Evidence of phyllosilicate alteration processes and clay mineral neoformation promoted by hydrothermal fluids in the Padul Fault area (Betic Cordillera, SE Spain)

Geochemical changes and authigenic clays were detected in the fault rocks of Padul Fault. An enrichment from protolith to ultracataclasites Si, Al, Fe, Ca, Ti also Zn but an impoverishment Mg was detected. Although (dolostones) are mostly composed carbonates, characterized by presence fine-grained matrix (mainly chlorite Mg-rich biotite, smectite punctually talc). Neither nor talc protolith. The application thermometry gives temperatures around 140–220 °C for chlorites lamellae located on plane. These compositionally homogeneous, whereas cataclasites more variable, although both them have almost no Fe. As well, usually include their composition and, as observed at nanoscale, they genetically related biotites, which come Talc grains (< 1 μm) always found between dolomite calcite. observations point clay mineral reactions precipitation promoted circulation fault-controlled hydrothermal fluids close 200 °C. Other such result final step activity fault. identification minerals, cause weakening mechanisms, is consistent with geodetic characterization Fault, plays important role aseismic deformation.