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DRIVING FORCES FOR LITHOSPHERIC DEFORMATION |
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The forces acting on a lithospheric plate have three possible origins: 1/ mantle convection, 2/ plate tectonic processes, and 3/ lateral variation in gravitational potential energy. The picture below shows the forces acting on a subducting oceanic lithosphere and the overriding continental lithosphere. The force Fa, acting of the slab, is related to motion of asthenospheric material therefore to convection. The force Fo acting on the overriding plate results from the combination of the ridge push force (Frp) and the slab pull force (Fsp). Both forces are related to the creation and destruction of oecanic lithosphere, therefore to plate tectonic processes. The force of suction (Fsu) pulls the continental lithosphere toward the trench. This force includes the horizontal gravitational force (Fh) that results from lateral variation in gravitational potential energy. In the case illustrated here the horizontal forces acting of the overriding continental lithosphere are responsible for its thickening. |
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