Hi-Climb测线下速度结构辨识拉萨地体内的构造单元特征及其对青藏高原演化的指示  

Identification of tectonic units within Lhasa terrane in western Tibet by velocity structure along Hi-Climb and its indication for the evolution of the Tibetan Plateau

作　　者：牛潇 贺日政[1,2] 李娱兰 李宗旭 唐晗晗 NIU Xiao;HE Rizheng;LI Yulan;LI Zongxu;TANG Hanhan(Chinese Academy of Geological Sciences,Beijing 100037,China;Laboratory of Deep Earth Sciences and Technology of Ministry of Natural Resources,Beijing 100037,China;School of Earth and Space Sciences,University of Science and Technology of China,Hefei 230026,Anhui,China)

机构地区：[1]中国地质科学院,北京100037 [2]自然资源部深地科学与探测技术实验室,北京100037 [3]中国科学技术大学地球和空间科学学院,安徽合肥230026

出　　处：《地质通报》2024年第11期1970-1984,共15页Geological Bulletin of China

基　　金：中国地质调查局项目《藏北班怒带深部地质调查》(编号:DD20230008);国家自然科学基金项目《主被动源地震学联合探测永珠-那木错蛇绿岩带的壳幔痕迹》(批准号:42074112);国家野外科学观测研究站拉萨站项目《青藏高原拉萨地体中西部发震机制及深部构造研究》(编号:NORSLS23-07);中国地质科学院基本科研业务费项目《青藏高原下的地幔结构差异演化机制及其对资源与能源的影响》(编号:JKYZD202302)、《鑫龙金多金属矿深部成矿结构分析研究》(编号:JKYQN20240)。

摘　　要：印度大陆板块北向俯冲及碰撞导致青藏高原快速隆升。在此过程中,高原内部物质组成及构造演化尤为复杂,其中高原内部低速层分布特征及其构造成因并不明确。收集了Hi-Climb计划北部台站的数据,利用接收函数复谱比非线性反演方法获取剖面的速度结构特征,与已有地球物理的研究结果结合,显示测线下地壳内部低速层被狮泉河-纳木错混杂岩带和班公湖-怒江缝合带(BNS)所分隔,且存在明显差异。研究结果表明,狮泉河-纳木错混杂岩带不仅是中拉萨地体与北拉萨地体间的深大断裂带,还是地幔顶部的重要转换边界带。上地壳低速层分布主要与地表区域构造及沉积层分布有关,中下地壳低速层分布不仅受地体边界的约束,且与青藏高原的隆升相关。The northward collision and subduction of the Indian continental plate have led to the rapid uplift of the Tibetan Plateau.During the uplift process,the material composition and tectonic evolution are highly complicated in the plateau,and the distribution characteristics and tectonic origin of the low-velocity layer within the plateau are not clear.In this paper,we collected data from the northern stations of the Hi-Climb and used the receiver function complex spectral ratio-based nonlinear inversion method to obtain 1-D shear velocity structure.Combining previous geophysical research results,our result show that the shear-wave low-velocity layer in the lower crust beneath the profile is separated by the Shiquanhe-Namco Melange suture zone(SNMZ)and the Bangong-Nujiang suture zone(BNS),and distinctly differ from each other.This result indicates that the SNMZ is a deep fault zone between the Central and North Lhasa terranes,and also an important transition zone at the uppermost mantle.Low-velocity layer in the upper crust is mainly related to the surface geological structure and the distribution of sedimentary layers.Horizontal distribution of the low velocity layer in the middle and lower crust is not only constrained by terrane boundaries,such as SNMZ and BNS,but also related to the uplift of the Tibetan Plateau.

关 键 词：青藏高原 接收函数分析 狮泉河-纳木错混杂岩带 低速层 拉萨地体 

分 类 号：P54[天文地球—构造地质学]