Intracrater sediment trapping and transport in Arabia Terra

Abstract:

Sediment transport on the modern martian surface is primarily driven by aeolian processes. Further, discoveries of ancient aeolian sandstones on Mars show that aeolian transport has been prevalent throughout the planet’s history. Aeolian erosion remobilizes ancient sediment that adds to the planet’s sedimentary budget driving a martian sedimentary cycle. To understand the modern martian sedimentary cycle, we explore craters in Arabia Terra as both sources and sinks of sediment using wind streaks and dunes as evidence of modern aeolian transport in these systems. Dunes and wind streaks are prevalent on the martian surface indicating active transport. These dunes and wind streaks often interact with crater topography, providing a means to study craters as sediment depo-centers on Mars.

We identified 116 craters with diameters >10 km where terminal dune fields were observed within the crater’s interior. These craters were then categorized based on the presence or absence of downwind wind streaks, which indicate whether sediment is being transported out of the crater. Crater wall slopes were measured at the closest location downwind of each terminal dune field from a wind-parallel transect from the rim of the crater down to the dune field. From this 116 crater dataset, 39 craters displayed a low albedo wind streak while 61 craters have no wind streaks present. Craters displaying a low albedo wind streak have a lower average crater wall slope (9.4° ± 5.5°) compared to craters without an associated wind streak (17.0° ± 5.8°). The results here show that the slope of a crater wall plays a dominant role in sediment transport out of a crater basin. Further, we interpret the 10° - 18° slope overlap between these two crater populations to represent the transition from a crater on Mars acting as a net sediment sink to a net sediment source in the planetary sediment budget.