珠江口盆地深水区新生代构造沉积演化

Cenozoic tectonic and sedimentary evolution of deepwater area,Pearl River Mouth Basin

运用平衡剖面技术对珠江口盆地深水区珠二坳陷的典型测线进行构造演化史恢复,计算不同构造时期的拉张速率及沉积速率等参数,总结其构造沉积演化特征。结果表明：珠二坳陷的构造演化过程可以分为裂陷期和拗陷期两个发育阶段;23 M a之前为裂陷期,伸展作用十分强烈,主要断裂构造发育;23 M a后为裂后的拗陷期,伸展作用减弱;坳陷新生代拉张系数为1.15-1.35,不同凹陷在拉张作用、沉积速率和断裂发育方面具有明显的差异;白云凹陷裂陷期发育陆相断陷湖相和水下三角洲沉积,拗陷期发育深水扇和深海沉积序列。

Balanced cross-section technique was applied to restore tectonic evolution history of the representative seismic lines in the deepwater area of Zhuer depression, Pearl River Mouth Basin. The extensional rate and deposition rate were calculated to discuss the tectonic and sedimentary evolution. The results show that the structural evolution of Zhuer depression could be generally divided into two stages of syn-rift and post-rift. The syn-rift stage is before 23 Ma, when extension and fractrue were strong, and the major faults developed well. The post-rift stage is after 23 Ma, when the extension was weaking. The total stretching factor of the depression is between 1.15 and 1.35. There are obvious difference in the exten- sion, deposition rate and fault development among the different sags. The Baiyun sag developed the syn-rift sequence of lacustrine deposits and submerged delta, followed by the post-rift sequence of deepwater fans and pelagic deposits.