Continental rifting and sediment infill in the distal part of the northern South China Sea in the Western Pacific region: Challenge on the present-day models for the passive margins
Continental rifting and sediment infill in the distal part of the northern South China Sea in the Western Pacific region: Challenge on the present-day models for the passive margins
复制标题
西太平洋地区南海北部远端大陆裂谷和沉积物充填：对当今被动边缘模型的挑战
DOI：
10.1016/j.marpetgeo.2018.02.020
复制
发表时间：
2018
影响因子：
4.2
通讯作者：
Han Xiaoying
中科院分区：
文献类型：
--
作者：
Lei Chao;Ren Jianye;Pang Xiong;Chao Peng;Han Xiaoying
众所周知，在西太平洋被深水和厚沉积物覆盖的远端边缘，成像构造和沉积物充填的困难限制了我们解释这些边缘从裂谷到漂移过程的能力。我们利用丰富的多道地震剖面和钻井资料，建立了兴宁-静海凹陷新生代地层的区域地层格架，该凹陷现在位于南中国海视洋壳以北。在我们的调查中，使用大多数标准的识别标准，可以自信地识别出8个层序边界不整合，划分出7个层序地层学。同裂谷序列中地层元素的特殊排列呈现出两种不同的几何沉积组合，其模式与前人所观察到的陆架高角度断裂圈闭的模式不同。兴宁-静海凹陷低角度断裂上盘的地层格局表明，围绕沉积中心的断裂最初是由高角度断裂形成的，这与现今大陆架上的高角度断裂相似。随后深水区高角度断裂转折为伸展拆离小角度断裂，使地壳从∼33 km极薄至∼8~10 km。低角度滑脱断裂系统可用来解释北缘超伸展地壳裂谷后阶段的岩浆补充作用。南中国海超伸展地壳具有陆倾性小角度断裂、高速下地壳和中等岩浆作用的特点，对大西洋边缘构造的贫岩浆或富岩浆模式提出了挑战。
Well-known difficulties in imaging structures and sediment infill in the distal margins covered by deepwater and thick sediment in the western Pacific have limited our ability to interpret rifting-to-drifting processes of these margins. We used a wealth of multi-channel seismic profiles and drilling data to construct a regional stratigraphic framework for the Cenozoic strata in the Xingning-Jinghai Subbasin, which is now located to the north of the apparent oceanic crust in the South China Sea. Eight sequence-bounding unconformities segmented seven sequence stratigraphy can be confidently recognized in our survey using mostly standard criteria for identification. The particular arrangement of strata elements in the syn-rift succession presents two contrast geometry sedimentary packages, whose pattern is different with that bounded by high-angle faults on the continental shelf observed by the previous studies. In the Xingning-Jinghai Subbasin, strata pattern on the hangingwall of the low-angle faults shows that the faults bounding the depocenters were initially formed by high-angle faults, which is similar to the present-day high-angle faults on the continental shelf. Subsequently the high-angle faults in the deepwater region were rotated to be extensional detachment low-angle faults, which extremely thinned the crust from ∼33 km to ∼8–10 km. The low-angle detachment fault systems can be used to explain the magmatic addition during the post-rift stage on the hyper-extended crust in the northern margin. The hyper-extended crust of the South China Sea with the characteristics of landward-dipping low-angle faults, high-velocity lower crust and moderately magmatism challenges the magma-poor or magma-rich models constructed from the Atlantic margins.