Planetary researchers have mapped and characterized ancient sand dune fields in the canyons of Valles Marineris on Mars. Their discovery offers new insights on past climatic conditions on the Red Planet.
This oblique color view from the HiRISE instrument onboard NASA’s Mars Reconnaissance Orbiter shows a lithified field of sand dunes within Melas Chasma, Valles Marineris. The large degree of preserved morphology for many of these paleodunes reveals important information regarding the acting wind regime and climate prior to their cementation. Image credit: NASA / JPL / University of Arizona.
Wind-driven sand dunes are common on modern Mars, and the presence of certain sedimentary rock layers indicates that these landforms occurred there in the past.
Using data from several instruments onboard NASA’s Mars Reconnaissance Orbiter and Mars Odyssey spacecraft, planetary scientist Matthew Chojnacki and colleagues explored dune-like features within Melas Chasma in the Valles Marineris region.
“Mapping extensive sedimentary rock deposits in Valles Marineris show clear evidence for preserved lithification and burial of dune fields,” said Dr. Chojnacki, a researcher in the Planetary Science Institute and the Lunar and Planetary Laboratory at the University of Arizona.
“While modern sand dunes and other wind formed features are common on the surface of Mars and other terrestrial planets, typically most of the deposits are worn away by erosion.”
“We identified and mapped extensive dune fields in the canyons of Valles Marineris which show clear evidence for lithification and burial.”
“This level of preservation is rare for terrestrial sand dunes due to ongoing erosion and tectonics.”
“Based on the dune deposit’s relationships to other geologic units and modern erosion rates we estimate these to be roughly a billion years old,” he said.
“Because of the duneforms’ size and spatial arrangements, which are not that much different to modern equivalents, we suggest that the climate and atmospheric pressure to have been similar to that of contemporary Mars.”
Context maps of Melas Chasma paleodune fields: (a) regional distribution of paleodune (blue polygons outlined in white) and modern (red polygons) dune fields; (b) Southwest Melas Chasma reentrant canyon and the (d) central basin of Melas Chasma. Image credit: Murray Lab / Caltech / MSSS / NASA / JPL / Chojnacki et al., doi: 10.1029/2020JE006510.
Surface erosion and landscape evolution are greatly different on Earth and Mars.
“Water and tectonics that constantly reshape the surface of Earth are not currently a factor on Mars, thus there is an opportunity to learn from the geologic record of the red planet,” Dr. Chojnacki said.
“The ancient dune fields found within Valles Marineris, with their complex variety of landform shapes, degree of preservation, and context, reveal the richness of regional geology.”
“These results inform us that wind-driven sand transport, deposition, and lithification have occurred throughout much of Mars’ recent history and illustrate how landscape evolution there greatly differs compared to that of Earth.”
The study was published in the Journal of Geophysical Research: Planets.
Matthew Chojnacki et al. Ancient Martian Aeolian Sand Dune Deposits Recorded in the Stratigraphy of Valles Marineris and Implications for Past Climates. Journal of Geophysical Research: Planets, published online August 7, 2020; doi: 10.1029/2020JE006510