Numerical modeling of compositionally driven convection in a reactive porous layer

A reactive porous medium is one in which an interstitial fluid may exchange mass through melting and freezing with a solid matrix. In a multi-component system, fractionation may occur which can have a significant impact on the density of the interstitial fluid which can, in turn, lead to compositionally driven convection within the porous layer. These convective motions can lead to significant variations in the spatial distribution of porosity and bulk composition. Analogue experiments for such geological systems as melting in the upper mantle and magma chamber dynamics have been carried out using various aqueous salt solutions. In this contribution, we present a numerical model for compositional convection in a reactive porous layer. We first scale the model to be similar to an analogue experiment using an aqueous NH4 solution and we will show that the results of the experiments and simulations are quite similar. We present results indicating the effects of the various control parameters of the simulations on the final distribution of porosity and bulk solute concentration. Ramifications of our results for deep Earth systems will then be discussed.