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Published September 19, 1996 | public
Journal Article

Interaction of weak faults and non-newtonian rheology produces plate tectonics in a 3D model of mantle flow

Abstract

According to the theory of plate tectonics, relatively rigid plates are bounded by large faults; plate motion has negligible internal strain,with significant toroidal component to the velocity. By contrast, models of mantle flow with viscous rheology in an intact medium predict little toroidal component and substantial internal strain in surface motion. It has been suggested5 that the observed characteristics of plate motion are related to faulted plate margins, which are observed to be weak. Here we confirm this suggestion, using three-dimensional models of mantle flow that incorporate faults and the forces exerted on plates by subducting slabs ("slab pull') and mid-ocean ridges ('ridge push'). Our models show that plate-like motion results from the interaction between weak faults and a strain-weakening power-law rheology. Weak transform faults tend to guide plate motion. This guiding effect and the decoupling that occurs at thrust faults may result in oblique subduction. Convergent margins are associated with realistic trench and fore-bulge topography. By simultaneously predicting surface kinematics, topography and gravity, the models achieve a useful degree of tectonic realism.

Additional Information

© 1996 Nature Publishing Group. Received 12 January; accepted 6 August 1996. We thank L. Moresi for providing the CITCOM software on which our fault algorithm is built, and U. Christensen, C. Gable and M. Simons for helpful reviews. This work was supported by the US NSF and the David and Lucile Packard Foundation.

Additional details

Created:
August 19, 2023
Modified:
October 23, 2023