April 14, 2017 @ 12:00 pm - 12:50 pm CDT
Who: Chengzu Wang
When: Noon, Friday, April 14, 2017
Where: Room 100, KWGL
What: “Rates of Motion of Groups of Hotspots Estimated from the Dispersion
of Hotspot Trends”
Abstract: “While it is widely believed that groups of hotspots in different regions of the world are in relative motion at rates of 10 to 30 mm a-1 or more, recent work on plate motions over the past ≈50 Ma indicate no significant motion between hotspots beneath different plates and furthermore place an upper bound on such motion of ≈10 mm a-1. Here we further examine this question. We present a new method for analyzing geologically current motion between groups of hotspots beneath different plates. In an inversion of 56 globally distributed, equally weighted trends of hotspot tracks, misfit magnitudes range from 0° to 83° (median= 9°; σ=23°). The dispersion is dominated by differences in trend between different plates rather than differences within plates. The absolute value of mean angular difference for a given plate decreases significantly with increasing absolute plate speed. When these angular misfits are converted to vperp, the rate of hotspot motion perpendicular to the direction of absolute plate motion, there is no significant dependence on absolute plate speed. Moreover, vperp differs significantly from zero for only three of ten plates and then by merely 0.3 to 1.4 mm a-1. The overall mean upper bound on |vperp| is 3.2 ±2.7 mm a–1. Therefore, in the direction perpendicular to plate motion, groups of hotspots move slowly, merely 0.5–5.9 mm a-1, relative to the mean hotspot frame, much slower than found in most prior work”.