南海打开模式:右行走滑拉分与古南海俯冲拖曳

发布时间：2018-06-19 14:22

本文选题：南海 + 盆地群　；参考：《地学前缘》2017年04期

【摘要】：南海作为东亚大陆边缘最大的边缘海,位于太平洋、印澳和欧亚三个板块的夹持之下,处于特提斯构造域和太平洋构造域的联合作用部位,是揭示新生代两大动力学体系交接转换特征的良好场所。南海海盆为菱形洋盆,包括西北次海盆、东部次海盆和西南次海盆,均在古近纪—中中新世形成,同时伴随着南海北部、西部和南部盆地群发育,盆地边缘油气资源丰富,被称为第二个"波斯湾"。本文搜集了前人对南海洋盆深部形态、磁条带、转换断层等成果,以及南海周边盆地群的沉积体系、沉积相、不整合面相关资料,综合对比了南海北部、西部和南部盆地群的沉积序列、沉积相、沉积厚度,厘定了盆地群断裂体系、断裂组合特征,揭示了南海北部、南部盆地群及西部盆地群中的中建南和万安盆地都是在右行右阶走滑拉分背景下形成的。北部盆地群新生代古近系西厚东薄,新近系东厚西薄,NNE—NE向断裂体系活动早期西强东弱,而晚期东强西弱,从西向东依次停止。同时指出,南海是在NNE向断裂体系右行右阶走滑拉分和古南海俯冲拖曳的联合作用下打开:于34~32 Ma西北次海盆和东部次海盆受控于NNE向断裂的右行右阶走滑拉分作用,沿着NNE-SSW方向开启;32~23 Ma,NNE向走滑断裂活动自西向东逐步停止;于23 Ma左右,"消失"的南海以西的NNE向走滑断裂完全停止活动,同时由于婆罗洲地块逆时针旋转,古南海的俯冲带走向由近E-W向变为NE向,俯冲板块拖曳力也转变为NW-SE向并且占据主导地位,在拖曳力作用下礼乐—巴拉望地块后缘陆壳伸展,导致西南次海盆打开,东部次海盆的扩张方向由NNE-SSW转变为NW-SE向。于15Ma,礼乐—巴拉望地块与婆罗洲地块碰撞,南海停止扩张。
[Abstract]:The South China Sea, as the largest marginal sea in the continental margin of East Asia, is located under the clamping of the Pacific, Indo-Australian and Eurasian plates, and is in the joint position of the Tethys tectonic domain and the Pacific tectonic domain. It is a good place to reveal the characteristics of the transition between the two dynamic systems of the Cenozoic. The South China Sea basin is a diamond-shaped ocean basin, including the northwest subbasin, the eastern subbasin and the southwest subbasin, all formed in Paleogene and Miocene, and accompanied by the development of basin groups in the north, west and south of the South China Sea, the margin of the basin is rich in oil and gas resources. It is called the second Persian Gulf. In this paper, we have collected the data of the South China Sea basin's deep morphology, magnetic stripe, transition fault, and the sedimentary system, sedimentary facies and unconformity surface of the basin group around the South China Sea, and comprehensively compared the north of the South China Sea. The sedimentary sequence, sedimentary facies and thickness of the western and southern basin groups determine the fault system and fault assemblage characteristics of the basin group, and reveal the northern part of the South China Sea. In the southern basin group and the western basin group, the Zhongjian Nan and Wan'an basins were formed in the right strike-slip pull setting. The Cenozoic Paleogene of the northern basin group is thick and thin in the west, and the NNE-NE fault system in the Neogene is weak in the early stage, but weak in the east and west in the late period, and stops successively from west to east. At the same time, it is pointed out that the South China Sea was opened under the combined action of the right-hand strike-slip pull of the NNE-trending fault system and the subduction and towing of the Paleo-South China Sea: the north-west subbasin and the eastern subbasin were controlled by the right-lateral strike-slip pull of the NNE trending fault at 3432 Ma. Along the NNE-SSW direction, the NNE strike-slip fault started in the direction of NNE-SSW and stopped gradually from west to east, and at about 23 Ma, the NNE strike-slip fault to the west of the "vanishing" South China Sea was completely stopped, and because of the counterclockwise rotation of the Borneo block, The trend of the subduction zone in the ancient South China Sea changed from near E-W to NE, and the drag force of subduction plate also changed to NW-SE and occupied the dominant position. Under the action of drag force, the continental crust of the back edge of the Lee-Palawan block was extended, which led to the opening of the southwestern subbasin. The spreading direction of the eastern subbasin changed from NNE-SSW to NW-SE. The South China Sea ceased to expand at 15 Ma, when the Lele-Palawan block collided with the Borneo block.
【作者单位】：海底科学与探测技术教育部重点实验室中国海洋大学海洋地球科学学院;青岛海洋科学与技术国家实验室海洋地质过程与环境功能实验室;
【基金】：国家自然科学基金杰出青年基金项目(41325009);国家自然科学基金项目(41402172,41502185,41502321;U1606401) 山东省泰山学者特聘教授项目鳌山卓越科学家计划项目(2015ASTP-0S10) 国家海洋局重大专项(GASI-GEOGE-01)
【分类号】：P736.1

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