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Fresh shallow valleys in the Martian midlatitudes as features formed by meltwater flow beneath ice

Hobley, Daniel E. J., Howard, Alan D. and Moore, Jeffrey M. 2014. Fresh shallow valleys in the Martian midlatitudes as features formed by meltwater flow beneath ice. Journal of Geophysical Research: Planets 119 (1) , pp. 128-153. 10.1002/2013JE004396

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Abstract

Significant numbers of valleys have been identified in the Martian midlatitudes (30–60°N/S), spatially associated with extant or recent ice accumulations. Many of these valleys date to the Amazonian, but their formation during these cold, dry epochs is problematic. In this study, we look in detail at the form, distribution, and quantitative geomorphology of two suites of these valleys and their associated landforms in order to better constrain the processes of their formation. Since the valleys themselves are so young and thus well preserved, uniquely, we can constrain valley widths and courses and link these to the topography from the Mars Orbiter Laser Altimeter and High-Resolution Stereo Camera data. We show that the valleys are both qualitatively and quantitatively very similar, despite their being >5000 km apart in different hemispheres and around 7 km apart in elevation. Buffered crater counting indicates that the ages of these networks are statistically identical, probably forming during the Late Amazonian, ~100 Ma. In both localities, at least tens of valleys cross local drainage divides, apparently flowing uphill. We interpret these uphill reaches to be characteristic of flow occurring beneath a now absent, relatively thin (order 101–102 m), regionally extensive ice cover. Ridges and mounds occasionally found at the foot of these valley systems are analogous to eskers and aufeis-like refreezing features. On the basis of their interaction with these aufeis-like mounds, we suggest that this suite of landforms may have formed in a single, short episode (perhaps order of days), probably forced by global climate change.

Item Type: Article
Date Type: Publication
Status: Published
Schools: Earth and Ocean Sciences
Subjects: Q Science > QE Geology
Additional Information: Publisher PDF uploaded in accordance with policy at http://www.sherpa.ac.uk/romeo/issn/2169-9097/ [Accessed 12 December 2016]
Publisher: Wiley-Blackwell
ISSN: 2169-9097
Funders: NASA
Date of First Compliant Deposit: 25 October 2016
Date of Acceptance: 21 December 2013
Last Modified: 28 Feb 2019 16:04
URI: http://orca.cf.ac.uk/id/eprint/95593

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