Lasting mantle scars lead to perennial plate tectonics.

Philip J Heron,Russell N Pysklywec,Randell Stephenson

doi:10.1038/ncomms11834

Philip J Heron, Russell N Pysklywec + Show 1 more

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https://doi.org/10.1038/ncomms11834

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Abstract

Mid-ocean ridges, transform faults, subduction and continental collisions form the conventional theory of plate tectonics to explain non-rigid behaviour at plate boundaries. However, the theory does not explain directly the processes involved in intraplate deformation and seismicity. Recently, damage structures in the lithosphere have been linked to the origin of plate tectonics. Despite seismological imaging suggesting that inherited mantle lithosphere heterogeneities are ubiquitous, their plate tectonic role is rarely considered. Here we show that deep lithospheric anomalies can dominate shallow geological features in activating tectonics in plate interiors. In numerical experiments, we found that structures frozen into the mantle lithosphere through plate tectonic processes can behave as quasi-plate boundaries reactivated under far-field compressional forcing. Intraplate locations where proto-lithospheric plates have been scarred by earlier suturing could be regions where latent plate boundaries remain, and where plate tectonics processes are expressed as a ‘perennial' phenomenon.

Highlights

Mid-ocean ridges, transform faults, subduction and continental collisions form the conventional theory of plate tectonics to explain non-rigid behaviour at plate boundaries
As deep seismic reflector anomalies are generally inferred to represent deformation relating to ancient tectonic margin processes, these mantle lithosphere (ML) scars can be classified as weak zones via the continuum theory of damage mechanics[8,12]
The upper crust (UC) fault reactivation produces folding in the UC, but acts to thicken the lower crust (LC) and produce subcrustal subduction within the ML

Summary

Introduction

Mid-ocean ridges, transform faults, subduction and continental collisions form the conventional theory of plate tectonics to explain non-rigid behaviour at plate boundaries. Seismic reflection data from Canada, the Alps, the Pyrenees, the North Sea, and the Skagerrak and Hebrides shelf have identified tectonic structures as scarred lithosphere extending deep into Earth’s interior[1,2,3] (yellow crosses, Fig. 1) Such seismic reflectors in the mantle lithosphere (ML) have been interpreted to be related to relict subduction zones linked to the closing of oceanic basins (that is, ‘subduction scars’ generated at an ancient plate boundary) (for example, refs 4–6). As deep seismic reflector anomalies are generally inferred to represent deformation relating to ancient tectonic margin processes (for example, refs 4,11), these ML scars can be classified as weak zones (that is, a region of reduced grain size at mid-lithospheric depth) via the continuum theory of damage mechanics[8,12]. Geometry (over three-dimensional) so that the experiments track the evolution of fault zones in the crust–mantle tectonic models to high resolution (1-km vertical resolution in the crust)

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