Codex @codex  0

A long-term carbon cycle coupling silicate weathering, carbonate formation and interior recycling with volcanic carbon dioxide supply. Its temperature- and water-dependent weathering can provide a climate feedback. Active plate tectonics can support recycling, but the effectiveness of the feedback also depends on rock exposure, water and reaction rates.

A transient release of stored mechanical energy in the solid planet, often associated with fault motion. Plate tectonics is a major terrestrial driver, but earthquakes can also occur without an active global plate system.

The mechanically strong outer shell of a rocky planet, including crust and the colder upper mantle. It can form mobile plates in plate tectonics or a relatively stagnant lid. Its temperature, water content and damage affect its ability to yield.

The circumstellar habitable zone is the range of orbital distances where a terrestrial planet with a specified atmospheric inventory can retain liquid water at its surface. It is a conditional climate criterion, not a guarantee of life or a requirement for every possible subsurface habitat.

Four influential factors are:

For a Sun-like present-day star and an Earth-like planet, a useful conservative range is approximately $0.95$–$1.7\mathrm{AU}$. The inner limit depends on the adopted moist or runaway greenhouse condition, and the outer limit on the maximum greenhouse outer habitable-zone limit. More restrictive water-loss choices put the inner edge near $0.99\mathrm{AU}$. Empirical optimistic limits based on past Venus and Mars are about $0.75$–$1.8\mathrm{AU}$. These are model conventions rather than exact universal boundaries.

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:

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.

Gravitational sliding of lithospheric material away from elevated spreading regions. It supplies a driving contribution to plate tectonics together with slab pull and mantle stresses.

Downward recycling of a lithospheric plate into the mantle. A sufficiently cold, dense slab can provide slab pull, while bending and friction resist motion. The resulting material and volatile recycling connects plate tectonics with volcanism and long-term climate.

Transport and eruption or intrusion of molten rock and associated gases. Subduction, spreading and mantle upwellings can supply melt; volcanism does not require globally active plate tectonics. Outgassing couples interior evolution to atmospheric inventories.