Incomplete Crack Sealing Causes Localization of Fracturing in Hydrothermal Quartz Veins
Michael Späth, János L. Urai, Britta Nestler
Abstract
Abstract Cyclic microfracturing and epitaxial crystal growth have long been recognized in crack‐seal veins, but an understanding of a single crack‐seal cycle is still missing. Here we present a phase‐field model that includes both fracture mechanics of crack propagation, and epitaxial crystal growth on the fracture walls, repeating this cycle multiple times in a polycrystalline, microporous quartz rock. Our simulations have two end members: If a vein completely seals, it is stronger than the host rock, cracking is delocalized, forming many single‐seal microveins. Incomplete sealing makes the vein weaker than the host rock and localizes the new fracture inside the vein, leading to multi‐crack‐seal. We suggest that the sealing degree is a key parameter in hydrothermal systems and multi‐crack‐seal veins are long‐lived, microporous sites of mechanical weakness. We generalize the phase‐field approach to conduct probabilistic simulations in between these two types, and show how systems of microveins and multi‐crack‐seal veins emerge.