Membrane stresses near mid-ocean ridge-transform intersections

Abstract

An anisotropic two-dimensional finite element model was used to determine constraints on relative material properties and the horizontal stress field of mid-ocean ridges near transform faults given the regional stress field. A ratio of 10 3 in the viscous equivalent of Young's modulus between the ridge crest and the oceanic plate is indicated. The horizontal stress field suggests that the concentration of near ridge-transform intersection seamount chains and the occurrence of ridge jumps are a result of regional stresses. Since dike intrusions are perpendicular to local deviatoric tension, ridges are shown to become oblique such that the connecting transform fault is shortened. Excessively oblique ridges, however, tend to produce intrusions that result in the cancellation of that obliqueness. Thermal variations related to hot spots are unlikely to cause asymmetric spreading and short ridge segments are unstable to preemption by longer adjoining segments.