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How mantle convection directly and indirectly relates to plate motion is a matter of ongoing study and discussion in geodynamics. Somehow, this energy must be transferred to the lithosphere for tectonic plates to move. There are essentially two main types of mechanisms that are thought to exist related to the dynamics of the mantle that ...
The tectonic plates of the lithosphere on Earth Earth cutaway from center to surface, the lithosphere comprising the crust and lithospheric mantle (detail not to scale). A lithosphere (from Ancient Greek λίθος (líthos) 'rocky' and σφαίρα (sphaíra) 'sphere') is the rigid, [1] outermost rocky shell of a terrestrial planet or natural satellite.
Beneath the Earth's crust lies the mantle which is heated by the radioactive decay of heavy elements. The mantle is not quite solid and consists of magma which is in a state of semi-perpetual convection. This convection process causes the lithospheric plates to move, albeit slowly. The resulting process is known as plate tectonics.
The lithospheric mantle is the portion of the lithosphere within the mantle, as opposed to the crust. It is solid, and is the uppermost part of the mantle.
The lithosphere is divided into tectonic plates that are continuously being created or consumed at plate boundaries. Accretion occurs as mantle is added to the growing edges of a plate, associated with seafloor spreading. Upwelling beneath the spreading centers is a shallow, rising component of mantle convection and in most cases not directly ...
The pressure at the bottom of the mantle is ≈140 GPa (1.4 Matm). [24] The mantle is composed of silicate rocks richer in iron and magnesium than the overlying crust. [25] Although solid, the mantle's extremely hot silicate material can flow over very long timescales. [26] Convection of the mantle propels the motion of the tectonic plates in the
Extension in the plate is a consequence of deformation at plate boundaries, thermal contraction, and isostatic adjustment. Extension originated at a spreading ridge around 80 Ma. The plate's stress field evolved over the next 30 million years, causing the region of extension and consequent volcanism to migrate south-southeast.
The asthenosphere is the ductile region of the upper mantle. Mantle processes which operate across mountain belts include those related to subduction (e.g., slab break-off, flat-slab subduction, subduction of a triple junction). Volcanism is driven by mantle processes such as partial melting and thermal convection currents.