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 Incoming links: Ridge push

Plate tectonics is the movement and recycling of a planet's lithosphere as discrete plates over a deformable mantle. Mantle convection, the negative buoyancy of cool subducting slabs (slab pull), and gravitational sliding from elevated spreading ridges (ridge push) supply driving stresses; deformation and friction resist motion. The mantle mostly deforms by slow solid-state creep, rather than being a global liquid layer.

Its effects include subduction and recycling of crust, creation of new crust, mountain building, earthquakes and volcanism, transport of internal heat, and recycling of water and carbon. The carbonate-silicate cycle can couple volcanic CO2 supply to weathering and long-term climate.

Three major controls on a super-Earth's tectonic mode are:

Mass and pressure-dependent material behavior: gravity and mantle depth affect buoyancy and convective stresses, but high-pressure changes in viscosity and density also affect whether slabs sink.
Thermal state and heat budget: age, radiogenic heating, residual formation heat and surface temperature set convective vigor, plate thickness and the strength of the lid.
Water and lithospheric weakening: hydration, rock rheology, fault damage and yield strength determine whether driving stresses can break and recycle the lithosphere rather than leave a stagnant lid.

A larger mass alone does not establish active plate tectonics. The competition between driving stress, yielding and sustained slab buoyancy must be evaluated for the planet's composition and thermal history.

A mobile-lid mode of planetary evolution in which coherent pieces of the lithosphere move, form at spreading regions and can recycle through subduction. Slab pull, ridge push and mantle flow compete with deformation resistance. It affects heat transport, volcanism, earthquakes and the carbonate-silicate cycle. It is not guaranteed solely by an exoplanet's mass.