Analysis of the subsidence history of the Zengmu basin in the southwest South China Sea since the early Miocene

Abstract：The subsidence history of the Zengmu basin since the early Miocene is studied by the backstripping technique with Airy isostatic correction and the characteristics of the tectonic evolution of the basin are discussed in the paper. The Zengmu basin underwent four periods of rapid subsidence since the early Miocene; they are 17.5-11.6 Ma, 11.6-5.5 Ma, 5.5-3.0 Ma and 3.0-0 Ma. The tectonic evolution of the basin was controlled by combined actions of the collision of the Zengmu block with the Nansha block and Borneo block and the Wa′an-Lupar fault and Tindja strike-slip fault on its both sides. Three evolutionary stages may be distinguished, i.e.：bi-directional N-S compression (late Eocene-early Miocene), strike-slip modification (middle Miocene-late Miocene) and regional subsidence (Pliocene-Quaternary).