| 南沙西南部下地壳高速层成因 |
| |
| 引用本文： | 李凯,沈传波,谢晓军,赵志刚,彭希,周延冰.南沙西南部下地壳高速层成因[J].地球科学,2019,44(3):810-821. |
| |
| 作者姓名： | 李凯 沈传波 谢晓军 赵志刚 彭希 周延冰 |
| |
| 作者单位： | 1.中国地质大学构造与油气资源教育部重点实验室, 湖北武汉 430074 |
| |
| 基金项目： | 国家自然科学基金重大研究计划项目91528303 |
| |
| 摘 要： | 高速层成因的争议限制了对南海深部结构、构造演化以及南海完整演化历史的认识.运用Oasis Montaj软件对穿越南沙西南部的最新地震测线进行重震联合反演，分析莫霍面起伏、地壳厚度及高速层的分布，计算全壳伸展因子和现今高速层的温度、识别火山时代，并探讨高速层的成因.南薇西盆地和礼乐盆地区伸展因子为1.5~4.0，未达到蛇纹石发育条件；南沙海槽区伸展因子大，最大为11.2，海水可通过深大断裂下渗与橄榄岩反应生成蛇纹石，高速层处温度低于蛇纹石稳定温度；通过地震剖面确定火山在南海停止扩张之后形成.研究结果表明，南沙西南部高速层按成因分为两类，南薇西盆地和礼乐盆地区为南海扩张停止后火山喷发残余的岩浆，而南沙海槽盆地区为早期橄榄岩的蛇纹石化与南海停止扩张后岩浆的混合体.
|
| 关 键 词： | 南沙 深部结构 高速层 火山 伸展因子 蛇纹石化 海洋地质 |
| 收稿时间： | 2018-10-12 |
Origin of High Velocity Layer in Lower Crust of Southwestern Nansha Block |
| |
| Abstract: | The controversy over the genesis of the high velocity layer limits the understanding of the deep structure, tectonic evolution and complete evolution of the South China Sea.In order to understand the origin of high velocity layer in the lower crust of the southwestern Nansha block, the joint inversion of gravity and seismic data was performed by using Oasis Montaj software in this study.The seismic profile is across the southwestern Nansha Block.The Moho undulation, crustal thickness and the distribution of the high velocity layer are recorded.The regional extension factor and the temperature at the high layer depth are calculated, and the age of volcanic eruption is determined by seismic features.The whole crustal stretching factor of the Nanweixi Basin and the Liyue Basin area is 1.5-4.0, which is impossible to develop serpentine.The whole crustal stretching factor is up to 11.2 in the Nansha trough.The serpentine is formed by the reaction of peridotite and sea water which enters the mantle through the fractures.The temperature near the high velocity layer is lower than the stable temperature of the serpentine.The volcanic eruption was found in the same place in the seismic profile, and the volcano formed after the cessation of the spreading of the South China Sea.The results indicate that the high velocity layer of the southwestern Nansha Block can be divided into two types.The high velocity layer in the Nanweixi and the Liyue basins is formed by volcanic eruption after the cessation of the spreading of the South China Sea; and the other section in the Nansha trough basin is a mixture of serpentinized peridotite and late magma. |
| |
| Keywords: | |
| 本文献已被 CNKI 等数据库收录！ |
| 点击此处可从《地球科学》浏览原始摘要信息 |
|
点击此处可从《地球科学》下载全文 |
|
