Sedimentary evolution and controls in paleo-Hanjiang delta from 32 to 10.5 Ma

The paleo-Hanjiang delta has become a focus of petroleum exploration in the South China Sea. The sedimentary evolution analysis of the paleo-Hanjiang delta is helpful to evaluate the potential of petroleum resources in the Pearl River Mouth Basin and predict favorable exploration blocks. The sedimentary facies types and evolution of the paleo-Hanjiang delta in the Lufeng-Hanjiang sags from 32-10.5 Ma were analyzed based on core, logging, drilling and seismic data. The results show that paleo-Hanjiang delta can be subdivided into delta plain, delta front and pre-delta in the Hanjiang-Lufeng sags. The evolution of the paleo-Hanjiang delta has experienced three stages. In the first stage, during the sedimentary period from the Zhuhai Formation to the Zhujiang Formation, the sediments of the paleo-Hanjiang delta were coarse in grain size and extended in the delta, mainly distributed in the Lufeng Sag. In the second stage, during deposition of the lower part of Hanjiang Formation, the paleo-Hanjiang delta gradually had reduced provenance in response to increasing sea level. Shallow shelf and carbonate platform were dominant in the Lufeng and Hanjiang area. The sea level reached its maximum in the lower section of the Hanjiang Formation, and the area of the paleo-Hanjiang delta reached its smallest. In the third stage, during the sedimentary period of the upper section of Hanjiang Formation, the paleo-Hanjiang delta began to advance to the basin as the sea level fell.