Simulating faults and plate boundaries with a transversely isotropic plasticity model

Sharples, Wendy; Moresi, Louis; Velic, Mirko; Jadamec, M. A.; May, David A.

doi:10.1016/j.pepi.2015.11.007

Cited by 14 publications

(11 citation statements)

References 56 publications

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“…Incorporating realistic rheology into 3‐D models of subduction, lithospheric deformation, and mantle convection is still a challenge [ Lev and Hager , ; Koons et al , ; Bercovici and Ricard , ; Bercovici et al , ; Sharples et al , ; Thielmann et al , ; Tommasi and Vauchez , ; Gerya , ; Jadamec , ; Sharples et al , ; Coltice et al , ; Holt and Becker , ]. Models presented in this study do not contain elasticity, but instead represent long‐term viscous flow.…”

Section: Discussionmentioning

confidence: 99%

Tectonic drivers of the Wrangell block: Insights on fore‐arc sliver processes from 3‐D geodynamic models of Alaska

Haynie

Jadamec

2017

Tectonics

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Intracontinental shear zones can play a key role in understanding how plate convergence is manifested in the upper plate in regions of oblique subduction. However, the relative role of the driving forces from the subducting plate and the resisting force from within intracontinental shear zones is not well understood. Results from high‐resolution, geographically referenced, instantaneous 3‐D geodynamic models of flat slab subduction at the oblique convergent margin of Alaska are presented. These models investigate how viscosity and length of the Denali fault intracontinental shear zone as well as coupling along the plate boundary interface modulate motion of the Wrangell block fore‐arc sliver and slip across the Denali fault. Models with a weak Denali fault (1017 Pa s) and strong plate coupling (1021 Pa s) were found to produce the fastest motions of the Wrangell block (∼10 mm/yr). The 3‐D models predict along‐strike variation in motion along the Denali fault, changing from dextral strike‐slip motion in the eastern segment to oblique convergence toward the fault apex. Models further show that the flat slab drives oblique motion of the Wrangell block and contributes to 20% (models with a short fault) and 28% (models with a long fault) of the observed Quaternary slip rates along the Denali fault. The 3‐D models provide insight into the general processes of fore‐arc sliver mechanics and also offer a 3‐D framework for interpreting hazards in regions of flat slab subduction.

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Section: Discussionmentioning

confidence: 99%

Tectonic drivers of the Wrangell block: Insights on fore‐arc sliver processes from 3‐D geodynamic models of Alaska

Haynie

Jadamec

2017

Tectonics

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“…and P is the dynamic pressure and the term τ ij contains the viscosity, η, and the strain-rate tensor,ε ij , and the subscripts, ij , refer to the components of the stress and strain rate tensors (Moresi and Solomatov, 1995;White, 2003). Specific viscosity formulations, such as a strain rate dependent viscosity based on experimentally derived flow laws (Hirth and Kohlstedt, 2003;Billen and Hirth, 2007) or directionally dependent mechanically weakening (Lev and Hager, 2011;Sharples et al, 2016), can be used and connected to the force balance through this equation.…”

Section: Governing Equations For Viscous Flow Modellingmentioning

confidence: 99%

“…Accurately incorporating the upper plate, and the corresponding plate interface, in numerical models of subduction remains a challenge . It is still non-trivial to define a rheological formulation that allows for weakening of the plate boundaries and strengthening of the plate interiors, in such a way that these features emerge from the dynamics and evolve in space and time with the subduction zone forces (Regenauer-Lieb et al, 2001;Kaus and Podladchikov, 2006;Crameri et al, 2012;Bercovici and Ricard, 2014;Sharples et al, 2016).…”

Section: From 2d To 3d Numerical Models Of Subductionmentioning

confidence: 99%

Insights on slab-driven mantle flow from advances in three-dimensional modelling

Jadamec

2016

Journal of Geodynamics

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The wealth of seismic observations collected over the past 20 years has raised intriguing questions about the three-dimensional (3D) nature of the mantle flow field close to subduction zones and provided a valuable constraint for how the plate geometry may influence mantle flow proximal to the slab. In geodynamics, there has been a new direction of subduction zone modelling that has explored the 3D nature of slabdriven mantle flow, motivated in part by the observations from shear wave splitting, but also by the observed variations in slab geometries worldwide. Advances in highperformance computing are now allowing for an unprecedented level of detail to be incorporated into numerical models of subduction. This paper summarizes recent advances from 3D geodynamic models that reveal the complex nature of slab-driven mantle flow, including trench parallel flow, toroidal flow around slab edges, mantle upwelling at lateral slab edges, and small scale convection within the mantle wedge. This implies slab-driven mantle deformation zones occur in the asthenosphere proximal to the slab, wherein the mantle may commonly flow in a different direction and rate than the surface plates, implying laterally variable plate-mantle coupling. The 3D slab-driven mantle flow can explain, in part, the lateral transport of geochemical signatures in subduction zones. In addition, high-resolution geographically referenced models can inform the interpretation of slab structure, where seismic data

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“…In addition, B‐type olivine fabric has a fast axis normal to the direction of flow [ Jung and Karato , ; Kneller et al , ; Jung et al , ; Kneller et al , ; Long and Silver , ], and there can be contributions from the slab or overriding plate [ Levin et al , ; Faccenda et al , ; Hammond et al , ; Song and Kawakatsu , ]. Furthermore, although the models here contained a dynamic reduction in the magnitude of the viscosity due to the strain rate dependence in the olivine flow law [ Hirth and Kohlstedt , ; Billen and Hirth , ; Jadamec , ], the reduction was isotropic; there was no mechanical anisotropy [ Lev and Hager , ; Sharples et al , ] to the viscosity reduction, which could in turn affect the mantle flow patterns and resulting predicted splitting.…”

Section: Discussionmentioning

confidence: 99%

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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Simulating faults and plate boundaries with a transversely isotropic plasticity model

Cited by 14 publications

References 56 publications

Tectonic drivers of the Wrangell block: Insights on fore‐arc sliver processes from 3‐D geodynamic models of Alaska

Tectonic drivers of the Wrangell block: Insights on fore‐arc sliver processes from 3‐D geodynamic models of Alaska

Insights on slab-driven mantle flow from advances in three-dimensional modelling

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

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