Shallow anatomy of a continent-ocean transition zone in the northern South China Sea from multichannel seismic data
Shallow anatomy of a continent-ocean transition zone in the northern South China Sea from multichannel seismic data
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DOI：
10.1016/j.tecto.2012.05.027
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发表时间：
2012-07
期刊：
影响因子：
2.9
通讯作者：
Junjiang Zhu;X. Qiu;H. Kopp;Hui-long Xu;Zongxun Sun;A. Ruan;Jinlong Sun;Xiaodong Wei
中科院分区：
文献类型：
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作者：
Junjiang Zhu;X. Qiu;H. Kopp;Hui-long Xu;Zongxun Sun;A. Ruan;Jinlong Sun;Xiaodong Wei
南海新生代构造演化表现为大陆裂陷、海底扩张、俯冲、地壳碰撞和走滑断层运动等多种构造过程。本研究的多道地震资料清晰地显示了南海北部大陆在破碎、裂谷和海底扩张过程中岩石圈伸展形成的陆-海过渡带。陆-海过渡带的形态单元为断陷、火山岩带和倾斜断块。火山岩带是陆-洋过渡带内的最高伸展带，主要分布在南海北部被动边缘的南部斜坡隆起带。地震图像显示，东沙隆起与白云凹陷之间存在着大的盘状正断层。根据表面热流与初始裂陷地壳厚度的关系推断，南海北部被动边缘在过渡带经历了从宽裂谷到窄裂谷的过程。南海大陆边缘的陆-洋过渡带与以往热流观测和ODP站点1148观测到的高热流区（平均90mW.m−2）一致，表现为纵波速度的急剧变化。与世界上典型的被动边缘相比，南海裂谷边缘是非典型的岩浆贫乏被动边缘或介于伊比利亚型非火山与格陵兰型火山边缘之间的中间形态。
The Cenozoic tectonic evolution of the South China Sea is reflected in diverse tectonic processes including continental rifting, seafloor spreading, subduction, terrane collision and strike–slip fault movement. A continent–ocean transition zone in the northern South China Sea caused by the lithospheric extension when the continent underwent break-up, rifting and later seafloor spreading, is clearly imaged in the multi-channel seismic data presented in this study. The morphological units of the continent–ocean transition zone are the rift-depression, the volcanic zone and tilted fault blocks. The volcanic zone represents a highest extension zone within the continent–ocean transition zone and is mainly distributed in the southern slope uplift zone along the northern passive margin of the South China Sea. The large listric-normal faults bounding the Dongsha Rise and Baiyun Sag are evidenced in the seismic image. The passive margin in the northern South China Sea underwent the wide-rift to narrow-rift process in the transition zone as inferred from the relation between the surface heat flow and initial rifted crustal thickness. The continent–ocean transition zone in the continental margin of the South China Sea is consistent with high heat flow zone (average 90mW.m−2) observed in the previous heat flow measurements and at ODP Site 1148, and is manifested in a sharp change of the P-wave velocity. The rifted margin of the South China Sea is a non-typical magma poor passive margin or an intermediary form between the Iberian-type non-volcanic and the Greenland-type volcanic margin compared to the world's typical passive margins.