摘要

In three shallow-level fault systems in eastern China, nano-sized (30-100 nm) grinding grain textures are found in the thin-shelled rheological layer representing frictional-viscous high strain field. The surface layer near slipping plane is composed of stacks of grinding grains with high sphericity and uniform nano-sized diameter, while the underlying layer appears as a mixture of irregular ones with diverse diameters. Rock deformation experiments indicate that the grinding grain texture is a common phenomenon in shearing fractures, suggesting a potential transition from sliding friction to rolling one during the rock deformation process. This transition is crucial for many tribological processes in geological fields.