The tectonic evolution of the Qiongdongnan Basin in the northern margin of the South China Sea |
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| Institution: | 1. State Key Laboratory for Mineral Deposits Research, School of Earth Science and Engineering, Nanjing University, No.163 Xianlin Road, Qixia District, Nanjing 210046, Jiangsu, China;2. Key Laboratory of Coast and Island Development, MOE, School of Geographic and Oceanographic Sciences, Nanjing University, No.163 Xianlin Road, Qixia District, Nanjing 210046, Jiangsu, China;3. China National Offshore Oil Corporation, 25 Chaoyangmenbei Dajie, Dongcheng District, Beijing 100010, China;4. CNOOC Research Center, 6 Dongzhimenwai Xiaojie, Dongcheng District, Beijing 100027, China;5. CNOOC Nanhai West Corporation, P.O. Box 11, Potou District, Zhanjiang, Guangdong Province 524057, China;1. College of Energy Resources, Chengdu University of Technology, Chengdu, Sichuan, 610059, PR China;2. State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation, Chengdu University of Technology, Chengdu, Sichuan, 610059, PR China;3. China Energy Reserve Corporation, Beijing, 100107, PR China;4. Ocean College, Zhejiang University, Hangzhou, 310058, PR China;5. State Key Laboratory of Petroleum Resources and Prospecting, China University of Petroleum (Beijing), Beijing, 102249, PR China;1. Ecole Normale Supérieure de Paris, UMR 8538, 24 rue Lhomond, 75005, Paris, France;2. UniversitiTechnologiPetronas, SDN, BHD, Bandar Seri Iskandar, 31750, Tronoh, Perak DarulRidzuan, Malaysia;3. Federal Institute for Geosciences and Natural Ressources (BGR), Stilleweg 2, D-30655, Hannover, Germany;4. TOTAL, Tour Coupole, 2, Place de la Coupole, F-92078, Paris La Défense CEDEX, France;1. Key Laboratory of Petroleum Resources Research, Institute of Geology and Geophysics, Chinese Academy of Sciences, Lanzhou 730000, China;2. Research Institute of China National Offshore Oil Corporation, Beijing 100028, China;3. University of Chinese Academy of Sciences, Beijing 100049, China;1. Institute of Deep-sea Science and Engineering, Chinese Academy of Sciences, Sanya 572000, China;2. Key Laboratory of Marginal Sea Geology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou 510301, China;3. Laboratory for Marine Mineral Resources, Qingdao National Laboratory for Marine Science and Technology, Qingdao 266071, China;1. CAS Key Laboratory of Ocean and Marginal Sea Geology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou 510301, China;2. MARUM – Center for Marine Environmental Sciences, University of Bremen, Germany |
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| Abstract: | Qiongdongnan Basin is a Cenozoic rift basin located on the northern passive continental margin of the South China Sea. Due to a lack of geologic observations, its evolution was not clear in the past. However, recently acquired 2-D seismic reflection data provide an opportunity to investigate its tectonic evolution. It shows that the Qiongdongnan Basin comprises a main rift zone which is 50–100 km wide and more than 400 km long. The main rift zone is arcuate in map view and its orientation changes from ENE–WSW in the west to nearly E–W in the east. It can be divided into three major segments. The generally linear fault trace shown by many border faults in map view implies that the eastern and middle segments were controlled by faults reactivated from NE to ENE trending and nearly E–W trending pre-existing fabrics, respectively. The western segment was controlled by a left-lateral strike-slip fault. The fault patterns shown by the central and eastern segments indicate that the extension direction for the opening of the rift basin was dominantly NW–SE. A semi-quantitative analysis of the fault cut-offs identifies three stages of rifting evolution: (1) 40.4–33.9 Ma, sparsely distributed NE-trending faults formed mainly in the western and the central part of the study area; (2) 33.9–28.4 Ma, the main rift zone formed and the area influenced by faulting was extended into the eastern part of the study area and (3) 28.4–20.4 Ma, the subsidence area was further enlarged but mainly extended into the flanking area of the main rift zone. In addition, Estimates of extensional strain along NW–SE-trending seismic profiles, which cross the main rift zone, vary between 15 and 39 km, which are generally comparable to the sinistral displacement on the Red River Fault Zone offshore, implying that this fault zone, in terms of sinistral motion, terminated at a location near the southern end of the Yinggehai Basin. Finally, these observations let us to favour a hybrid model for the opening of the South China Sea and probably the Qiongdongnan Basin. |
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| Keywords: | Qiongdongnan Basin Fault pattern Rift segment Pre-existing structural fabrics South China Sea |
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