litosfärens

The lithosphere, referred to in some languages as litosfærens, is the rigid outer shell of the Earth. It comprises the crust and the uppermost mantle, and it is structurally distinct from the underlying, more ductile asthenosphere. The lithosphere is divided into two major types: continental lithosphere, which is thicker and less dense and mainly made of granitic rocks; and oceanic lithosphere, which is thinner, more dense, and primarily composed of basaltic rocks.

The base of the lithosphere is marked by the lithosphere–asthenosphere boundary (LAB). This boundary lies at varying depths, commonly around 100–200 kilometers beneath oceans and up to about 250 kilometers beneath some continental regions, depending on temperature and composition. The Mohorovičić discontinuity (Moho) marks the crust–mantle boundary within the lithosphere, separating crustal rocks from mantle rocks.

The lithosphere is mechanically rigid and does not flow like the asthenosphere beneath it. This rigidity allows it to break into tectonic plates that move relative to one another due to convection in the mantle. Plate tectonics explains much of the Earth’s surface dynamics, including earthquakes, volcanism, mountain building, and the creation and destruction of ocean basins. Plate interactions occur at divergent, convergent, and transform boundaries, producing diverse geologic phenomena.

Compositionally, the lithosphere is dominated by silicate rocks: granitic compositions in continental regions and basaltic compositions in oceanic regions. Its behavior and evolution influence surface topography, geochemical reservoirs, and the thermal evolution of the planet.