Metamorphic rocks affected by a fault have undergone chemical, mineralogical, and textural changes. The most significant is the enrichment in clay minerals (chlorite, kaolinite, and smectite). Geothermometry of the new chlorites made it possible to determine the temperatures of the processes (predominantly < 225°C), promoted by the fault dynamics (mainly fluid-related alterations). The retrograde alteration also affected the fluid-accessible zones of the original rocks, with growth of the same clay minerals.