Comparative study of molards on the Mount Meager debris avalanche, Canada, and on Hale crater ejecta, Mars

• Main Authors: Morino, Costanza, Roberti, Gioachino, Conway, Susan J.
• Other Authors: School of Environment, Earth and Ecosystem Sciences Milton Keynes, Faculty of Science, Technology, Engineering and Mathematics Milton Keynes, The Open University Milton Keynes (OU)-The Open University Milton Keynes (OU), Laboratoire Magmas et Volcans (LMV), Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Jean Monnet - Saint-Étienne (UJM)-Université Clermont Auvergne 2017-2020 (UCA 2017-2020 )-Centre National de la Recherche Scientifique (CNRS)-Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), Institut national des sciences de l'Univers (INSU - CNRS)-Université Clermont Auvergne 2017-2020 (UCA 2017-2020 )-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Clermont Auvergne 2017-2020 (UCA 2017-2020 )-Centre National de la Recherche Scientifique (CNRS), Laboratoire de Planétologie et Géodynamique UMR 6112 (LPG), Université d'Angers (UA)-Université de Nantes - UFR des Sciences et des Techniques (UN UFR ST), Université de Nantes (UN)-Université de Nantes (UN)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)
• Format: Conference Object
• Language: English
• Published: HAL CCSD 2019
• Subjects: [SDU.STU.PL]Sciences of the Universe [physics]/Earth Sciences/Planetology; [SDU.STU.GM]Sciences of the Universe [physics]/Earth Sciences/Geomorphology; British Columbia; Canada; Hale; Ice; permafrost
• Online Access: https://hal.science/hal-02407787

International audience Molards are cones of debris that result from the disaggregation of ice-cemented blocks transported by mass movements (e.g., Cruden, Can. J. Earth Sci 1982; Milana, PPP 2016). Recently, the origin of molards has been directly linked to permafrost degradation (Milana, PPP 2016; Morino et al., EPSL 2018). On Earth, permafrost degradation has accelerated in periglacial environments (e.g., Brown and Romanovsky, PPP 2008), but few landforms exist to track this process over time, and molards are a rare example that can serve this purpose. A process similar to permafrost degradation is thought to occur also on Mars, where water ice is known to exist as ground ice polewards of 30-40° in both hemispheres (Byrne et al., Science 2009; Feldman et al., JGR 2004), and where volatiles (H2O, CO2, etc.) can easily change phase (Fanale and Cannon, JGR 1974). Volatile loss should play an important role in landscape evolution of Mars, so finding distinctive landforms that testify this under-debate process can aid in understanding the processes that shape the surface of the planet. Here, we present a comparative study of molards that we have found in the Mount Meager debris-avalanche deposits on Earth with conical landforms that we have identified in the flows emanating from the ejecta deposits of the one billion year old Hale crater on Mars. The Mount Meager debris avalanche (British Columbia, Canada) is the largest landslide in the Canadian history, and permafrost degradation is thought to have contributed to the release of the failure (Roberti et al., Geosphere 2017) and in the development of the molards. We compare morphometric and planimetric measurements of molards on Earth with those for the molard-like features identified in the ejecta of the Hale Crater on Mars, whose ice-rich nature has already been proposed based on other landforms (Jones et al., Icarus 2011). The visual similarity of the molards of the Mount Meager debris avalanche and of the ejecta flow of Hale crater suggest that they are both ...