A lobate feature adjacent to a double ridge on Ariel: Formed by cryovolcanism or mass wasting?

Abstract

We identified a large-scale lobate feature that is proximal to a double ridge on Ariel. We analyzed the morphology of this feature to investigate whether it was formed by cryovolcanism or mass wasting. Our results show that the head of the lobate feature is adjacent to a topographically elevated dome on the double ridge, which may have formed via extrusion and emplacement of cryolava in this location. We find that the coefficient of friction of the material that formed the lobate feature is more consistent with a cryovolcanic flow than either a dry or liquid-aided mass wasting flow. Similarly, the estimated yield strength for the neck and terminus of this feature is similar to geologic features that contained some liquid during formation. Alternatively, upwelling of material, in an ascending diapir, could also explain the morphology of this lobate feature, in particular its topographically elevated terminus, which is higher standing than its neck. Higher resolution images are needed to assess the surface texture of the lobate feature to further investigate whether it formed via flowing cryolava or diapirism. Furthermore, without higher spatial resolution images, the possibility of a mass wasting origin for the lobate feature cannot be ruled out and warrants further investigation. The possible presence of cryovolcanic features on Ariel supports the interpretation that this moon is a candidate ocean world that has, or had, a subsurface liquid water layer beneath its icy exterior.