Muddy rains produced by giant impacts into a primordial glaciated Mars may have played a crucial role in the emplacement of kilometers-thick mudstones on Mars, according to a new paper by a team led by Planetary Science Institute Senior Scientist Alexis Rodriguez.
These mudstones comprise the Solar System’s oldest known sedimentary rocks, according the paper “The Oldest Highlands of Mars May Be Massive Dust Fallout Deposits” (https://www.nature.com/articles/s41598-020-64676-z) published in Nature Scientific Reports.
PSI scientists Eldar Noe Dobrea, Jeffrey S. Kargel, David A. Crown, Kevin D. Webster, and Daniel C. Berman are co-authors on the paper.
Mars preserves the Solar System’s oldest water-modified landscapes. Rivers and glaciers are known to have extensively excavated the planet’s earliest highlands, which date back to about 4 billion years ago.
“We found that impact craters and adjoining fluvially emplaced sediments in these ancient highlands were wind-excavated to enormous depths, in some cases more than a kilometer. Wind on Mars can only move sediments that are sand- or silt-sized and finer, so very fine-grained sediments must largely make up these parts of the highlands,” Rodriguez said.
“When wind moves large amounts of sand, it produces dunes, but dunes are absent in these wind-sculpted terrains, suggesting that they are made mainly of silt, and perhaps clay,” co-author Berman said. “The wind erosion of these surfaces took place recently and might still be happening.”
