Absolute dating and evolutionary model of large rock avalanches on Mars: Examples from the Hydraotes Chaos and Tiu Valles region

Landslides are geomorphological features observed on many planetary bodies, formed in a wide range of geological, geomorphological and environmental conditions. Hence, study of their morphological and morphometric characteristics, along with their absolute or relative dating, can improve the understanding of geological and environmental conditions at the time of their emplacement. On Mars, landslides are present over a very large part of the planet, and the most spectacular and best studied are those in Valles Marineris where many mass wasting phenomena occurred between Hesperian and Late Amazonian periods. The present study aims at improving the knowledge of Martian geological and geomorphological evolution including environmental conditions through absolute dating and morphological analysis of selected large landslides outside of Valles Marineris. These mass wasting features were used as proxies for revealing how active the relatively recent (Middle to Late Amazonian) geological environment of Mars was through the information of their trigger timings and degradation histories. The five landslides of our study, which have never been analyzed previously, are located in the region of Hydraotes Chaos and Tiu Valles near the dichotomy boundary. The geomorphological and morphometric analyses show that the studied landslides, classifiable as rock avalanches, exhibit morphological features and mobility similar to those of other terrestrial and Martian rock avalanches. The results obtained from the absolute dating reveal that these landslides occurred within a time range spanning from 835 Ma (±290) to 252 Ma (±100) ago, consistent with occurrences of other landslides in the equatorial region of Mars. The most plausible triggering factors include ground shaking resulting from meteoric impacts, marsquakes and volcanic events related to the evolution of Tharsis and Elysium regions during the Amazonian period. Local resurfacing events acting on the studied landslides are probably related to aeolian deflation and deposition, minor mass wasting events and impact cratering. Finally, the geomorphological characteristics of these landslide bodies and their absolute dating reveal a possible recent (< 250–150 Ma) tectonic activity along the flanks of Tiu Valles and the southern Hydraotes Channel. © 2023 Elsevier Inc.