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Communication Dans Un Congrès Année : 2023

REVISITING ICE STREAMING IN KASEI VALLES: A FLUID DYNAMICS PERSPECTIVE

Résumé

Introduction: Outflow channels are among the largest, most arresting erosive landforms of Mars [1]. Up to two dozen systems of these large scoured megacanyons have been identified on Mars, spanning hundreds of kilometers in width, thousands of kilometers in length, and up to kilometers in depth. Activity in most outflow channels has been dated from the Hesperian period (~3.5-3 Byr ago) [1-3], with some channels displaying younger [2] and/or later [3] erosive episodes. Channel headwaters typically originate in collapsed chaotic terrains, are deepest at the head and decrease downflow, and rarely have tributaries [1]. Within the channels there are landforms indicative of the flow of massive amounts of fluid, including streamlined islands and longitudinal grooves and ridges, often seen diverging around obstacles. Owing to the similar landforms carved by the Missoula megafloods observed in the Channeled Scablands on Earth [1,4], these martian outflow channels are analogously interpreted to be the result of ancient massive outburst floods [1-3], with calculated releasing discharges even larger than the terrestrial Missoula megafloods sourced by the collapse of glacial lake Missoula at the end of the last ice age [1,4]. Support for this hypothesis includes the presence and morphology of streamlined islands, the sheer scales of outflow channels, the presence of regularly spaced longitudinal ridges, and the presence of hanging valleys and U-shaped valleys [1,4,5,7]. Debate ensues, however, regarding the near surface stability and availability of liquid water during the Hesperian period required to produce erosion at the scales of observed outflow channels. Alternative hypotheses that could explain outflow channel formation include ice streaming [5-6] or regional construction and local erosion by turbulent lava flows [8-9]. Kasei Valles: Among the martian outflow channels, Kasei Valles stands out for its scale [7]. It is located in the Mare Acidalium and Lunae Palus quadrangles, flowing from the south in Echus Chasma (NW Valles Marineris) northward and then eastward into NW Chryse Planitia in a system of canyons spanning more than 2500 km long, 300 km wide, and 2 km deep at its largest [2-3]. Whereas Kasei Valles is interpreted to be the result of the catastrophic release of a subsurface aquifer located in Echus Chasma, past discussions have raised the possibility of an ice stream, i.e., a fast-flowing megaglacier, playing a role in its formation [5-6]. An ice stream is the only erosive process on Earth known to cause megacanyons at a scale comparable to Kasei, with the currently active NE Greenland ice stream (Fig.
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hal-04204593 , version 1 (12-09-2023)

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  • HAL Id : hal-04204593 , version 1

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Anna Grau Galofre, Alexandra Huff, Axel Noblet. REVISITING ICE STREAMING IN KASEI VALLES: A FLUID DYNAMICS PERSPECTIVE. Lunar and Planetary Science Conference, LPI contributions, Mar 2023, Woodlands, United States. ⟨hal-04204593⟩
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