Absolute plate motions constrained by shear wave splitting orientations with implications for hot spot motions and mantle flow

Abstract

[1] Here, I present a new absolute plate motion model of the Earth's surface, determined from the alignment of present-day surface motions with 474 published shear wave (i.e., SKS) splitting orientations. When limited to oceanic islands and cratons, splitting orientations are assumed to reflect anisotropy in the asthenosphere caused by the differential motion between lithosphere and mesosphere. The best fit model predicts a 0.2065°/Ma counterclockwise net rotation of the lithosphere as a whole, which revolves around a pole at 57.6°S and 63.2°E. This net rotation is particularly well constrained by data on cratons and/or in the Indo-Atlantic region. The average data misfit is 19°and 24°for oceanic and cratonic areas, respectively, but the normalized root-mean-square misfits are about equal at 5.4 and 5.2. Predicted plate motions are very consistent with recent hot spot track azimuths (<8°on many plates), except for the slowest moving plates (Antarctica, Africa, and Eurasia). The difference in hot spot propagation vectors and plate velocities describes the motion of hot spots (i.e., their underlying plumes). For most hot spots that move significantly, the motions are considerably smaller than and antiparallel to the absolute plate velocity. Only when the origin depth of the plume is considered can the hot spot motions be explained in terms of mantle flow. The results are largely consistent with independent evidence of subasthenospheric mantle flow and asthenospheric return flow near spreading ridges. The results suggest that, at least where hot spots are, the lithosphere is decoupled from the mesosphere, including in western North America.

Crust-mantle mechanical coupling in Eastern Mediterranean and Eastern Turkey

“…their associated delay times decrease from the east to the west. The average direction of splitting is roughly similar to the APM of western Eurasia (19,46). In eastern Turkey the mantle lithosphere is largely missing (47, 48) because of delamination and slab break-off around 11 Mya.…”

“…A c. 20 mm∕y rightlateral strike-slip motion along the North Anatolian Fault Zone (NAFZ) and 9 mm∕y left-lateral motion along the East Anatolian Fault (EAF) accommodate the westward escape of Anatolia. The GPS velocity field from a dataset I compiled from several sources (3,(11)(12)(13)(14)(15)(16)(17) and four IGS stations (GPSVELv1.0) (18) with respect to GSRM-APM-1, an Absolute Plate Motion (APM) reference frame (19), is given in Fig. 1.…”

Three‐dimensional dynamic models of subducting plate‐overriding plate‐upper mantle interaction

“…We do not prefer the Pacific hotspot reference frame from Gripp and Gordon [] that is used by Heuret et al [] because we think it shows a net global rotation of the lithosphere with respect to the underlying mantle that is too high (0.44°/Ma counterclockwise rotation around a pole at 56°S, 70°E). Constraints based on mantle anisotropy give a much lower global net rotation of the lithosphere (0.2065°/Ma counterclockwise rotation around a pole at 57.6°S, 63.2°E) [ Kreemer , ].…”

Mantle constraints on the plate tectonic evolution of the Tonga–Kermadec–Hikurangi subduction zone and the South Fiji Basin region

“…Schellart et al 2008;Kreemer 2009;Conrad & Behn 2010;Schellart 2011), indicating that Indo-Atlantic moving hotspot reference frames, with minor net westward lithosphere rotation, are in better agreement with observations and geodynamic inferences than a number of Pacific fixed hotspot reference frames, which Figure 12 Comparison between predicted Tonga-Kermadec-Hikurangi slab anomalies subducted at 45-30 Ma and observed high-velocity P-wave tomography anomalies at 1200 km depth, with (a) model 2RS, (b) model CRS, and (c) model ACRS. Predicted slab anomalies have plotted using the Pacific fixed hotspot reference frame from Wessel & Kroenke (2008).…”