22 Aug 2016

New geologic mapping in the Martian northern plains reveals vast sedimentary deposits that were likely emplaced by two mega-tsunamis, according to research led by PSI Senior Scientist J. Alexis Palmero Rodriguez. PSI Senior Research Associate Thomas Platz also worked on the project.
The proposed tsunami events likely took place a few millions of years apart, during which period the ocean receded to a lower shoreline and the climate became significantly colder. The tsunamis could have been triggered by bolide impacts, which every 2 millions years could have generated marine impact craters approximately 30 kilometers in diameter.

“For more than a quarter century failure to identify shoreline features consistently distributed along a constant elevation has been regarded as inconsistent with the hypothesis that a vast ocean existed on Mars approximately 3.4 billion years ago. Our discovery offers a simple solution to this problem; widespread tsunami deposits distributed within a wide range of elevations likely characterize the shorelines of early Martian oceans,” Rodriguez said.
“Mega-tsunamis also form on Earth, and their deposits, too, show tremendous variability in their topographic distribution and inundation distances. However, these are extremely rare and catastrophic events, and consequentially most of their deposits are mostly obscured –or removed – by younger resurfacing processes.”

Image:
(Fig. 1) Left: Color-coded digital elevation model of the study area showing the two proposed shoreline levels of an early Mars ocean that existed approximately 3.4 billion years ago. Right: Areas covered by the documented tsunami events extending from these shorelines
(Fig. 2) View of a boulder-rich surface (yellow bars are 10 meters) deposited by the older tsunami, and then eroded by channels produced as the tsunami water returned to the ocean elevation level.