Preprints
https://doi.org/10.5194/egusphere-2024-3504
https://doi.org/10.5194/egusphere-2024-3504
05 Dec 2024
 | 05 Dec 2024

Models of buoyancy-driven dykes using continuum plasticity and fracture mechanics: a comparison

Yuan Li, Timothy Davis, Adina E. Pusok, and Richard F. Katz

Abstract. Magmatic dykes are thought to play an important role in the thermomechanics of tectonic rifting of the lithosphere. Our understanding of this role is limited by the lack of models that consistently capture the interaction between magmatism, including dyking, and tectonic deformation. While linear elastic fracture mechanics (LEFM) has provided a basis for understanding the mechanics of dykes, it is difficult to consistently incorporate LEFM into geodynamic models. Here we further develop a continuum theory that represents dykes as plastic tensile failure in a two-phase, Stokes–Darcy model with a poro- viscoelastic–viscoplastic (poro-VEVP) rheological law (Li et al., 2023). We validate this approach by making quantitative comparison with LEFM, enabled by a novel poro-LEFM formulation. The comparison shows that dykes in our continuum theory propagate slowly—a consequence of Darcian drag on the magma. Moreover, dissipation of mechanical energy in the poro-VEVP model implies a high critical stress intensity in LEFM. We improve the poro-VEVP model by reformulating the compaction stress and incorporating anisotropic permeability in regions of plastic failure.

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Short summary
Magmatic dykes transport magma to the Earth's surface, sometimes causing eruptions. We advanced...
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