs further downstream would permit the analysis to be extended to hydraulic control sections that provide better‐known boundary conditions, hence improving flow estimates. It is concluded that new‐generation DTM data provide opportunity for deeper insight into the challenges and opportunities for modeling the paleohydrology of Mars, although further work is needed to achieve satisfactory levels of confidence.

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An equatorial periglacial landscape on Mars

Cited by 75 publications

References 44 publications

A New Analysis of Mars “Special Regions”: Findings of the Second MEPAG Special Regions Science Analysis Group (SR-SAG2)

A New Analysis of Mars “Special Regions”: Findings of the Second MEPAG Special Regions Science Analysis Group (SR-SAG2)

Ancient Stratigraphy Preserving a Wet‐to‐Dry, Fluvio‐Lacustrine to Aeolian Transition Near Barth Crater, Arabia Terra, Mars

Hydraulic modeling of a distributary channel of Athabasca Valles, Mars, using a high‐resolution digital terrain model

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