A Glimpse At Titan's Geological History From Cassini Radar Data

We used data from the SAR mode of the Cassini RADAR to map the distribution and relative ages of terrains that allow us to determine the geological processes that have shaped Titan's surface. These SAR swaths cover about 20 percent of the surface, at a spatial resolution ranging from 350 m to about 2 km. The SAR data are distributed over a wide latitudinal and longitudinal range, enabling some conclusions to be drawn about the global distribution and significance of processes. They reveal a geologically complex surface that has been modified by all the major geologic processes seen on Earth - volcanism, tectonism, impact cratering, and erosion and deposition by fluvial and aeolian activity. In terms of global areal distribution, dunes and bright, hummocky, mountainous terrains cover more area than lakes, cryovolcanic features, mottled plains, and craters and circular structures that may be due to impact. Undifferentiated (unmapped) plains are the largest areal unit; their origin is uncertain. In terms of latitudinal distribution, dunes and hummocky and mountainous terrains are located mostly at low latitudes (less than 30 degrees), with no dunes being present above 60 degrees. Channels formed by fluvial activity are present at all latitudes, but lakes are found at high latitudes only. Circular structures that may have been formed by impact appear to be uniformly distributed with latitude, but the well-preserved impact craters are all located at low latitudes, possibly indicating that more resurfacing has occurred at higher latitudes. Cryovolcanic features, consisting mostly of flows, are not ubiquitous. We examine temporal relationships between units wherever possible, and conclude that aeolian and fluvial/pluvial/lacustrine processes are the most recent, while tectonic processes that led to the formation of mountains and Xanadu are likely the most ancient.