Tectonic speed limits from plate kinematic reconstructions

Abstract

Editor: Y. Ricard Keywords: RMS plate velocities plate reconstructions continent and craton speedsThe motion of plates and continents on the planet's surface are a manifestation of long-term mantle convection and plate tectonics. Present-day plate velocities provide a snapshot of this ongoing process, and have been used to infer controlling factors on the speeds of plates and continents. However, present-day velocities do not capture plate behaviour over geologically representative periods of time.To address this shortcoming, we use a plate tectonic reconstruction approach to extract time-dependent plate velocities and geometries from which root mean square (RMS) velocities are computed, resulting in a median RMS plate speed of ∼4 cm/yr over 200 Myr. Linking tectonothermal ages of continental lithosphere to the RMS plate velocity analysis, we find that the increasing portions of plate area composed of continental and/or cratonic lithosphere significantly reduces plate speeds. Plates with any cratonic portion have a median RMS velocity of ∼5.8 cm/yr, while plates with more than 25% of cratonic area have a median RMS speed of ∼2.8 cm/yr. The fastest plates (∼8.5 cm/yr RMS speed) have little continental fraction and tend to be bounded by subduction zones, while the slowest plates (∼2.6-2.8 cm/yr RMS speed) have large continental fractions and usually have little to no subducting part of plate perimeter. More generally, oceanic plates tend to move 2-3 times faster than continental plates, consistent with predictions of numerical models of mantle convection. The slower motion of continental plates is compatible with deep keels impinging on asthenospheric flow and increasing shear traction, thus anchoring the plate in the more viscous mantle transition zone. We also find that shortlived (up to ∼10 Myr) rapid accelerations of Africa (∼100 and 65 Ma), North America (∼100 and 55 Ma) and India (∼130, 80 and 65 Ma) appear to be correlated with plume head arrivals as recorded by large igneous province (LIPs) emplacement. By evaluating factors influencing plate speeds over the Mesozoic and Cenozoic, our temporal analysis reveals simple principles that can guide the construction and evaluation of absolute plate motion models for times before the Cretaceous in the absence of hotspot tracks and seafloor spreading histories. Based on the post-Pangea plate motions, one principle that can be applied to pre-Pangea times is that plates with less than ∼50% continental area can reach RMS velocities of ∼20 cm/yr, while plates with more than 50% continental fraction do not exceed RMS velocities of ∼10 cm/yr. Similarly, plates with large portions of continental or cratonic area with RMS velocities exceeding ∼15 cm/yr for more than ∼10 Myr should be considered as potential artefacts requiring further justification of plate driving forces in such scenarios.

Subduction-transition zone interaction: A review

“…This indicates that the forcing by downgoing plates older than ~50 m.y. is generally sufficiently large to overcome other forces (e.g., by the upper plate or the convective mantle) that may impede trench motions, consistent with the long-standing conclusion that the downgoing plate pull is the primary force driving plate motions (Forsyth and Uyeda, 1975;Zahirovic et al, 2015). A recent global dynamic modeling study also concluded that subducting plates provide the main forces that drive formation and migration of plate boundaries (Mallard et al, 2016).…”

“…Most Cenozoic downgoing plate motions range between ~5 and 10 cm/yr (Sdrolias and Müller, 2006;Müller et al, 2008;Goes et al, 2011;Zahirovic et al, 2015), and there is a correlation of increasing velocity with the age of the plate at the trench (Carlson et al, 1983;Lallemand et al, 2005;Goes et al, 2011). This range and the age trend have been interpreted as an expression of upper-mantle slab pull as driving force of the plates (Conrad and LithgowBertelloni, 2002;Faccenna et al, 2007;Goes et al, 2011).…”

“…ago (Lee and Lawver, 1995;Müller et al, 2008;Capitanio et al, 2010a). It has been suggested that these fast motions are due to: plate avalanching into the lower mantle (Goes et al, 2008), to the setting up of a whole mantle convection circulation, as opposed to upper-mantle confined cells (Becker and Faccenna, 2011;Faccenna et al, 2013), and for India, the push of the Reunion plume and consequent lowering of asthenospheric viscosities below the plate (Cande and Stegman, 2011;van Hinsbergen et al, 2011), a pull by double subduction (Jagoutz et al, 2015) or the removal of the Indian cratonic keel (Kumar et al, 2007), or the interplay of several of these factors (Zahirovic et al, 2015).…”

Philippine Sea Plate inception, evolution, and consumption with special emphasis on the early stages of Izu-Bonin-Mariana subduction

“…The PSP was the fastest-moving plate during Cenozoic times (Zahirovic et al 2015). Today, the absolute motion of its southern part (∼10 cm/year) in classical reference frames (DeMets et al 2010;Seton et al 2012or Kreemer et al 2014) is comparable to that of the Pacific Plate, which is presently the fastest plate in the world.…”

Neo-Tethys geodynamics and mantle convection: from extension to compression in Africa and a conceptual model for obduction

“…11: Africa absolute velocity (Doubrovine et al 2012;Gaina et al 2013) based on moving hot spots and a true polar wander model before 124 Ma. 12: Africa RMS velocity, hybrid moving hotspots, and true polar wander corrected reference frame (Zahirovic et al 2015). 13: Africa-Eurasia convergence velocity at the longitude of Oman ).…”