Genesis and evolution of the structural systems during the cenozoic in the Sanjiang orogenic belt, Southwest China

The southwest Sanjiang structural systems in the Sanjiang orogenic bett, Southwest China is characterized by asymmetric strike-slip thrust with the Changdu Lanping Simao block as the central axis, the extensional detachment structure and the strike-slip-pull-apart basin system accompanied by strike slip faults, and the near NE-and NW-trending strike slip fault systems within the blocks. The evolution of the tectonic system of the orogenic belt in Southwest China can be divided into compression and contraction deformation stage, strike slipping, deep melting and thermal uplift stage, strike slip shear extension stage and strike slip denudation uplift stage. In the Late Cretaceous, the collision between the Indian plate and the Eurasian plate resulted in the initial formation of the thrust system in the southwest Sanjiang orogenic belt. Since the Oligocene, the Indian plate has been continuing to wedge into the Eurasian continent northward. The Indian plate and the Yangtze craton have formed a couple of forces. They moved in opposite and relative directions. They compressed and sheared the Tethys oceanic suture zone and the arc basin system of the two continental margins. While the southwest Sanjiang orogenic belt developed further, the nearly north-south shear strike slip system was formed, and the tectonic direction also changed from near east-west to near north-south. The extensional detachment structures and pull apart basins, which are accompanied by nearly N-S strike slip fault zone, are formed by shear strike slip faults which of near NE and NW directions. In this way, a large-scale structural system of thrust faults, strike slip faults, rotations and their associated extensional and pull apart basins has formed in the southwest Sanjiang orogenic belt.