This website requires JavaScript.

Elasto-thermo-visco-plastic numerical modelling from a laboratory to geodynamic scale: implications for convergence-driven experiments

Ekeabino MomohHarsha S. BhatSteve Tait
Dec 2022
The development of a subduction zone, whether spontaneous or induced,encompasses a stage of strain localization and is epitomized by the growth oflithospheric-scale shear bands. Our aim in this paper, using a solid-mechanicalconstitutive description relevant for oceanic lithosphere, is to investigatefactors that promote or inhibit localization of deformation in brittle andductile regimes in convergence-driven numerical experiments. We used theDrucker-Prager yield criterion and a non-associative flow rule, allowingviscoplastic deformation to take directions independent of the preferreddirection of yield. We present a step-by-step description of the constitutivelaw and the consistent algorithmic tangent modulus. The model domain containsan initial weak-zone on which localization can potentially nucleate. In solvingthe energy conservation problem, we incorporate a heat source term from themechanical deformations which embodies the irreversible plastic work done. Thiswork term couples the energy equation to the constitutive description, andhence hence the stress balance, via the evolving temperature field. On asample-scale, we first conduct a series of isothermal benchmark tests. We thenexplore behavior including shear heating and volumetric work both separatelyand in concert. and thereby address the (in)significance of the latter, andhence assess their potential importance. We find that dilatational effectsmostly enhance both shear band development and shear heating. We also observethat high temperature promotes shear band development whereas high confiningpressure inhibits it, and infer that the competition between these factors islikely to be the major influence on the position within the lithosphere whereshear bands nucleate.