A RELATIVE TIMING SEQUENCE FOR TRITON’S GEOLOGIC HISTORY

Voyager 2’s encounter with the Neptune system returned images of its largest moon (~1350 km radius), Triton. These 40 year old images remain the primary data for our understanding of that dynamic satellite. Triton has a young surface with very few craters, and is geologically active with plumes emanating from the surface. The activity has been linked to its dynamical orbital history as a likely captured Kuiper Belt Object (KBO). The capture of Triton by Neptune, likely resulted in a massive heating event that resulted in resurfacing, possibly by cryovolcanism.

We are producing a USGS Scientific Investigations Map of the Neptune-facing side of Triton at 1:5M. The available imagery used for mapping covers approximately 1/3 of Triton’s total surface, a region between ~45°S to ~60°N latitude and ~-75° to ~90°E longitude. Our geologic map characterizes, classifies, and identifies geologic surface units across Triton and enables a first order approximation of the timing of the emplacement of the geological structures and terrain units.

We identify at least 12 terrain units including cantaloupe terrains (the result of possible diapirism) and southern hemisphere terrains where many dark, wispy plume deposits have been preserved. The eastern portion of our map contains circular structures that have previously been considered as possible volcanic structures. We will present our final terrain units and a preliminary stratigraphy that will place the visible portion of Triton’s surface into a relative geologic timeline.