南海西南部曾母盆地早中新世以来沉降史分析

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

采用回剥法和局部均衡模式研究曾母盆地早中新世以来的沉降史,并探讨了该盆地构造演化特征。曾母盆地自早中新世以来经历了17.5～11.6Ma、11.6～5.5Ma、5.5～3.0Ma和3.0～0Ma的4次快速沉降作用,其构造演化受控于曾母地块与南沙地块及婆罗洲地块的碰撞和盆地两侧的万安—卢帕尔断裂与廷贾走滑断裂的综合作用,可划分为南北双向挤压(晚始新世—早中新世)、走滑改造(中中新世—晚中新世)和区域沉降(上新世—第四纪)3个演化阶段。

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-Quatemary）.