Timing and spatial variability of post-Noachian fluvial erosion on Mars

Recent studies of valley networks and alluvial deposits have shown that Mars experienced one or more phases of Late Hesperian or Early Amazonian fluvial erosion. Fluvial erosion on post-Noachian Mars was spatially and temporally variable. Equatorial regions within ±30° latitude showed highly variable fluvial erosion of Hesperian and Hesperian-Amazonian craters, with large alluvial fans concentrated from 15–30°S and 40°W east to 40°E, little fluvial erosion around equatorial Arabia Terra, and moderate erosion elsewhere. Large Amazonian craters lack deep wall dissection. From about 30–45°N and S, glacial and fluvial erosion (likely by meltwater) modified craters, whereas ice flow involved less melting poleward of 45°N and S. The objective of this project is to investigate the spatial and temporal variability of post-Noachian fluvial erosion on Mars. We will place a late bound on the timing of equatorial fluvial erosion and quantify the variable erosion of post-Noachian craters. We are estimating crater ages using crater counts and quantifying the amount of fluvial erosion. This work will advance our understanding of the paleoclimate variability on Hesperian to Early Amazonian Mars, and it will help to focus future in-situ investigations and sampling of the relatively well preserved aqueous deposits from this last major phase of erosion. It also will constrain future atmospheric models by showing when, where, and how much erosion occurred.