Earth Science Frontiers ›› 2022, Vol. 29 ›› Issue (6): 277-290.DOI: 10.13745/j.esf.sf.2022.8.5

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Late Mesozoic continental arc migration in southern China and its effects on the evolution of offshore forearc basins

ZHU Weilin1(), XU Xuhui2, WANG Bin3, CAO Qian3, CHEN Chunfeng4, GAO Shunli4, FENG Kailong1, FU Xiaowei1,*()   

  1. 1. State Key Laboratory of Marine Geology, Tongji University, Shanghai 200092, China
    2. Sinopec Geophysical Research institute, Nanjing 211103, China
    3. Wuxi Research Institute of Petroleum Geology, Sinopec, Wuxi 214131, China
    4. CNOOC China Limited (Shanghai), Shanghai 200030, China
  • Received:2022-07-07 Revised:2022-08-01 Online:2022-11-25 Published:2022-10-20
  • Contact: FU Xiaowei


Forearc basins are closely linked to continental arcs in a subduction system. In southern China, widespread onshore magmatic belt and offshore forearc basins developed under multi-stage subduction since the Mesozoic. However, the arc migration pattern has been under hot debate, and the related forearc basins are little known because of limited offshore drilling and lack of access to onshore magmatic arc rock. Thus, new research designs are needed to observe the Late-Mesozoic subduction system/processes of southern China based on available data. In this paper, typical offshore wells containing Mesozoic layers are analyzed in detail; tectonics and sedimentation characteristics of offshore basins are systematically compared; and the development of forearc basins is analyzed in combination with the arc migration. Results show that the arc system extends roughly along the present-day coast of southern China from the Early Jurassic to Early Cretaceous: It mainly distributes in the southern East China Sea and extends to the northeastern South China Sea region in the Early Jurassic, then spreads widely southwards to the South China Sea in the Middle-Late Jurassic; since the Early Cretaceous it migrates eastward due to rollback of the subducted Paleo-Pacific slab. During this arc migration process, forearc basins are finally formed in the Middle Jurassic. And in response to the trenchward arc migration, angular unconformities in all forearc basins are formed and coarse clastic facies migrate trenchward in the Early Cretaceous. In the Late Cretaceous, the northern China Sea region is no longer in the subduction system and the forearc basin is replaced by regional unconformity; meanwhile, the East China Sea Basin becomes a backarc basin. Forearc basin evolution is primarily controlled by the migrating arc system, thus Mesozoic basins in the offshore South China Sea can provide important constraint on the regional arc migration pattern.

Key words: South China block, Mesozoic, forearc basin, continental arc, subduction system

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