Publication Date:
2018-03-01
Description:
Lithospheric plates move over the low-viscosity asthenosphere balancing several forces, which generate plate motions. We use a global 3-D lithosphere-asthenosphere model (SLIM3D) with visco-elasto-plastic rheology coupled to a spectral model of mantle flow at 300 km depth to quantify the influence of intra-plate friction and asthenospheric viscosity on plate velocities. We account for the brittle-ductile deformation at plate boundaries (yield stress) using a plate boundary friction coefficient to predict the present-day plate motion and net rotation of the lithospheric plates. Previous modeling studies have suggested that small friction coefficients (μ 〈 0.1, yield stress ∽ 100 MPa) can lead to plate tectonics in models of mantle convection. Here we show that in order to match the observed present-day plate motion and net rotation, the frictional parameter must be less than 0.05. We obtain a good fit with the magnitude and orientation of the observed plate velocities (NUVEL-1A) in a no-net-rotation (NNR) reference frame with μ 〈 0.05 and a minimum asthenosphere viscosity of ∽ 5.1019 Pas to 1020 Pas. Our estimates of net rotation (NR) of the lithosphere suggest that amplitudes ∽0.1-0.2 (°/Ma), similar to most observation-based estimates, can be obtained with asthenosphere viscosity cutoff values of ∽ 1019 Pas to 5.1019 Pas and friction coefficients μ 〈 0.05. © 2018. American Geophysical Union. All Rights Reserved.
Electronic ISSN:
1525-2027
Topics:
Chemistry and Pharmacology
,
Geosciences
,
Physics
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