Rodriguez and 10 co-authors, reported in 2022 that in 1976, NASA’s Viking 1 Lander (V1L) was the frst spacecraft to operate successfully on the Martian surface. The V1L landed near the terminus of an enormous catastrophic food channel, Maja Valles. However, instead of the expected megafood record, its cameras imaged a boulder-strewn surface of elusive origin.
The authors identifed a 110-km-diameter impact crater (Pohl) ~ 900 km northeast of the landing site, stratigraphically positioned:
a) above catastrophic food-eroded surfaces formed~ 3.4Ga during a period of northern plains oceanic inundation, and
b) below the younger of two previously hypothesized megatsunami deposits.
These stratigraphic relationships suggest that a marine impact likely formed the crater. The authors' simulated impact-generated megatsunami run-ups closely match the mapped older megatsunami deposit’s margins and predict fronts reaching the V1L site. The site’s location along a highland-facing lobe aligned to erosional grooves supports a megatsunami origin.
The authors' mapping also shows that Pohl’s knobby rim regionally represents a broader history of megatsunami modifcation involving circum-oceanic glaciation and sedimentary extrusions extending beyond the recorded megatsunami emplacement in Chryse Planitia. Our fndings allow that rocks and soil salts at the landing site are of marine origin, inviting the scientifc reconsideration of information gathered from the frst in-situ measurements on Mars.
The authors concluded that Te circum-Chryse outfow channels are considered to be the primary source of Mars’ Late Hesperian northern ocean. Tese outfow channels converged into the Chryse Planitia northern lowland region10, where they comprise the most extensive contiguous catastrophic fooding landscape on the planet (Fig. 2a).
The authors' paleophysiographic reconstructions indicate that the Chryse Planitia outfow channel foors occur beneath the previously hypothesized higher paleoshoreline stand at − 3800 m (Fig. 2a). Terefore, these terrains comprise the only catastrophic food geologic record on Mars that was likely submerged beneath the Late Hesperian northern ocean. Furthermore, the younger megatsunami deposit covers most of these outfow channel sections; hence, the area provides a unique stratigraphic framework consisting of marine sedimentation over ocean-generating food features.
The authors identifed an impact crater, Pohl, which superposed the outfow channel foors and underlies the younger megatsunami deposit (Fig. 2), characterizing it as a highly probable marine crater. Their numerical simulations indicated that Pohl produced a megatsunami that extensively inundated the Chryse Planitia HLB plains. The modeled megatsunami upper closely matched the older megatsunami margins as mapped by Rodriguez, et al., supporting the simulation’s accuracy (Fig. 5). These simulations predict that the megatsunami reached the Viking 1 Lander site, thereby explaining the presence of regional run-up overfow indicators in the sedimentation features. These include:
1) a highland-facing lobe on which the lander sits, and
2) scour marks on an adjoining wrinkle ridge that extend over an elongated deposit forming part of the V1LD upper reaches.
In addition, the run-up erosional patterns also include scour marks clearly recognizable in high-resolution (decameter-scale) views (Fig. 7). The simulations also suggest that the megatsunami backwash could have produced the boulder imbrication observed at the Mars Pathfnder lander site (Fig. 5).
The authors' paleophysiographic reconstructions suggest that the Chicxulub impact is an Earth analog to Pohl. It also:
1) occurred within a shallow marine environment (~200 m),
2) had a transient cavity diameter of ~100 km, similar to Pohl, and
3) produced a similar megatsunami (~200 m onshore height, inland surges of ~300 km with elevation gains of ~150 m).
The authors' mapping results also carry important paleoenvironmental implications connected to the modifcation history of the megatsunami record in Chryse Planitia. For example, They found that Pohl’s knobby rim is part of a vast field of knobs and mesas scattered throughout the − 3800 m to − 4100 m regression areas of Chryse Planitia (Fig. 3). Some knobs superpose outfow channel streamlined islands (Fig. 3), and many occupy terrains outside the outfow channels, indicating that the field’s formation postdated outfow channel activity. At some locations, the field includes apparently glaciated terrains (Fig. 3), suggesting that a previously proposed circum-oceanic glacial erosion contributed to the field’s origin. Furthermore, the presence of possible tunnel channels and eskers superposed on the younger megatsunami deposit (e.g., Fig. S3d) would indicate that the glaciation phase persisted after the ocean’s coastal regression.
Another form of megatsunami resurfacing concerns the high abundance of previously proposed mud volcanoes over the younger megatsunami deposit (e.g., Fig. S3e) (proposed to mostly consist of waves that froze during run-up). The authors considered this a causative association in which the gradual release of entrapped seawater could have facilitated the eruptions (Fig. 8f).
Managed & Built by I2M Consulting, LLC | © 2010-
