This work reveals the transitions between nanomechanical and continuum contact behaviours at wet quartz interfaces, providing new ways to quantify the liquid structure of interfacial water to study the origin of nanomechanical contact behaviour.

Stress-induced mineral dissolution at contacts is a critical geophysical process in a broad spectrum of phenomena such as earthquake slip weakening, petroleum migration, and rock deformation. However, there is limited understanding of how this geophysical process originates from the grain-to-grain contacts on a nanoscale. In this study, we simulated the contact process of two quartz asperities in water and present a specially designed molecular dynamics (MD)-based scheme to quantify the dissolution tendency at contacts. Our results suggest that a water layer between the two asperities persists even when the quartz crystals are highly deformed. The MD simulation allowed us to evaluate the thermodynamic activity of the formation of silica species in the solution near the quartz surface. Different from the fact that minerals dissolve significantly at contacts, the finding indicates that only a small region of the contact area adjacent to the center of contacts dissolves first.

We investigated the dynamic formation process of capillary bridges and visualised the distribution of water molecules in the capillary bridges.