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Evidence for thermal fatigue on Mars from rockfall patterns on impact crater slopes

Tesson, P.-A.; Conway, S. J.; Mangold, N.; Ciazela, J.; Lewis, S. R. and Mège, D. (2019). Evidence for thermal fatigue on Mars from rockfall patterns on impact crater slopes. In: 50th Lunar and Planetary Science Conference, 18-22 Mar 2019, The Woodlands, Houston, Texas, USA.

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Abstract

Individual block falls are one of the currently active surface processes on Mars. Similarly to Earth, clasts detach from upslope outcrops roll or bounce downslope, leaving a track on the substratum (Fig. 1). The trails show that the rockfalls are recent, as aeolian processes would infill topographic lows over time. Using rover-track erasure rates, these tracks are likely <100 ka.

On Earth, slope instability is usually caused by phase changes of H2O [1]. However, solar-induced thermal stress could also play a key-role in rock breakdown leading to rockfalls [2]. Although liquid water is not stable at the surface of Mars today, sub-surface water ice is known to be present from mid- to high-latitudes [3]. Water ice and CO2 seasonal frost on shadowed pole-facing slopes may exist at latitudes down to 30° [4] or less [5]. On the other hand, insolation-related thermal stress has been used to explain fracture orientation patterns in martian boulders observed by the Mars Exploration Rovers [6] and other studies suggest that it could cause rock breakdown on airless bodies [7]. Therefore, both phase transitions and solar-induced thermal stress are plausible mechanisms for rock breakdown and preconditioning slopes for rockfalls on modern Mars. In this study we analyze distribution of rockfalls on impact crater walls to assess whether one of these mechanisms could be involved in local rock breakdown.

Item Type: Conference or Workshop Item
Copyright Holders: 2019 The Authors
Project Funding Details:
Funded Project NameProject IDFunding Body
Characterizing the Martian water cycle by assimilating ExoMars 2016 Trace Gas Orbiter dataST/R001405/1UKSA UK Space Agency
Surface/atmosphere interactions from above and below.ST/S00145X/1UKSA UK Space Agency
Academic Unit/School: Faculty of Science, Technology, Engineering and Mathematics (STEM) > Physical Sciences
Faculty of Science, Technology, Engineering and Mathematics (STEM)
Research Group: Space
Item ID: 60254
Depositing User: Stephen Lewis
Date Deposited: 13 May 2019 08:47
Last Modified: 24 Jun 2019 13:52
URI: http://oro.open.ac.uk/id/eprint/60254
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