lithospheric

Lithospheric, in geologic terms, refers to the lithosphere, the Earth's outer rigid shell that underlies continents and ocean basins. The lithosphere consists of the crust and the rigid portion of the upper mantle, and it behaves as a coherent, strong layer that floats on the underlying, more ductile asthenosphere. The term is used to describe properties, processes, and structures associated with this rigid shell.

Thickness and composition vary by region. Oceanic lithosphere typically ranges from about 60 to 100 kilometers in thickness, while continental lithosphere is thicker, roughly 150 to 250 kilometers, and can be even more extensive beneath stable cratons. The lithosphere includes both the crust (continental or oceanic) and the rigid lithospheric mantle. The base of the lithosphere transitions into the softer asthenosphere, and the boundary is not marked by a single sharp boundary but by changes in mechanical behavior. The Mohorovičić discontinuity (Moho) marks the crust–mantle boundary within the lithosphere.

Geophysical and geochemical properties underpin its role in plate tectonics. Oceanic lithosphere is composed mainly of basaltic crust and ultramafic mantle, and it becomes cooler and denser with age. Continental lithosphere carries granitic to rhyolitic crust atop a thick, buoyant lithospheric mantle. Its overall rigidity allows tectonic plates to move as distinct units relative to each other.

Dynamics and surface expression. The tectonic plates formed by the lithosphere enclose regions that interact at plate boundaries, producing earthquakes, volcanism, and mountain-building events. At divergent boundaries, plates move apart; at convergent boundaries, one plate may subduct beneath another; at transform boundaries, plates slide laterally. Subduction recycles lithospheric material into the mantle, influencing geochemical cycles and surface geology.