Printable Version of Topic

Posted by: stevesliva Jan 13 2024, 01:25 AM

Generic thread title, struggled with where to put this.

https://www.utsa.edu/today/2024/01/story/professor-discovery-new-reality-on-saturns-moon.html

Posted by: HSchirmer Jan 13 2024, 04:11 PM

Perhaps a general topic of "weird density effects of cryo-geology"?

While not quite the floating mountains of YES-album-cover-art / Patrick Woodroffe, or the Avatar's movies Halleluiah-Mountains on Pandora, you do see something similar on Pluto with the shards of the al-Idrisi ice-mountains floating away across a lugubrious nitrogen sea...

A meteorologic cycle on Titan involving methane/ethane snow & slush raises some REALLY interesting opportunities for organic chemistry, catalysts, and daisy chaining catalytic loops to create tholins. See "Origins of Order" and other works on complexity theory from Santa Fe Institute and prebiotic autocatalytic networks...
It helps to think of the rich mix of 'ices' which make up the minerals from earth. Starting from a molten ball of magma containing metal oxides (MgO, CaO, K2O, Na2O) and silica oxide SiO2; as things cool you freeze out metal-oxide "ices" as basalt and silica-oxides "ices" as quartz. Subduction from plate tectonics introduces H2O under high pressure and temperature which further 'crack/catalyze' the minerals and refine then into a low-density silicate rich continental crust floating on a high-density basalt rich oceanic crust. Crustal minerals are exposed to atmospheric weathering, which converts silica crystals into polycyclic sheets clays. Eventually, flowing liquid collects tiny flecks of all these minerals and dumps them into a riverine delta containing millions of different mineral crystals (e.g. catalysts) and these tiny sedimentary grains gain an enormous surface area, creating the perfect place for liquid phase catalytic chemistry.

We should expect essentially the same processes on Titan, just with a different set of 'ices' and probably clathrates instead of clays. That's the really mind-blowing part, thinking about the sorts of 'igneous', 'sedimentary', and 'metamorphic' rocks you'd expect to see, when rocks are made out of materials that we breath in here on Earth.

Posted by: ngunn Jan 14 2024, 05:56 PM

This is a great reminder of just how many new puzzles the Cassini data from Titan opened up. I have always thought that some kind of floating pumice-like material was a strong candidate for the magic islands. The material's composition is fertile ground for speculation, as is the question of whether it snowed from above, calved from the shore or floated up from the sea bed.

Posted by: Bill Harris Jan 28 2024, 06:49 AM

HSchirmer, relating terrestrial magma to the rich ices on Titan is a brilliant observation. I'll need to read up on that.
The Dragonfly mission will answer so many questions about Titan as well as raise so many more.

--Bill

Posted by: HSchirmer Jan 29 2024, 12:01 PM

Thanks, although this analogy was pointed out to me a long time ago, when I was helping U-Penn botanists and a Penn-State geologist get landowner permission for biodiversity surveys.

The geologist was interested in the contact zone between intrusive diabase and shales, especially the grain sizes and crossbedding at the bottom of the magma chamber.
When I asked about fine layering and bedding in the diabase, the geologist explained that the magma chamber was like a snow-globe; the layers I was seeing in solid rock were mineral crystals that 'snowed out' as the magma chamber cooled, blown into drifts by convection currents, which eventually avalanched down the sides of the magma chamber to form the swirling pattern that was now set in stone.

Amazing to perceive an 'estuary' of mineral grains in a magma chamber, with different generations of mineral grains snowing down as the liquid cools and minerals fractionate out.