litosferei

The lithosphere, sometimes referred to in various languages as litosferei, is the rigid outer shell of the Earth. It comprises the crust and the rigid part of the upper mantle, forming plates that move over the underlying, more ductile asthenosphere. The base of the lithosphere is defined by the lithosphere–asthenosphere boundary (LAB), while the crust–mantle boundary is marked by the Mohorovičić discontinuity (Moho).

Depth and composition:

Continental lithosphere is thicker and less dense, typically about 100–300 kilometers thick, with crust dominated by granitic rocks. Oceanic lithosphere is thinner and more dense, usually about 60–100 kilometers thick, composed mainly of basaltic and gabbroic rocks. The lithosphere ends where rocks begin to deform plastically and move more easily in the mantle.

Dynamics:

The lithosphere is segmented into tectonic plates that float on the partially molten asthenosphere. Plate motions are driven by mantle convection, slab pull, and ridge push. Interactions at plate boundaries give rise to diverse geological phenomena: divergent boundaries create new lithosphere at mid-ocean ridges; convergent boundaries involve subduction or continental collision and are associated with earthquakes and volcanism; transform boundaries involve lateral sliding of plates.

Geological significance:

The lithosphere is central to plate tectonics, explaining the distribution of continents and ocean basins, mountain belts, and seismic activity. Its recycling at subduction zones and its interactions with the mantle drive long-term geodynamic and geochemical evolution of Earth.