Particulate gravity currents on Venus

Abstract

Canali are moderately sinuous channels, typically a few kilometers wide and hundreds of kilometers long, that occur principally on the plains of Venus. Plausible hypotheses for their formation include the following: open channels cut by exotic, low‐viscosity lavas; roofed‐over basaltic lava channels; or water on a cooler, wetter ancient Venus. Although it is accepted that a fluid cut these channels, none of these hypotheses are entirely satisfactory. It is therefore prudent to investigate other explanations. A particulate gravity current is a rapidly moving, sediment‐laden flow that moves downslope as a result of its high density compared to the ambient fluid. This high density is produced by suspension of dense particles in a lower‐density fluid. As these flows are largely driven by slope, rather than by momentum, they are potentially capable of traveling great distances, producing extensive channel systems. We apply this process to Venus, exploring its channel‐forming potential via mathematical modeling and morphological comparison of submarine channels on Earth to canali on Venus. Results of our modeling show that atmospheric particulate gravity currents are physically and geologically plausible on Venus. The potential of this process to form channels of great length is such that particulate gravity currents can be considered as an alternate explanation for canali genesis.