Tsunami waves extensively resurfaced the shorelines of an early Martian ocean

Abstract

It has been proposed that ~3.4 billion years ago an ocean fed by enormous catastrophic floods covered most of the Martian northern lowlands. However, a persistent problem with this hypothesis is the lack of definitive paleoshoreline features. Here, based on geomorphic and thermal image mapping in the circum-Chryse and northwestern Arabia Terra regions of the northern plains, in combination with numerical analyses, we show evidence for two enormous tsunami events possibly triggered by bolide impacts, resulting in craters ~30 km in diameter and occurring perhaps a few million years apart. The tsunamis produced widespread littoral landforms, including run-up water-ice-rich and bouldery lobes, which extended tens to hundreds of kilometers over gently sloping plains and boundary cratered highlands, as well as backwash channels where wave retreat occurred on highland-boundary surfaces. The ice-rich lobes formed in association with the younger tsunami, showing that their emplacement took place following a transition into a colder global climatic regime that occurred after the older tsunami event. We conclude that, on early Mars, tsunamis played a major role in generating and resurfacing coastal terrains.

Geological Evidence of Planet‐Wide Groundwater System on Mars

“…There is a notable consistency between the stationary water level at approximately −4,000 m in the basins analyzed and previous works that suggests the presence of a northern Late Hesperian ocean shoreline between 3,940 and −4,100 m (Costard et al, ; Ivanov et al, J. A. Rodriguez et al, ; Webb, ). Ivanov et al () also date the Deuteronilus shoreline to 3.6 Ga, which is close to the model ages of several of the craters studied in this work (see Table S1 for crater age estimation).…”

“…A. P. Rodriguez, Zarroca et al, ; J. A. Rodriguez et al, ; Tanaka et al, ), followed by the retreat of surface water into subsurface aquifers underneath a thick ice‐rich permafrost zone (Clifford & Parker, ) where it became part of groundwater stores (Andrews‐Hanna et al, ). Groundwater could have been a major factor in the origin and evolution of water‐related sedimentary systems on Mars (Andrews‐Hanna et al, , ; Goldspiel & Squyres, ; Howard, ; Malin & Carr, ; Siebach et al, ; Stack et al, ).…”

Grid Mapping the Northern Plains of Mars: Using Morphotype and Distribution of Ice‐Related Landforms to Understand Multiple Ice‐Rich Deposits in Utopia Planitia

“…The lobes each have a ridge at the front (white arrow on Figure b). These lobes share similar morphologic characteristics with the runup lobate deposits that were recently interpreted as tsunami deposits (Costard et al, ; Rodriguez et al, ). All of these features superimpose the VBF and collectively suggest that there was a large (1,000‐km diameter) reservoir of water/mud in the deepest portions of the Utopia basin (Ivanov et al, ; Skinner & Mazzini, ).…”

Mars: a small terrestrial planet

“…Its deposits could be separated from the Noachian deposits by the emplacement of Hesperian effusive volcanic plains deduced from buried structures . The presence of water-rich sediments would agree with the occurrence of mudflows (Jöns 1984) and with channels occurring on bordering terrains and interpreted as the result of tsunami (Rodriguez et al 2016). The latter study implies a much longer duration of episodic outflow channel activity than previously thought.…”