Study of the Quaternary Activities of the Red River Fault (I) - General Survey of its Contemporary Activities and Evidence of the Active Faulting

Abstract

The Red River fault is one of the major regional faultings in China. Its southern segment shows spectacular linear structures characterized by features of clear-cut strike-slip faultings. Contemporary activities have primarily right lateral features along the segment of the fault, which is approximately 500 km in length, extending southeastward from Fengyi, Yunnan to the Sino-Vietnamese border. From Chunyuan, southeast of Ejia, the southern segment of the Red River fault actually diverges into 2 branches, one of which is the principal faulting running closely to the Ailao Mountain metamorphic zone, the other is developed in the young deposits northeast of the former branch. The former branch had considerably strong vertical differential movement at the beginning of the Cenozoic era, and is now dominated by tilting movement. The latter branch is principally controlled by right lateral strike-slip movements and is the most active branch in the contemporary times.