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Hesperian equatorial thermokarst lakes in Ares Vallis as evidence for transient warm conditions on Mars

Nicholas Warner, Sanjeev Gupta, Jung-Rack Kim, Shih-Yuan Lin and Jan-Peter Muller
Hesperian equatorial thermokarst lakes in Ares Vallis as evidence for transient warm conditions on Mars
Geology (Boulder) (January 2010) 38 (1): 71-74

Abstract

On Earth, permafrost thawing is linked to climate warming. Similarly, on Mars, permafrost degradation, described from mid-latitude and equatorial settings, is likely linked to global or regional climate change. Putative thermokarst depressions identified on Mars are widely considered to be the result of sublimation, evaporation, or thawing of an ice-rich substrate. The possibility that the depressions formed by melting of permafrost to create alas-like lakes has been recently proposed, but is controversial, owing to the lack of primary evidence for liquid filling the depressions. Here we use high-resolution Mars Reconnaissance Orbiter Context Camera images and derived topographic data to characterize possible thermokarst terrain in Ares Vallis. The terrain comprises subcircular to irregular, flat-floored rimless topographic depressions that occur at varying elevations. We report the discovery of narrow channels connecting thermokarst-like depressions that provide evidence for the previous presence of ponded liquid water. Crater counts on these surfaces indicate resurfacing that is likely related to flood deposition of water-saturated sediments in Ares Vallis during the Hesperian (ca. 3.6-3.0 Ga). We infer that thermokarst lakes formed after flooding by thawing of ice within the sediments during transient warm periods in the Hesperian, a time previously considered to be too cold to permit ice thaw.


ISSN: 0091-7613
EISSN: 1943-2682
Coden: GLGYBA
Serial Title: Geology (Boulder)
Serial Volume: 38
Serial Issue: 1
Title: Hesperian equatorial thermokarst lakes in Ares Vallis as evidence for transient warm conditions on Mars
Affiliation: Imperial College London, Department of Earth Science & Engineering, London, United Kingdom
Pages: 71-74
Published: 201001
Text Language: English
Publisher: Geological Society of America (GSA), Boulder, CO, United States
References: 32
Accession Number: 2010-019097
Categories: Extraterrestrial geology
Document Type: Serial
Bibliographic Level: Analytic
Annotation: With GSA Data Repository Item 2010012
Illustration Description: illus. incl. 1 table
Secondary Affiliation: University College London, GBR, United Kingdom
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute. Reference includes data from GeoScienceWorld, Alexandria, VA, United States. Reference includes data supplied by the Geological Society of America, Boulder, CO, United States
Update Code: 201012
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