[DataPacRat]

May I just pause a moment to mention how pleased I am to be able to have this sort of discussion on this forum? ... Okay, I'm good. :)

Originally Posted by AlexanderHowl

The liquid water mantle cannot have a density above 1, as water cannot be compressed.

For pure water, that's true; but the reports I've been reading have suggested that Titan's liquid-water mantle is extremely salty, with the pop-sci articles referring to it as salty as "the saltiest seas on Earth", and mentioning the Dead Sea and its 40% salinity.

(Various reports have mentioned that the solutes likely include Cl -, HCO3 - (bicarbonate), and SO4 2- (sulphate); and Na +, Ca 2+, Mg 2+, K +, and NH4 2+ (ammonium). At the moment, I'm positing that at least one borehole was dug down to the subsurface ocean to un-dissolve some of those inorganic minerals for local industrial use.)

From what I have read

About all I can mention is what I've been reading myself, lately; here's the most relevant items from my browser's recent history:

https://elib.dlr.de/90334/1/2014-soh...jgre201246.pdf
https://cyber.sci-hub.tw/MTAuMTAxNi9...baland2014.pdf
https://zero.sci-hub.tw/1357/1dad0cc...fortes2012.pdf
https://www.lpi.usra.edu/meetings/lpsc2012/pdf/2939.pdf
https://www.hou.usra.edu/meetings/lpsc2014/pdf/2435.pdf
http://www2.ess.ucla.edu/~jewitt/cla...rs/Wood_10.pdf
https://agupubs.onlinelibrary.wiley....9/2010GL044398

, the current research on Titan suggests that 50% of its mass is in rocky material while 50% of its mass is in volatile materials. Since Titan possesses expansion fractures rather than compression fractures, it is constantly renewing its surface through cryovolcanism rather than shrinking.

I spent last evening mostly focusing on Titan's subsurface ocean; looks like tonight, I'll be expanding my search parameters to cryovolcanoes and stress fractures.

A possible structure is an icy volatile crust over a carbon rich slurry over a liquid water mantle over a rocky core.

Might I ask where you found that proposal? Pretty much every paper I've found suggests layers of icy crust, liquid water, high-pressure ice, and rocky core. (With most of the disagreements being on the layers' thicknesses, and various details about the core.)

The kinetic energy during its rapid formation (probably over 30,000 years) would have generated massive amounts of heat that became trapped by icy volatile crust (similar to the most recent research on the formation of Pluto). Precipitation of ice, radioactive decay from the rocky core, and tidal energy from its moderately eccentric orbit around Saturn would have maintained the total heat in the system, resulting in a rich place for a strange life.

The warm water mantle creates plumes of liquid water the rise up through the carbon slurry and melts through the icy crust. Where the water does not quite come to the surface, the added heat allows for carbon slurry geysers. When the water reaches the surface, it creates water volcanoes that replenish the surface ice. Since Titan has a young surface similar to the Earth's, it probably possesses equivalent levels of volcanic activity.

A rocky core with a density of 5.6 grams per cubic centimeter and a radius of 1500 km would produce enough thermal energy through radioactive decay to maintain the liquidity and warmth of a 800-900 km thick water mantle for billions of years, with the added energy from precipitation and tidal flexing. While a moon like Titan could have a less dense larger core, it becomes much harder for Titan to maintain a liquid core without unusual amounts of radioactive decay. A thicker water mantle also allows for more insulation, which would retain the heat from the initial formation longer, requiring only normal amounts of radioactive decay.

Any suggestions on how common the geysers and volcanoes would be? I'm wondering how consistent any of the underlying warm-water plumes would be; for instance, to figure out how often any particular settlement might be threatened by some new geology, and/or how often some active interventions down in the ocean might be needed to nudge a plume towards a less disruptive exit point.