[Objective]The middle Miocene submarine fan in the Qiongdongnan Basin is an important target for natural gas exploration in the northern South China Sea. However, for a long time, there has been no consensus on the source of the submarine fan sediments, The provenance analysis will be of great significance to the optimization of natural gas exploration in this area. [Methods]In this paper, the detrital zircon U—Pb age spectrum characteristics of drilling cores of the middle Miocene submarine fan in the Qiongdongnan Basin was analyzed and compared with the U—Pb age of the zircon in the potential provenance area to trace the source of submarine fan in the study area. [Results]The results show that : ①The U—Pb ages of detrital zircons from N-1, N-2, N-3 and N-4 wells in the northern part of the basin are characterized by the age peaks of Yanshanian (160 Ma, 157 Ma, 133 Ma, 107 Ma, 102 Ma, 99 Ma), Indosinian ( 249 Ma, 241 Ma, 239 Ma ) and Caledonian ( 466 Ma, 455 Ma ), and have high similarity with the U—Pb age characteristics of detrital zircons from the Hainan Island sediments, but with low similarity with the U—Pb age characteristics of detrital zircons from Red River and central Vietnam sediments. ②The detrital zircon U—Pb age characteristics of three wells ( S-1, S-2, S-3 ) in the southern part of the basin show the peak age characteristics of Indosinian ( 242 Ma, 238 Ma, 237 Ma ), Caledonian (431 Ma, 431 Ma, 425 Ma,), Hercynian (392 Ma, 392 Ma) and Yanshan ( 143 Ma ). The S-2 well has a younger unimodel Himalayan ( 21 Ma ) age peak. [Conclusion] It is confirmed that the sediment source of the middle Miocene in the northern part of the basin is mainly from Hainan Island. The influence of the provenance in the Red River and Central Vietnam are very limited. The provenance of the middle Miocene in the southern Qiongdongnan Basin has a double-source supply from the Red River and Hainan Island, and is dominated by the former one, with an apparent difference from west to east.
DownLoad: