Rock Magnetic Responses to Creep and Stick‐Slip Deformation Processes in the Xianshuihe Fault Zone, Eastern Tibetan Plateau

Abstract The Xianshuihe fault zone (XSHF) in southwestern China accommodates both aseismic creep and seismic slip, yet geological evidence constraining these processes remains limited. Hence, we conducted microstructural, geochemical, and rock magnetic analyses of fault‐zone materials from the Cuoniulongba River outcrop. Fault breccias and relatively undeformed sandstones adjacent to the principal slip zone (PSZ) exhibit elevated magnetic susceptibility (MS), likely reflecting monoclinic pyrrhotite precipitated from post‐seismic low‐temperature hydrothermal fluids. Creep‐related fault gouge within the PSZ is characterized by low MS. Notably, the gouge sample S4 within the PSZ shows high MS, reflecting magnetite neoformation induced by coseismic frictional heating (>500°C), consistent with the observation of thermal decomposed kaolinite due to fluid drainage. This study presents the geological evidence associated with the XSHF linked to aseismic creep, coseismic frictional heating, and post‐seismic hydrothermal alteration, and provides new insights into the seismic behavior of continental strike‐slip faults.