According to a new paper by Planetary Science Institute Senior Scientist Catherine Weitz, a region on Mars may have been repeatedly habitable until relatively late in Martian history.
The Margaritifer Terra region, where deposits of clay-bearing sediments have been identified, contains some of the most extensively preserved landforms on Mars created by running water on its surface. “The presence of clays indicates a favourable environment for life because clays form and remain stable under neutral pH conditions where water persists for an extended period of time, minimising evaporation to form other minerals such as sulphates,” Weitz explained.
“We discovered that the Ladon basin region within Margaritifer Terra records a long history of flowing water beginning relatively early in Mars history around 3.8 billion years ago and continuing until up to 2.5 billion years ago, which is considered relatively recent,” said Weitz, lead author of the paper “Clay Sediments Derived from Fluvial Activity in and Around Ladon Basin, Mars,” which was published in the journal Icarus.
The study made use of data from NASA’s Mars Reconnaissance Orbiter’s High Resolution Imaging Science Experiment (HiRISE), Context Camera (CTX), and Compact Reconnaissance Imaging Spectrometers for Mars (CRISM).
“We identified clay-bearing sediments within the northern Ladon Valles, the southern Ladon basin, and the southwestern highlands surrounding the Ladon basin using orbital images,” Weitz said. “Furthermore, colourful light-toned layered sediments with relatively low bedding dips and clays spread over 200 kilometres are evidence that a lake was most likely present within the Ladon basin and northern Ladon Valles. The low-energy lake setting and the presence of clays support a life-friendly environment at the time.”
Clays formed in older highland terrains around Ladon basin, and water eroded through these clay-bearing highland materials to form the Ladon Valles channel, which then deposited sediments downstream into a lake within Ladon basin and northern Ladon Valles. The most recent and youngest water flow in the highlands is along the southwestern Ladon basin, where clays were deposited within blocked valleys and small topographic basins that are similar in age but smaller in scale to the Eberswalde delta deposit, which is located to the south of the study area.
“Our findings suggest that the clay sediments deposited by running water in Eberswalde were not unusual during this more recent period, as we see many examples of similar young valleys that deposited clays in the region,” Weitz said.
