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How would plate tectonics work on these planets?

Posted: 16 May 2017 20:17
by spaceguy
I'm especially wondering about the tidally locked planet...

How would plate tectonics work on these planets?

Posted: 16 May 2017 21:26
by Watsisname
My guess would be about the same as on any other terra.  Plate tectonics is based on mantle convection, which is slow and does not care a whole lot about the planet's rotation rate.

How would plate tectonics work on these planets?

Posted: 17 May 2017 05:21
by spaceguy
Watsisname wrote:
My guess would be about the same as on any other terra.  Plate tectonics is based on mantle convection, which is slow and does not care a whole lot about the planet's rotation rate.

What I meant was, how does plate activity interact with the cryosphere in the photos above which appears many kilometers thick and doesn't seem to have any deformations at all.

How would plate tectonics work on these planets?

Posted: 17 May 2017 05:49
by Mosfet

How would plate tectonics work on these planets?

Posted: 17 May 2017 16:58
by Watsisname
Ooh, good link!

Wikipedia wrote:
External sources of planetary heat (namely, radiation from a planet’s host star) can have drastic effects on geodynamic regime. With all other variables held constant, an Earth-sized exoplanet with a surface temperature of 273 K will evolve over its geological lifetime from a plate tectonic regime, to episodic periods of plate tectonics interspersed with stagnant lid geodynamics, to a terminal stagnant lid phase as interior heat is exhausted. Meanwhile, a “hot” planet (759 K surface temperature) under the same initial conditions will have an amorphous surface (due to lithospheric yield stress being constantly exceeded) to a stagnant lid as interior heat is exhausted, with no plate tectonics observed.[5]

Planets closer than 0.5 astronomical units from their star are likely to be tidally locked; these planets are expected to have drastically different temperature regimes on their “day” and “night” sides. When this scenario is modeled, the day side displays mobile lid convection with diffuse surface deformation flowing toward the night side, while the night side has a plate tectonic regime of downwelling plates and a deep mantle return flow in the direction of the night side. A temperature contrast of 400 K between day and night sides is required to create such a stable system


This is very interesting.  I did not know the temperature difference across the planet, if sufficiently large, could have such an effect. :)  I'll have to add the paper that comes from to my reading list.

How would plate tectonics work on these planets?

Posted: 19 May 2017 15:16
by problemecium
Interesting indeed o_O I never would have expected that a thin crust could have significant effects on what the mantle is doing, given the square-cube law and the sizes involved.

P.S. WTF Forum, you log me out in the middle of typing a post?