青藏高原及周边地区的重磁异常多尺度横向构造分析  

Multiscale lateral structural analysis of gravity and magnetic anomalies in Tibetan Plateau and adjacent areas

作　　者：王再骄 高国明[1] 李业成 WANG Zaijiao;GAO Guoming;LI Yecheng(Department of Geophysics,School of Earth Sciences,Yunnan University,Kunming 650500,Yunnan,China)

机构地区：[1]云南大学地球科学学院地球物理系,云南昆明650500

出　　处：《云南大学学报(自然科学版)》2025年第1期79-87,共9页Journal of Yunnan University(Natural Sciences Edition)

基　　金：国家自然科学基金(41964004);云南省基础研究计划面上项目(202101AT070181);云南大学第15届研究生科研创新项目(KC-23233745)。

摘　　要：青藏高原深部构造特征和地球动力学问题一直是地球科学研究的热点,目前仍存在诸多争论.文章基于全球最新高精度的EMAG2磁异常模型、SGG-UGM-2重力场模型和ETOPO 2022地形模型,分析青藏高原及周边地区的重磁异常空间展布特征,并采用频率域优化滤波方法,对不同深度重磁异常场的横向构造特征进行深入研究.结果表明:①重磁异常空间展布图显示,青藏高原整体呈现弱的或负的磁异常和强的负布格重力异常,周边地块表现为强的正磁异常和正布格重力异常,重磁异常空间展布与该区域的岩石圈构造特征基本一致;②低频重磁异常信息的结果显示,青藏高原深部物质温度高、密度低,软弱的熔融物质膨胀上涌造成了地壳的隆升与增厚;③中等尺度的磁异常信息显示,青藏高原中下地壳流自西向东流动,受到周围块体的阻挡,逐渐向东南方向流出;④中等尺度的布格重力异常信息显示,印度板块向北俯冲的边界在西部到达了可可西里块体西部、帕米尔高原东部、龙木错—独立石湖断裂附近;中部到达了班公错断裂、巴措断裂、雅鲁藏布江断裂、怒江断裂一带;东部俯冲到了羌塘块体和松潘—甘孜块体的东部地区.The deep structural characteristics and geodynamic issues of Tibetan Plateau have long been a hot topic in Earth sciences,with many controversies still unresolved.This study analyzes the spatial distribution of gravity and magnetic anomalies in Tibetan Plateau and its surrounding areas,based on such latest high-resolution global models as the EMAG2 magnetic anomaly model,the SGG-UGM-2 gravity field model,and the ETOPO 2022 topography model.Additionally,the optimized frequency-domain filtering methods are applied to conduct an in-depth study on the lateral structural features of gravity and magnetic anomaly fields at different depths.The results show that:①The spatial distribution map of gravity and magnetic anomalies demonstrates that Tibetan Plateau exhibits weak or negative magnetic anomalies and strong negative Bouguer gravity anomalies,while the surrounding blocks display strong positive magnetic anomalies and positive Bouguer gravity anomalies.The spatial distribution of gravity and magnetic anomalies is generally consistent with the lithospheric structural characteristics of the region.②The results of low-frequency gravity and magnetic anomalies reveal that the deep material beneath Tibetan Plateau has high temperatures and low densities,and the expansion and upwelling of weak molten material have caused crustal uplift and thickening.③The medium-scale magnetic anomaly data indicate that the middle and lower crust flow in Tibetan Plateau moves from west to east,but is obstructed by surrounding blocks and gradually flows southeastward.④The medium-scale Bouguer gravity anomaly data suggest that,in the west,the northern subduction boundary of the Indian Plate reaches the west of Hoh Xil block,the east of Pamir Plateau,and the Longmu Co‒Shihu suture;its central part extends to the Bangong Co fault,Bacho fault,Yarlung Tsangpo fault,and Nujiang fault;and its east reaches the eastern regions of the Qiangtang block and Songpan‒Ganzi block.

关 键 词：重力异常 磁异常 优化滤波 青藏高原 

分 类 号：P318[天文地球—固体地球物理学]