Publication Date:
2015-03-31
Description:
Recent advances in numerical modelling allow global models of mantle convection to more realistically reproduce the behaviour at convergent plate boundaries; in particular, the inclusion of a free surface at the outer boundary has been shown to facilitate self-consistent development of single-sided subduction. This allows for a more extensive study of subduction in the context of global mantle convection, as opposed to commonly-used regional models. Our first study already indicated important differences between mantle convection with single-sided subduction and mantle convection with double-sided subduction. Here, we further investigate the effect of various physical parameters and complexities on inducing Earth-like plate tectonics and its evolution in time. Results reinforce the previous finding that using a free surface instead of a free-slip outer boundary dramatically changes subduction style, with free surface cases displaying many episodes of single-sided subduction, which leads to more realistic slab dip, stress state, trench retreat rate and slab-induced mantle flow. Longevity of single-sided subduction is promoted by a layer of hydrated crust with a low yield strength to lubricate the subduction channel, a low-viscosity asthenosphere, and a high strength of the slab (determined by a combination of high diffusion-creep viscosity and intermediate friction coefficient), although its effective viscosity is in the observationally-constrained range in the bending region. The time-evolution displays interesting events including subduction polarity reversals, subduction shut-off and slab break-off.
Print ISSN:
0148-0227
Topics:
Geosciences
,
Physics
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