南海的基本构造特征与成因模型:问题与进展及论争

BASIC STRCUTURAL PATTERN AND TECTONIC MODELS OF THE SOUTH CHINA SEA: PROBLEMS, ADVANCES AND CONTROVERSIES

  • 摘要: 南海位于欧亚、印澳、太平洋三大板块交接部位,是东亚大陆边缘最大的边缘海,其大陆边缘经历了复杂的类型转换:北部80 Ma左右为安第斯型大陆边缘,于始新世逐步转变为裂陷边缘,中中新世以来逐步转变为典型被动陆缘;东侧17 Ma前为开放的海域,6 Ma以来逐渐以沟弧盆系统的俯冲带为界,成为半封闭海盆,由单向俯冲演变为双向俯冲;西界自34 Ma以来逐渐转变为走滑型或转换型大陆边缘;南界34 Ma前为与北部对应的不对称裂陷型大陆边缘,34~16 Ma为被动陆缘,16 Ma以后逐渐为俯冲消减型大陆边缘。南海成因的动力学背景复杂,有多种成因争论。板块动力因素既有东侧太平洋板块俯冲、菲律宾板块楔入的影响,又有西侧印度洋板块斜向俯冲、洋中脊俯冲,还可能有北侧青藏高原隆升、大陆块体挤出的影响;同时,深部底侵、拆沉、地幔柱、地幔水化过程等地幔动力学背景也不可忽视。

     

    Abstract: The South China Sea is located at a juncture among the Eurasian, the Indian-Australian and the Pacific plates, being the largest continental marginal sea along the East Asian continental margin. It has experienced a complex transition of continental marginal types. The northern margin was an Andean-type continental margin before 80 Ma, then gradually transferred into a rifted continental margin in the Eocene and a typical passive continental margin since the middle Miocene. The eastern margin was an open water before 17 Ma and gradually became a subduction zone of the trench-arc-basin system by one-way subduction to double-way subduction, when the South China Sea became semi-closed basin since 6 Ma. The western boundary gradually transformed into a continental margin with strike-slipping faulting or transform faulting since 34 Ma. The southern margin was an asymmetric rift-type continental margin corresponding to the northern margin before 34 Ma, and became a passive continental margin during 34~16 Ma and gradually a thrusting-type continental margin after 16 Ma. Complex dynamic settings of the South China Sea have caused many controversies on their origin. The plate dynamic factors include either the Pacific Plate subduction and the indentation of the Philippine Sea Plate along the Taiwan Orogen to the east side the South China Sea, or the Indian Plate oblique subduction and mid-ocean ridge subduction to the west side. They may also be responsible for the uplifting of the Tibetan Plateau and the related extrusions of continental blocks to the north side. At the same time, the mantle dynamics of deep-seated magma underplating, delamination, mantle plume and mantle-hydrated process should not be ignored.

     

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