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南海北部陆缘的构造属性问题

吴世敏, 周 蒂, 丘学林   

  1. 中国科学院南海海洋研究所,广州 510301
  • 收稿日期:2001-12-20 修回日期:2001-12-20 出版日期:2001-12-20 发布日期:2001-12-20

Tectonic Setting of the Northern Margin of South China Sea

WU Shi-min, ZHOU Di, QIU Xue-lin   

  1. South China Sea Institute of Oceanology, CAS, Guangzhou 510301, China
  • Received:2001-12-20 Revised:2001-12-20 Online:2001-12-20 Published:2001-12-20

摘要: 以1号断裂为界,南海北部陆缘可分为东,西两段:东段包括北部湾盆地,琼东南盆地,珠江口盆地和台西盆地等,西段包拓莺歌海盆地。两者构造形变特征存在一定的差异性:东段盆地边界断层主要为NE-EW向,为分支断层通过不同类型转换坡连接而成的多支正断层系,因断层位移沿走向有规律变化,在其上盘发育相关褶皱,如横向褶皱;西段盆地边界断层也是由多条分支断层连接的多支断层系,但方向为NW向,以走滑作用为主,上盘没有发育断层相关褶皱。结合新生代岩浆作用,沉降和充填作用及地壳结构等特征分析,南海北部陆缘东段在构造活动上可以分成三个相对活跃时期,即50-40,30-28和10-5Ma左右。每一期拥有各自的特点,并具有不同的动力学来源,前两期与南海的扩张关系密切,3则与南海扩张无成因联系。南海北部陆缘虽然有一定的岩浆活动,但不是张烈的同期产物,因而它在形成机制上属于非火山型被动大陆边缘,其活动性因素是受周边板块相互作用的叠加所致。西段从成因机制上来讲并不属于南海北部陆缘,可能与印-藏碰撞关系更为密切。

Abstract: There are different deformation characteristics between the east and west part of the number 1 fault in the northern margin of South China Sea(SCS). The east part includes the Beibuwan basin, Qiongdongnan basin, Zhujiangkou basin and Taixi basin, with NE-EW strike segment of normal faults and traverse fold. The west part includes Yinggehai basin, with NW strike transtensiona1 faults. Based on with the features of magmatics, subsidence, sedimentary fill, crust structure in the northern margin of SCS, the authors believe that the east part margin exist three relative tectonic active periods, i.e. 40—50, 28—30, 10—5Ma. They exhibited different dynamics characteristic respectively.The former two episodes are related to the break up processing of SCS. The third is nothing to do with it. The magmatics at the northern margin of SCS are not the correspond activity with the rifting of SCS. Therefore, the east part of the northern margin of SCS belongs to the non-volcanic passive margin according to its forming mechanism. The active factors are overlapped by the interaction of surrounding plates. The west part may be related to the collision of India-Tibet and it is not a part of the northern margin based on the formation mechanism.