Valley formation on early Mars by subglacial and fluvial erosion

The southern highlands of Mars are dissected by hundreds of valley networks, which are evidence that water once sculpted the surface. Characterizing the mechanisms of valley incision may constrain early Mars climate and the search for ancient life. Previous interpretations of the geological record r...

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Bibliographic Details
Published in:Nature geoscience 2020-10, Vol.13 (10), p.663-668
Main Authors: Grau Galofre, Anna, Jellinek, A. Mark, Osinski, Gordon R.
Format: Article
Language:English
Subjects:
Climate
Climate prediction
Comparative analysis
Comparative studies
Earth analogs
Geomorphology
Glacial erosion
Glaciation
Glaciers
Groundwater
Highlands
Ice cover
Ice sheets
Mars
Mars climate
Mars surface
Morphometry
Networks
Runoff
Statistical analysis
Statistical methods
Subglacial erosion
Surface runoff
Surface water
Terrestrial environments
Valleys
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Summary:The southern highlands of Mars are dissected by hundreds of valley networks, which are evidence that water once sculpted the surface. Characterizing the mechanisms of valley incision may constrain early Mars climate and the search for ancient life. Previous interpretations of the geological record require precipitation and surface water runoff to form the valley networks, in contradiction with climate simulations that predict a cold, icy ancient Mars. Here we present a global comparative study of valley network morphometry, using a principal-component-based analysis with physical models of fluvial, groundwater sapping and glacial and subglacial erosion. We found that valley formation involved all these processes, but that subglacial and fluvial erosion are the predominant mechanisms. This is supported by predictions from models of steady-state erosion and geomorphological comparisons to terrestrial analogues. The inference of subglacial channels among the valley networks supports the presence of ice sheets that covered the southern highlands during the time of valley network emplacement.Some valleys in the southern highlands of Mars may have formed by subglacial erosion, consistent with a cold and icy early Mars, according to a statistical analysis of valley morphometry.
ISSN:1752-0894
1752-0908
DOI:10.1038/s41561-020-0618-x