ORIGIN OF OVERLAPPING SPREADING CENTERS - A FINITE-ELEMENT MODEL

Overlapping spreading centers (OSCs) appear to result from two ridges propagating head‐on toward each other. The origin of the most elongated and the largest ones is almost perfectly accounted for by the stresses due to the relative elevation of the tips of the propagating ridges rather than to the elevation of the whole ridges (ridge push); on the other hand, stresses due to the ridge push, or to the forcible injection of magma at stationary centers, produce wider OSCs than those on the East Pacific Rise between 3°N and 13°N. We conclude that cross sections of ridges more than a few kilometers away from spreading centers are essentially in a state of plane stress. Our modelling method uses the finite element method and dynamic fracture propagation; the mesh is modified at every time step to minimize computational errors. Copyright 1990 by the American Geophysical Union.