Petrogenesis of anatectic leucogranites: Constraints on the tectonic evolution of the Ailao Shan–Red River shear zone, southeastern Tibetan Plateau

The Ailao Shan–Red River (ASRR) shear zone, which hosts abundant leucogranites and migmatites, plays an important role in accommodating the southeastward extrusion of the Indochina Block and releasing compressional stress generated by the collision between the Indian and Eurasian plates. These processes provide crucial insights into the temperature and pressure conditions associated with regional dynamic mechanisms. In this study, we present results from investigations of leucogranites and metapelitic migmatites within the ASRR shear zone to elucidate the generation mechanisms of leucogranites and to constrain the relationship between anatexis and strike-slip movement of the ASRR shear zone. Our results demonstrate that the leucogranites were generated by muscovite and biotite dehydration melting of metapelitic migmatites during the prograde to peak metamorphic stage. In combination with previous studies, we propose that the ASRR shear zone underwent two stages of anatexis. This process reduced rock strength and changed crustal rheological properties. Consequently, the shear zone acted as a “conduit” for leucogranite formation at higher crustal levels.