A More Responsive M: Dike Injection via Diffuse Yielding in 2–D Rift Models

Magmatic accommodation of extension is often simulated by imposing a divergence term in the continuity equation in a column of model elements. The ratio of the imposed divergence to total extension is the magmatic fraction of spreading, M. To date, most numerical geodynamic models impose a uniform M value through the domain and evaluate tectonic responses to different M values. Imposed uniform M values do not permit magmatic responses to changing lithosphere stresses, topography, and fault evolution. We present a computationally-inexpensive diffuse yielding formulation for M that responds to changing stresses, while still allowing for controlled variations in magmatic overpressure and supply.