珠江口盆地西部珠三坳陷沉降史分析

Analysis of Subsidence History of Zhusan Depression in Western Pearl River Mouth Basin

对珠三坳陷古近系和新近系沉降史进行了回剥分析,指出,珠三坳陷沉降速率演化特征与珠江口盆地的构造演化及坳陷的沉积充填有着密切联系。在渐新世早期,沉降主要受控于构造的活动,珠三坳陷处于断陷期,沉降速率值大,裂谷湖泊充填,是主要烃源岩发育期;渐新世晚期,坳陷进入断拗期,构造活动与裂后整体沉降共同作用,使早期沉降减慢,呈多套砂泥岩沉积,发育区域性储集体;晚期沉降再次加快,以泥质沉积为主,形成较好的区域盖层。

The back-stripping analysis of Tertiary subsidence history in Zhusan depression shows that its subsidence feature is closely related to the structural evolution and depression sedimentation of Pearl River Mouth basin. In the early Oligocene, the subsidence of Zhusan depression was mainly controlled by tectonic movement with big value of subsidence rate and rift filled by the lake, being in stage of fault and source rock development. In the late Oligocene, the depression entered into stage of fault and depression, controlled by tectonic movement and subsidence after rift, slowing the subsidence rate, shaping regional reservoir body with multi-set sand-shale sediments. By the end of Oligocene, the subsidence rate was increased, forming better regional muddy cap rocks in this area.