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Published February 10, 1999 | public
Journal Article

How valid are dynamic models of subduction and convection when plate motions are prescribed?

Abstract

A detailed comparison between fully dynamic and kinematic plate formulations has been made in models of mantle convection. Plate velocity is computed self-consistently from fully dynamic plate models with temperature- and stress-dependent viscosity and preexisting mobile faults. In fully dynamic models, the flow is driven solely by internal buoyancy, while in kinematic models the flow is driven by a combination of the prescribed surface velocity and internal buoyancy. Only a temperature-dependent viscosity, close to the effective viscosity determined from the fully dynamic models, is used in the kinematic models. The two types of models give very similar temperature structures and slab evolutionary histories when the effective viscosity and surface velocity are nearly identical. In kinematic plate models, the additional work introduced by the prescribed velocity boundary condition is apparently dissipated within the lithosphere and has little influence on the convection under the lithosphere. In models with periodic lateral boundary conditions, slabs sink into the lower mantle at an oblique angle and this contrasts with the vertical sinking which occurs with reflecting boundary conditions. Models show that we can simulate fully dynamic models with kinematic models under either periodic boundary conditions or reflecting boundary conditions.

Additional Information

© 1999 Elsevier Science B.V. Received 15 June 1998; revised 6 October 1998; accepted 6 October 1998. The authors wish to thank S. Zhong for providing us with the finite element code used for fault calculations and U. Christensen and S. King for helpful comments on the manuscript. The work was supported by NSF grant EAR-9614391 and represents Contribution Number 8540 of the Division of Geological and Planetary Sciences, California Institute of Technology.

Additional details

Created:
August 22, 2023
Modified:
October 23, 2023