A Review of the Role of Subduction Dynamics for Regional and Global Plate Motions

Becker, T. W.; Faccenna, Claudio

doi:10.1007/978-3-540-87974-9_1

Cited by 50 publications

(75 citation statements)

References 212 publications

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“…The results imply that the zone of influence is larger during the process of slab steepening and retrograde slab motion. The general sense of mantle flow during these subduction stages has been shown previously in buoyancy‐driven models [ Garfunkel et al , ; Funiciello et al , ; Schellart , ; Funiciello et al , ; Becker and Faccenna , ; Strak and Schellart , ]. This illustrates the marked difference in the flow fields predicted by buoyancy‐driven subduction models versus corner flow models, and why a corner flow model would not have a zone of influence extending beneath the slab.…”

Section: Discussionsupporting

confidence: 73%

The zone of influence of the subducting slab in the asthenospheric mantle

2017

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Due to the multidisciplinary nature of combined geodynamics and shear wave splitting studies, there is still much to be understood in terms of isolating the contributions from mantle dynamics to the shear wave splitting signal, even in a two‐dimensional (2‐D) mantle flow framework. This paper investigates the viscous flow, lattice preferred orientation (LPO) development, and predicted shear wave splitting for a suite of buoyancy‐driven subduction models using a non‐linear rheology to shed light on the nature of the slab‐driven asthenospheric flow and plate‐mantle coupling. The slab‐driven zone of influence in the mantle, LPO fabric, and resulting synthetic splitting are sensitive to slab strength and slab initial slab dip. The non‐linear viscosity formulations leads to dynamic reductions in asthenospheric viscosity extending over 600 km into the mantle wedge and over 300 km behind the trench, with peak flow velocities occurring in models with a weaker slab and moderate slab dip. The olivine LPO fabric in the asthenosphere generally increases in alignment strength with increased proximity to the slab but can be transient and spatially variable on small length scales. The results suggest that LPO formed during initial subduction may persist into the steady state subduction regime. Vertical flow fields in the asthenosphere can produce shear wave splitting variations with back azimuth that deviate from the predictions of uniform trench‐normal anisotropy, a result that bears on the interpretation of complexity in shear wave splitting observed in real subduction zones. Furthermore, the models demonstrate the corner flow paradigm should not be equated with a 2‐D subduction framework.

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Section: Discussionsupporting

confidence: 73%

The zone of influence of the subducting slab in the asthenospheric mantle

2017

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“…Treating the system as one with varying degrees of rheological sophistication reproduces plate motions well at the global level (LithgowBertelloni & Richards 1998;Becker & Faccenna 2009;Gosh & Holt 2012;van Summeren et al 2012) and even at the regional level of smaller plates or regions where the plate boundary rheology becomes significant (Stadler et al 2010).…”

Section: Driving Forces Of Riftingmentioning

confidence: 97%

Why is Africa rifting?

Kendall

Lithgow‐Bertelloni

2016

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Continental rifting has a fundamental role in the tectonic behaviour of the Earth, shaping the surface we live on. Although there is not yet a consensus about the dominant mechanism for rifting, there is a general agreement that the stresses required to rift the continental lithosphere are not readily available. Here we use a global finite element model of the lithosphere to calculate the stresses acting on Africa. We consider the stresses induced by mantle flow, crustal structure and topography in two types of models: one in which flow is exclusively driven by the subducting slabs and one in which it is derived from a shear wave tomographic model. The latter predicts much larger stresses and a more realistic dynamic topography. It is therefore clear that the mantle structure beneath Africa plays a key part in providing the radial and horizontal tractions, dynamic topography and gravitational potential energy necessary for rifting. Nevertheless, the total available stress (c. 100 MPa) is much less than that needed to break thick, cold continental lithosphere. Instead, we appeal to a model of magma-assisted rifting along pre-existing weaknesses, where the strain is localized in a narrow axial region and the strength of the plate is reduced significantly. Mounting geological and geophysical observations support such a model. Gold Open Access:This article is published under the terms of the CC-BY 3.0 license.

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“…Fully three‐dimensional numerical models, while computationally expensive, have the advantage of being able to explore the possibility of 3‐D flow patterns in subduction systems. The possibility of toroidal flow around subducting slabs associated with retreating trenches has been investigated by many 3‐D numerical modeling studies [e.g., Stegman et al ., ; Piromallo et al ., ; Schellart et al ., ; Becker and Faccenna , ; Faccenda and Capitanio , , ] and a subset of these have directly addressed the anisotropic signature that likely results from such flow. For example, Becker and Faccenna [] explored the implications of a dynamic subduction model from Becker and Faccenna [2010] for mantle flow and anisotropy beneath subducting slabs, highlighting the strong component of trench‐parallel flow beneath a retreating slab.…”

Section: Geodynamical Modeling Constraintsmentioning

confidence: 99%

“…The possibility of toroidal flow around subducting slabs associated with retreating trenches has been investigated by many 3‐D numerical modeling studies [e.g., Stegman et al ., ; Piromallo et al ., ; Schellart et al ., ; Becker and Faccenna , ; Faccenda and Capitanio , , ] and a subset of these have directly addressed the anisotropic signature that likely results from such flow. For example, Becker and Faccenna [] explored the implications of a dynamic subduction model from Becker and Faccenna [2010] for mantle flow and anisotropy beneath subducting slabs, highlighting the strong component of trench‐parallel flow beneath a retreating slab. A more recent modeling study by Faccenda and Capitanio [] (Figure ) predicted finite strain and SKS splitting behavior for a fully dynamic retreating slab model; this study found that toroidal flow at a slab edge induces a deep layer of strong trench‐parallel strain beneath a layer of entrained flow plate‐motion‐parallel strain immediately beneath the slab.…”

Section: Geodynamical Modeling Constraintsmentioning

confidence: 99%

Constraints on Subduction Geodynamics From Seismic Anisotropy

Long

2013

Reviews of Geophysics

188

234

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[1] Much progress has been made over the past several decades in delineating the structure of subducting slabs, but several key aspects of their dynamics remain poorly constrained. Major unsolved problems in subduction geodynamics include those related to mantle wedge viscosity and rheology, slab hydration and dehydration, mechanical coupling between slabs and the ambient mantle, the geometry of mantle flow above and beneath slabs, and the interactions between slabs and deep discontinuities such as the core-mantle boundary. Observations of seismic anisotropy can provide relatively direct constraints on mantle dynamics because of the link between deformation and the resulting anisotropy: when mantle rocks are deformed, a preferred orientation of individual mineral crystals or materials such as partial melt often develops, resulting in the directional dependence of seismic wave speeds. Measurements of seismic anisotropy thus represent a powerful tool for probing mantle dynamics in subduction systems. Here I review the observational constraints on seismic anisotropy in subduction zones and discuss how seismic data can place constraints on wedge, slab, and sub-slab anisotropy. I also discuss constraints from mineral physics investigations and geodynamical modeling studies and how they inform our interpretation of observations. I evaluate different models in light of constraints from seismology, geodynamics, and mineral physics. Finally, I discuss some of the major unsolved problems related to the dynamics of subduction systems and how ongoing and future work on the characterization and interpretation of seismic anisotropy can lead to progress, particularly in frontier areas such as understanding slab dynamics in the deep mantle.

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A Review of the Role of Subduction Dynamics for Regional and Global Plate Motions

Cited by 50 publications

References 212 publications

The zone of influence of the subducting slab in the asthenospheric mantle

The zone of influence of the subducting slab in the asthenospheric mantle

Why is Africa rifting?

Constraints on Subduction Geodynamics From Seismic Anisotropy

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