3D Convection Models with Plates

Here we present two models of time-dependent mantle convection which incorporate plates with fixed geometry. Plates are incorporated into the models through rheology. Two continents which are on the two sides are simulated as high viscosity lids with Newtonian rheology, while the two oceanic plates which are bounded by the two continents are modeled with non-newtonian rheology. There is a dipping fault between each pair of oceanic and continenental plates. Two oceanic plates are separated by two spreading centers and a transform fault which offsets the spreading centers. The two spreading centers are included as weak zones. The average viscosities for the top 100 km, the upper mantle, transition zones, and the lower mantle are about 5e23 Pa.s, 2e20 Pa.s, 4e21 Pa.s, and 2e22 Pa.s, respectively. The dimension of the box is 10500 km x 6000 km x 1500 km. The maximum temperature contrast in the models is 1600 K. The initial temperature in the mantle interiors is constant and is 1600 K higher than the surface temperature.

The first case includes an endothermic phase change (clapeyron slope: -3.5 MPa/K; density jump: 9%) at the 670 km. The second case differs from the first one only in excluding the phase change.

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Acknowledgments. Calculations were done on an Intel Paragon (512 nodes) parallel computer at Caltech.