| Citation: |
Xu-wen Qin, Bin Zhao, Fu-yuan Li, Bao-jin Zhang, Hou-jin Wang, Ru-wei Zhang, Jia-xiong He, Xi Chen, 2019. Deep structural research of the South China Sea: Progresses and directions, China Geology, 2, 530-540. doi: 10.31035/cg2018125
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Deep structural research of the South China Sea: Progresses and directions
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Abstract
The South China Sea (SCS) is the hotspot of geological scientific research and nature resource exploration and development due to the potential for enormous hydrocarbon resource development and a complex formation and evolution process. The SCS has experienced complex geological processes including continental lithospheric breakup, seafloor spreading and oceanic crust subduction, which leads debates for decades. However, there are still no clear answers regarding to the following aspects: the crustal and Moho structure, the structure of the continent-ocean transition zone, the formation and evolution process and geodynamic mechanism, and deep processes and their coupling relationships with the petroliferous basins in the SCS. Under the guidance of the “Deep-Earth” science and technology innovation strategy of the Ministry of Natural Resources, deep structural and comprehensive geological research are carried out in the SCS. Geophysical investigations such as long array-large volume deep reflection seismic, gravity, magnetism and ocean bottom seismometer are carried out. The authors proposed that joint gravity-magnetic-seismic inversion should be used to obtain deep crustal information in the SCS and construct high resolution deep structural sections in different regions of the SCS. This paper systematically interpreted the formation and evolution of the SCS and explored the coupling relationship between deep structure and evolution of Mesozoic-Cenozoic basins in the SCS. It is of great significance for promoting the geosystem scientific research and resource exploration of the SCS.
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References
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Xu-wen Qin, Bin Zhao, Fu-yuan Li, Bao-jin Zhang, Hou-jin Wang, Ru-wei Zhang, Jia-xiong He, Xi Chen, 2019. Deep structural research of the South China Sea: Progresses and directions, China Geology, 2, 530-540. doi: 10.31035/cg2018125
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Figure 1.
Regional geological and geodynamic framework of the SCS, modified from Lebedev S and Nolet G (2003), Wang PC et al. (2017) and Zhao B et al., 2019a; The magnetic anomalies are modified from Taylor B and Hayes DE (1980, 1983), Briais A et al. (1993). ZI−Zhongsha Islands; XI−Xisha Islands; NWSB−Northwest sub-basin; ESB−East sub-basin; SWSB−Southwest sub-basin; ASRR−Ailaoshan-Red River shear zone; ZNF−Zhongnan fault.
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Figure 2.
Paleogeographic reconstructions of SE Asia. a−Approximately 16 Ma, prior to the end of the SCS seafloor spreading; b−approximately 32 Ma, prior to onset of the SCS seafloor spreading, modified from Leloup PH et al. (2001). India-Asia collision model. A large-scale sinistral strike-slip occurred in the Ailaoshan-Red River shear zone between 32−16 Ma. The time of the strike-slip coincided with the time of the formation of the SCS, and the distance of the strike-slip coincided with the expansion of the SCS.
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Figure 3.
Map view of Hainan plume by P-wave velocity perturbations (in %), modified from Lei J et al. (2009). Hainan plume beneath Hainan island, extending from the surface down to 250 km depth with a diameter of about 80 km. The section location sees Fig. 1.
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Figure 4.
Deep-interior geological and geophysical investigation in SCS. ESP, Expanding spread profile; MCS, Multichannel seismic; OBS, Ocean bottom seismometer; LH OBS, Joint onshore-offshore seismic prospect; OBS 3D, three-dimensional OBS; Ocean drilling program (ODP)/IODP sites modified from Wang PX (2019); OBS survey lines refer to Yan P et al. (2001), Qiu XL et al. (2001, 2011), Wu SM et al. (2009), Wang TK et al. (2006), and Zhao MH et al. (2010, 2011, 2018a, 2018b); OBS 3D exploration refer to Zhao MH et al. (2018b); LH OBS refer to Xu HL et al. (2012), Qiu XL et al. (2003) and Huang HB et al. (2011); ESP lines refer to Yao BC et al. (1994) and Nissen SS et al. (1995); Red dashed MCS lines refer to internal data of Guangzhou Marine Geological Survey, the black dashed MCS lines (N3, N4) refer to Ding WW et al. (2018).
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Figure 5.
a−Bouguer gravity anomaly map of the SCS; b−Moho undulations of the SCS derived from the gravity inversion method, modified from Yang SX et al. (2015).
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Figure 6.
Continental breakup and seafloor spreading model of the SCS, modified from Larsen HC et al. (2018) and Ding WW et al. (2018). a−A deep basin with thin crust existed within the final zone of plate rupture and hosted magmatism at the Eocene-Oligocene transition. b−ascending melts rapidly weakened the mantle lithosphere. c−seafloor spreading initiated at 32 Ma, the first ridge jump occurred at about 27 Ma. d−seafloor spreading continued. The second southward ridge jump event occurred at about 23.6 Ma. e−seafloor spreading final cessation at about 16 Ma.The locations of magnetic anomalies and abandoned spreading ridges are shown in Fig. 1.
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Figure 7.
Deep processes and their coupling relationships with the petroliferous basins in the SCS, modified from Lu BL et al. (2016).