Fault imprint in clay units: Magnetic fabric, p-wave velocity, structural and mineralogical signatures

摘要: Abstract We investigated the evolution of structure, physical properties and fluid flow across a fault zone within Toarcian shale formation from Tournemire Underground Research Laboratory (France). With this purpose, an integrated approach was used based on analysis petrofabric (anisotropy magnetic susceptibility, AMS, p-wave velocity, APV) mineralogy two cores intercepting F2 fault, strike-slip with small vertical offset. The fracture patterns indicated that registered multiphase tectonic evolution. Two regimes, approximate NE-SW NW-SE compression, normal regime WNW-ESE direction extension were identified. Most N-S planes collected in TF1 core, have shallow dip values between 5° to 45°. further evidenced close relationship architecture petrophysical properties. A preferential orientation K1 axes observed is agreement extensional dextral movement fault. Within important decrease anisotropy indicates clay platelets rotations related deformation. weaker anisotropic change ASM1. This difference may be local variability suggests need study characteristics both its different architectural zones along main plan. Finally, we identified evidence minerals alteration reactivation circulation. Fluid circulation enabled transformation siderite magnetite, neo-formation kaolinite precipitation calcite at vicinity damage zone/fault core boundary. In TF1, while major mineralogical changes occur zone. ASM1, higher illite-smectite mixed layers content eastern side