CC-SS - coupled crack-seal simulation

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Syntaxial crack-seal veins are first order structures in deep, hydrothermal and reactive (THMC) environments where fluids create and moderate permeability and reactions interact with deformation. In recent work, we successfully modelled these veins using two different approaches: we used the Phase Field Method (PFM) to model epitaxial growth of Quartz from an aqueous solution, based on thermodynamic and kinetic principles but with simplified assumptions on crack geometry; in another study we used the Discrete Element Method (DEM) to model the growth of crack-seal veins in 3D, based on mechanical principles but with simplified assumptions on crystal growth. Here we propose to couple these two methods, to study the coupled thermal, hydraulic, mechanical and chemical evolution of syntaxial crack-seal veins in bi-directionally coupled PFM and DEM models. For this we will develop exchange routines to translate the spatial domains of DEM to PFM and vice versa, to model the fracturing process with DEM and the sealing processes with PFM. Observations of syntaxial vein microstructures will provide data on microstructure, vein crystal morphology and facet crystallography for comparison of our results with natural prototypes. The coupled models will lead to a better understanding of the feedback mechanisms between fracturing and sealing processes, quantify the evolution of mechanical and transport processes, help define new diagnostic microstructures in natural veins and form the basis for upscaling our models. A parametric study of syntaxial quartz and calcite veins will test hypotheses on (i) evolution of vein microstructure, (ii) rate of opening versus rate of crystal growth, (iii) relative strength of vein cement and host rock, and of the (iv) connectivity of vein porosity and evolution of permeability in hydrothermal, syntaxial crack-seal veins.