Kiladze Caldera: A possible "supervolcano" on Pluto

In data from the New Horizons encounter with Pluto in 2015, attention was called to a crater named Kiladze and its surroundings because of the water ice spectral properties, which contrast with the primarily CH4 regional surface composition. The H2O ice carries the spectral signature of an ammoniated compound, similar to that seen at two other sites on Pluto where cryovolcanism has been identified. The faulted structure of Kiladze, including shaping by numerous collapse pits and the distorted shape of the crater, are compatible with the surroundings in Hayabusa Terra, east of Spunik Planitia. They are compatible with an interpretation as a resurgent caldera formed in a once- active cryovolcanic period that appears to be significantly more recent than the overall age of the planet's surface, possibly in the last several million years. In view of the size of the caldera and the large scale of the surrounding distribution of H2O ice, we propose that Kiladze is a "supervolcano" in which one or more explosive events has scattered more than ~1000 km3 of icy cryomagma erupted from the interior onto the surface.