Evaluating the Influence of Plate Boundary Friction and Mantle Viscosity on Plate Velocities. (10th March 2018)

• Record Type: Journal Article
• Authors: Osei Tutu, A.; Sobolev, S. V.; Steinberger, B.; Popov, A. A.; Rogozhina, I.
• Is Part Of: Geochemistry, geophysics, geosystems. Volume 19:Number 3(2018)
• Page Start: 642
• Page End: 666
• Publication Date: 2018-03-10
• Subjects: lithosphere‐asthenosphere coupling with mantle convection -- upper mantle rheology -- lithosphere net rotation -- plate motion -- plate boundary friction -- water content in asthenosphere; Geochemistry -- Periodicals; Geophysics -- Periodicals; Earth sciences -- Periodicals; 550.5
• DOI: 10.1002/2017GC007112
• Languages: English
• ISSNs: 1525-2027

Abstract

Abstract: 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 · 10 19 Pas to 10 20 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 ∼ 10 19 Pas to 5 · 10 19 Pas and friction coefficients μ < 0.05 . Key Points: We model plate motions using a global model that combines a 3‐D visco‐elasto‐plastic rheology in the upper 300 km and a radial viscosity structure in the mantle We estimate interplate friction and upper mantle viscosity to reproduce observed plate velocities as well as the magnitude and location of the Euler pole of lithosphere net rotation Key parameters required to fit observations are a friction coefficient of less than 0.05 at plate boundaries and a minimum mantle viscosity cut‐off of 1–5 · 10 19 Pas