Nonlinear viscoplasticity in ASPECT: benchmarking and applications to subduction

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.

Improving subduction interface implementation in dynamic numerical models

“…This approach was first applied as a spatially fixed low-viscosity zone that could decouple the plates but would not allow trench motion (e.g. Gurnis and Hager, 1988). This type of implementation was developed so that narrow low-strength weak zone "stencils" could also be advected to allow trench motion (Kincaid and Sacks, 1997;Billen and Hirth, 2007).…”

“…Over the past decade the use of an entrained weak layer (WL) has become an increasingly common strategy (e.g. Babeyko and Sobolev, 2008;Capitanio et al, 2010;Magni et al, 2012;Chertova et al, 2012;Čížková and Bina, 2013;Garel et al, 2014;Holt et al, 2015;Agrusta et al, 2017;Glerum et al, 2018;Arredondo and Billen, 2017). Rather than using a fixed weak zone, the subduction interface is typically implemented by imposing a material layer at the top of the subducting plate that is advected with the flow and continuously entrained into the decoupling region.…”

Aborted propagation of the Ethiopian rift caused by linkage with the Kenyan rift

“…It also features a larger model domain of 1200×600×165 km and a higher resolution of up to 2.5 km, which allows for more detailed analysis of local extension direction during rift localisation in previous models 17 . The governing physical equations are solved using the geodynamic modelling software ASPECT [33][34][35][36][37] . A detailed description of thermal and rheological configurations, mesh refinement strategy as well as initial and boundary conditions can be found in the Methods section.…”

“…6a means that 20 out of a total of 25 steps were included). The step-heating age spectra are plotted along with the evolved 37 Ar Ca , 38 Ar Cl and 36 Ar atm normalised to 39 Ar K ( 39 Ar produced from 39 K during irradiation). Tabulated age errors are ±2σ.…”

Multidimensional Geodynamic Modeling in the Southeast Carpathians: Upper Mantle Flow‐Induced Surface Topography Anomalies

“…(c) The background temperature field for 3-D (red line; Demetrescu & Andreescu, 1994) and 2-D numerical experiments (blue curve; e.g., Shaw & Pysklywec, 2007;Uluocak et al, 2016). the plastic yield parameters are given in Table 1. The effective viscosity (η e ) in the viscous stress is defined for the power law creep based on the temperature and the strain rate tensor (_ ε; e.g., Glerum et al, 2018;Karato, 2008):…”