A mechanical model for the inside corner uplift at a ridge-transform intersection

At least part of the inside corner uplift observed at slow ridge-transform intersections is shown to be a consequence of the flexure of an elastic plate caused by a twisting moment exerted along the transform fault. The frictional drag exerted along the transform increases with depth (overburden) down to the depth where plastic flow predominates; this depth-dependent drag results in a moment applied to the edge of the plate. An uplift of an inside corner of several hundred meters can be obtained by this mechanism. This can be increased to roughly 1 km (the observed uplift at some intersections) if we assume the elastic thickness of the plate is effectively thinner because of relaxation by long-term creep of the stresses resisting plate flexure. Simple models formulated to test this hypothesis show that the observed inside comer uplift of the Vema and Oceanographer transforms can be explained if the “effective elastic thickness” of the plate is about half of the thickness over which drag increases with depth along the transform fault boundary.