DATING TRITON’S SURFACE: IT’S COMPLICATED

Triton, Neptune’s largest moon, is a world that likely hosts an ocean beneath its icy shell. The surface has been observed by the Voyager 2 spacecraft to be active in the form of numerous plumes emanating from the region near its south pole. Most terrains appear to be young with a dearth of craters while others show evidence for possible recent cryomagmatic activity. Much of this youthfulness and activity could be attributed to Triton’s evolutionary history as a purported captured Kuiper Belt object. We will present our efforts to determine the relative ages of the multiple geological units we have identified on the surface as we complete the USGS SIM. We have identified 11 broad terrain units that are then divided into subunits. The broad units consist of cantaloupe terrain, crater materials, cellular terrain, guttae, linear ridges, lobate terrain, patera, pitted terrain, smooth terrains, southern hemisphere terrains, and walled terrains. These terrains differ in their areal extent, location on the surface, number of craters visible on the surface, relative brightness, and texture. Some units clearly cut into older ones, while other unit boundaries are more ambiguous. Here we present our interpretation of the relative ages of all these units including evidence for a more youthful age for the Cantaloupe terrains and an older relative age for the linear ridges than previously suggested.