Source-to-Sink System Analysis of the Meishan Formation Turbidite Fans in the Northwest of the Central Depression of the Qiongdongnan Basin, Southern China Sea

Large and medium-sized gas fields such as Lingshui 17-2 have been discovered in the Miocene Huangliu Formation and Pliocene Yinggehai Formation in the central depression of the Qiongdongnan Basin. However, due to poor understanding of sand body distribution and sand-controlling mechanism, no significant breakthrough has been made in the exploration of the mid-deep Meishan Formation so far. Therefore, this paper focuses on the turbidite fan sandstones of the Meishan Formation in the northwest of the central depression in the Qiongdongnan Basin and analyzes the key elements of the source-to-sink system as well as sand-controlling mechanism through petrographical microanalysis, rock and mineral composition statistics and isotope testing, combined with macroscopic tectonic evolution and river development carving. The result reveals that the turbidite fans of well A were transported and deposited from NW to SE along the No.1 fault, the No.13 fault and multi-period channels of the Red River fault zone with multi-provenance supply from the Hainan Island, the central Vietnam and the Red River. The turbidite fans of well B and C were transported and deposited from NNW to SSE along the No. 5 fault, the No. 3 fault, the No. 2 fault and multi-period channels with provenance supply from the Hainan Island. The turbidite fans of well D were transported and deposited from NE to SW along the No. 5 fault, the No. 6 fault, the No. 2 fault and multi-period channels with different branches of provenance supply from the Hainan Island. The source-to-sink system of the Meishan Formation in the northwestern central depression of the Qiongdongnan Basin is absolutely controlled by the provenance of the Hainan Island, which is characterized by multi-provenance supply from the Hainan Island, the Red River and the central Vietnam, converging along the inherited active faults as well as multi-period channels, and being deposited at the bottom of submarine fans. The northeast of A and D turbidite fans is a favorable zone for the turbidite sand body development of the Meishan Formation in the northwest of the central depression in Qiongdongnan Basin.