- 1Collaborative- Innovation Centre for Exploration of Strategic Mineral Resources, School of Earth Resources, China University of Geosciences, Wuhan, China
- 2School of Earth Sciences, China University of Geosciences, Wuhan, China
- 3Department of Environment and Biodiversity, University of Salzburg, Salzburg, Austria
Metamorphic complexes preserve well-recorded evidence of multistage deformation, metamorphism, magmatism, and fluid-rock interactions. However, the structural relationships between microstructurally constrained ductile deformation and later brittle fault kinematics and stress fields remain insufficiently constrained. The Yuanmou Complex, located in the central–southern Kangdian region along the southwestern margin of the Yangtze Block, China, provides an ideal site to address these issues. In this study, we combine field investigations with optical microscopy–cathodoluminescence (OM–CL), electron backscatter diffraction (EBSD) and paleostress inversion of fault-slip data to investigate the deformation process and stress fields of later brittle faulting in the Yuanmou Complex.
Microstructures and EBSD fabric results indicate that the Yuanmou Complex experienced multistage deformation, evolving from early high-temperature ductile deformation to low-temperature ductile deformation, followed by brittle deformation during exhumation to shallow crustal levels. EBSD fabric analyses of deformed quartz reveal a systematic transition in dominant slip systems, from high-temperature prism slip (>650 °C), through intermediate–high temperature prism
Paleostress inversion reveals the coexistence of compressional, extensional and strike-slip stress regimes. An early stress regime dominated by NNE–SSW-oriented compression is identified, whereas a later stage is characterized by a NW–NWW-oriented principal stress field, under which fault kinematics gradually evolved from thrusting to strike-slip–dominated deformation, accompanied by local extensional activity. Linking ductile deformation processes with subsequent brittle fault kinematics and stress fields, our results reveal their structural connection and reflect regional Cenozoic responses to eastward extrusion of the Tibetan Plateau and southeastward escape of the Sichuan-Yunnan rhombic block.
How to cite: Cheng, X., Cao, S., Jiang, S., and von Hagke, C.: Multiphase deformation and stress field evolution of the Yuanmou metamorphic complex, SW China, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-9871, https://doi.org/10.5194/egusphere-egu26-9871, 2026.
