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Recent Basal Melting of a Midā€Latitude Glacier on Mars

Published version
Peer-reviewed

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Authors

Butcher, Frances EG  ORCID logo  https://orcid.org/0000-0002-5392-7286
Balme, MR 
Gallagher, C 
Arnold, NS 
Conway, SJ 

Abstract

jats:titleAbstract</jats:title>jats:pEvidence for past basal melting of young (late Amazonianā€aged), debrisā€covered glaciers in Mars' midā€latitudes is extremely rare. Thus, it is widely thought that these viscous flow features (VFFs) have been perennially frozen to their beds. We identify an instance of recent, localized wetā€based midā€latitude glaciation, evidenced by a candidate esker emerging from a VFF in a tectonic rift in Tempe Terra. Eskers are sedimentary ridges deposited in iceā€walled meltwater conduits and are indicative of glacial melting. We compare the candidate esker to terrestrial analogues, present a geomorphic map of landforms in the rift, and develop a landsystem model to explain their formation. We propose that the candidate esker formed during a transient phase of wetā€based glaciation. We then consider the similarity between the geologic setting of the new candidate esker and that of the only other candidate esker to be identified in association with an existing midā€latitude VFF; both are within tectonic graben/rifts proximal to volcanic provinces. Finally, we calculate potential basal temperatures for a range of VFF thicknesses, driving stresses, mean annual surface temperatures, and geothermal heat fluxes, which unlike previous studies, include the possible role of internal strain heating. Strain heating can form an important additional heat source, especially in flow convergence zones, or where ice is warmer due to elevated surface temperatures or geothermal heat flux. Elevated geothermal heat flux within rifts, perhaps combined with locallyā€elevated strain heating, may have permitted wetā€based glaciation during the late Amazonian, when cold climates precluded more extensive wetā€based glaciation on Mars.</jats:p>

Description

Keywords

37 Earth Sciences, 3709 Physical Geography and Environmental Geoscience, 3705 Geology

Journal Title

Journal of Geophysical Research: Planets

Conference Name

Journal ISSN

2169-9097
2169-9100

Volume Title

122

Publisher

American Geophysical Union (AGU)