3D Structure of Clay Smears: Implications for Fault Seals

The geometry and three dimensional structure of more than a dozen clay smears that were formed within a decimetre-scale fault zones by hydromechanical shear experiments were investigated. Different distribution patterns of clay smears are observed in the fault zones as clay composition and consolidation stress of smearing clay layer and fault normal stress during the deformation varied. These variations in smear structures are captured by mapping the clay distributions and building computer-based 3D geo-models. The geometry of smear structures is revealed in detail and different geometries are linked to varying rheology and stress conditions. Volumetric calculations of the fault zone clay contents were carried out and compared to the predictions of fault seal algorithms to test their predictive performance.