The Role of Seasonal Sediment Transport and Sintering in Shaping Titan’s Landscapes

Titan is a sedimentary world, with widespread lakes1, rivers2, fans3, eroded canyonlands4, dissected plateaux5, and sand dunes6. The bulk of sediments on Saturn’s moon are thought to be largely made of mechanically weak7 organic grains8-9, possibly prone to rapid abrasion into dust. Yet, Titan’s equatorial sand dunes are thought to be relatively old (10s–100s kyr)10 and active8,10-11. Sustaining Titan’s sand dunes over geologic timescales thus requires a mechanism that produces sand-sized organic particles at equatorial latitudes7. We explore the hypothesis that a combination of sintering, when sediment grains are at rest, and abrasion, when they are transported by methane rivers or nitrogen winds, could produce sand grains with a consistent, equilibrium size. We find that episodic sintering and abrasion may readily produce sand-sized sediments under Titan’s surface conditions, and supply Titan’s equatorial dunes with well-sorted organic sand at Earth-like transport frequencies. Predictions are consistent with geologic constraints on grain sizes in the dune fields12 as well as the frequency of methane rainstorms13 and sand-transporting winds14-15. Our findings support the hypothesis of a global sedimentary cycle on Titan, driven by seasonal climate forcing, and mediated by episodic sintering and abrasion of organic sand grains by rivers and winds.