A reassessment of impact crater degradation by climatic processes on early Mars

Crater degradation on Mars is a key to understand erosion through time. Strongly eroded craters in the highlands are interpreted to be the result of enhanced erosion rate during the Noachian epoch. While fluvial valleys climatic meaning and duration are still difficult to define (strongly warmer climate or episodic activity under slightly warmer climate), the enhanced Noachian craters degradation favors a prolonged erosion with high erosion rates. Most data used for classification and understanding of these craters were done using Viking data by photoclinometry. We choose here to use MOLA data in two Noachian regions to study the evolution of this degradation in time: North Hellas and Southern Margaritifer Terra

Stratigraphy and Geologic History of the InSight Landing Site, Mars

We describe the local stratigraphy and geologic history of a regolith-covered lava plain at the InSight landing site using orbital and lander observations

Sustained fluvial deposition recorded in Mars’ Noachian stratigraphic record

Orbital observation has revealed a rich record of fluvial landforms on Mars, with much of this record dating 3.6–3.0 Ga. Despite widespread geomorphic evidence, few analyses of Mars’ alluvial sedimentary-stratigraphic record exist, with detailed studies of alluvium largely limited to smaller sand-bodies amenable to study in-situ by rovers. These typically metre-scale outcrop dimensions have prevented interpretation of larger scale channel-morphology and long-term basin evolution, vital for understanding the past Martian climate. Here we give an interpretation of a large sedimentary succession at Izola mensa within the NW Hellas Basin rim. The succession comprises channel and barform packages which together demonstrate that river deposition was already well established >3.7 Ga. The deposits mirror terrestrial analogues subject to low-peak discharge variation, implying that river deposition at Izola was subject to sustained, potentially perennial, fluvial flow. Such conditions would require an environment capable of maintaining large volumes of water for extensive time-periods, necessitating a precipitation-driven hydrological cycle