AN ABSOLUTE PLATE MOTION MODEL BASED ON HOTSPOT REFERENCE FRAME

Abstract

Based on the new generation model of relative plate motions, the MOVEL model, an absolute plate motion model is built by least squares inversion of the observed hotspot trend data. A systematic test for the consistency between the MOVEL model and all the available hotspot data adopted by previous studies of absolute plate motion models shows there are outliers in the data set. Accordingly, two new methods to reject outliers, such as, step-wise rejection and global search rejection, are proposed. Combined with the chi-square test for the total residual and the normal test for the residual frequency distribution, the best model is selected step by step. A T87 model is eventually obtained. This model provides reasonable fitting to 87 globally distributed hotspot trends, but the predicted plate velocities are systematically lower than the observed rates of volcanic migration along hotspot tracks with the deviation up to 4 cm·a⁻¹. Such a deviation may be explained as a consequence of systematic errors possibly associated with the observed hotspot rate data, or due to relative motions between hotspots caused by mantle return flow. For either case, however, this study's results demonstrate that the hotspot trend data are capable of defining a global hotspot reference frame independently and effectively, which could be conveniently applied to studies on absolute plate motion, mantle convection and true polar wander.