Abstract
Abstract. ASPECT (Advanced Solver for Problems in Earth's ConvecTion) is a massively parallel finite element code originally designed for modeling thermal convection in the mantle with a Newtonian rheology. The code is characterized by modern numerical methods, high-performance parallelism and extensibility. This last characteristic is illustrated in this work: we have extended the use of ASPECT from global thermal convection modeling to upper-mantle-scale applications of subduction.Subduction modeling generally requires the tracking of multiple materials with different properties and with nonlinear viscous and viscoplastic rheologies. To this end, we implemented a frictional plasticity criterion that is combined with a viscous diffusion and dislocation creep rheology. Because ASPECT uses compositional fields to represent different materials, all material parameters are made dependent on a user-specified number of fields.The goal of this paper is primarily to describe and verify our implementations of complex, multi-material rheology by reproducing the results of four well-known two-dimensional benchmarks: the indentor benchmark, the brick experiment, the sandbox experiment and the slab detachment benchmark. Furthermore, we aim to provide hands-on examples for prospective users by demonstrating the use of multi-material viscoplasticity with three-dimensional, thermomechanical models of oceanic subduction, putting ASPECT on the map as a community code for high-resolution, nonlinear rheology subduction modeling.
Highlights
Earth is a complex dynamic system that deforms on a wide range of spatial and temporal scales
The shear band angles to the right of the velocity discontinuity of 62 and 60◦ after 1 and 2 cm of deformation fall just outside the ranges found by Buiter et al (2006) and Thieulot (2011) of 45–55 and 45–53◦, respectively, they lie within the theoretical Arthur–Coulomb angles of 54–63◦ for a friction angle of 36◦ (Vermeer, 1990; see Sect. 3.2)
This allows for decoupling from the surface, mechanical coupling is strong enough for the overriding plate (OP) to move towards the trench
Summary
Earth is a complex dynamic system that deforms on a wide range of spatial and temporal scales. We are concerned with the longer geological timescales of the subduction of lithospheric plates into the mantle. On such timescales, rock deformation is mostly nonelastic and characterized by unrecoverable solid-state creep and brittle-plastic failure (Ranalli, 1995; Karato, 2008; Burov, 2011). Strain-rate-dependent viscous deformation through the mechanism of solid-state creep is dominated by linear (Newtonian) diffusion creep and various forms of nonlinear high- and low-temperature dislocation creep (e.g., Ranalli, 1995; Burov, 2011). Plastic yielding occurs when large differential stresses cause rocks to fail beyond the creep regime by local brittle fracture or, at higher temperatures, through ductile homogeneous material flow (Ranalli, 1995; Karato, 2008)
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