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Young (late Amazonian), near-surface, ground ice features near the equator, Athabasca Valles, Mars

Icarus

By:
, , ,
DOI: 10.1016/j.icarus.2005.04.012

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Abstract

A suite of four feature types in a ???20 km2 area near 10?? N, 204?? W in Athabasca Valles is interpreted to have resulted from near-surface ground ice. These features include mounds, conical forms with rimmed summit depressions, flatter irregularly-shaped forms with raised rims, and polygonal terrain. Based on morphology, size, and analogy to terrestrial ground ice forms, these Athabascan features are interpreted as pingos, collapsing pingos, pingo scars, and thermal contraction polygons, respectively. Thermal Infrared Mapping Spectrometer (THEMIS) data and geological features in the area are consistent with a sedimentary substrate underlying these features. These observations lead us to favor a ground ice interpretation, although we do not rule out volcanic and especially glaciofluvial hypotheses. The hypothesized ground ice that formed the mounds and rimmed features may have been emplaced via the deposition of saturated sediment during flooding; an alternative scenario invokes magmatically cycled groundwater. The ground ice implicit in the hypothesized thermal contraction polygons may have derived either from this flooding/ground water, or from atmospheric water vapor. The lack of obvious flood modification of the mounds and rimmed features indicates that they formed after the most recent flood inundated the area. Analogy with terrestrial pingos suggests that ground ice may be still extant within the positive relief mounds. As the water that flooded down Athabasca Valles emerged via a volcanotectonic fissure from a deep aquifer, any extant pingo ice may contain evidence of a deep subsurface biosphere. ?? 2005 Elsevier Inc. All rights reserved.

Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Young (late Amazonian), near-surface, ground ice features near the equator, Athabasca Valles, Mars
Series title:
Icarus
DOI:
10.1016/j.icarus.2005.04.012
Volume
178
Issue:
1
Year Published:
2005
Language:
English
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
First page:
56
Last page:
73
Number of Pages:
18