Cryovolcanism and Degassing on Titan, a Moon of Saturn

This paper considers the occurrence, diversity, and special features of volcanic and degassing processes on Titan, as well as analyzing the maximum gas concentrations of volatiles in a vertical profile of its interior and atmosphere. We showed that the specific character of Titan volcanic and degassing processes is due to low temperatures, a peculiar material composition, and the ubiquitous presence of a subsurface liquid horizon. Consequently, the common (on Earth) forms of (cryo)volcanic activity are reduced, while the more common forms include (1) gas-lifting degassing, which produces numerous, small, depressions with a higher level of liquid, and which is a probable cause of “magic islands” in Ligeia Mare, as well as (2) limnological discharges of gaseous methane with subsequent intensive cloud formation, occurrence of methane storms, and large-volume precipitation. In turn, both gas-lifting degassing and limnological discharges of endogenous methane are due to the condensate–gas inversion at depths of 1–2 km in Titan’s interior. Below that depth, the endogenous fluids are nearly all gasless condensates, while above, these condensates start intensive boiling. We conclude that degassing is the most important relief-forming factor on Titan.