Tectonic Subsidence of Qiongdongnan Basin and Its Main Control Factors

Abstract

AbstractBased on the data from 28 boreholes and the latest data of 3 seismic lines, the estimation of tectonic subsidence shows that the Qiongdongnan Basin (QDNB) experienced three episodes of rapid subsiding and one episode of slow subsiding in Cenozoic time. In Eocene and Oligocene to early Miocene time, both the western and eastern QDNB underwent two episodes of rapid subsiding with different subsidence rates. There came a weak subsiding period from 16 Ma to 10.5 Ma in the western QDNB and from 16 Ma to 5.3 Ma in the mid‐eastern QDNB. A rapid subsiding event occurred again at 10.5 Ma in the west and at 5.3 Ma in the mid‐east areas of QDNB. The first rapid subsiding was a result of the combination of extension of the East Asia continental margin and sinistral strike‐slip of the Red River Fault (RRF) in Eocene; the second one was related with the seafloor spreading of the South China Sea (SCS) and sinistral strike‐slip of RRF in Oligocene to early Miocene; the third one is mainly controlled by the dextral strike‐slip of RRF since 10‐5Ma; the weak subsiding process was coeval with the weakly strike‐slipping period of RRF within mid‐late Miocene time and a response to the cease of the seafloor spreading of SCS.