红河断裂带北、 中段近期重力变化及深部变形  

STUDY ON PRESENT GRAVITY CHANGE AND DEEP CRUST DEFORMATION IN THE NORTHERN AND MIDDLE SECTIONS OF THE RED RIVER FAULT ZONE

作　　者：汪健[1,2] 申重阳 孙文科[2] 谈洪波 胡敏章[1] 梁伟锋[3] 韩宇飞[4] 张新林 吴桂桔[1] 王青华[5] WANG Jian;SHEN Chong-yang;SUN Wen-ke;TAN Hong-bo;HU Min-zhang;LIANG Wei-feng;HAN Yu-fei;ZHANG Xin-lin;WU Gui-ju;WANG Qing-hua(Key Laboratory of Earthquake Geodesy,Institute of Seismology,China Earthquake Administration,Wuhan 430071,China;College of Earth and Planetary Sciences,University of Chinese Academy of Sciences,Beijing 100049,China;The Second Monitoring and Application Center,China Earthquake Administration,Xi'an 710054,China;China Earthquake Networks Center,Beijing 100045,China;Yunnan Earthquake Agency,Kunming 650041,China)

机构地区：[1]中国地震局地震研究所,地震大地测量重点实验室,武汉430071 [2]中国科学院大学地球与行星科学学院,北京100049 [3]中国地震局第二监测中心,西安710054 [4]中国地震台网中心,北京100045 [5]云南省地震局,昆明650041

出　　处：《地震地质》2021年第6期1537-1562,共26页Seismology and Geology

基　　金：国家自然科学基金(41604014);国家自然科学基金(41674014);国家自然科学基金(41744093);国家自然科学基金(41431069);国家自然科学基金(41674018);国家自然科学基金(U1939204);973项目(2013CB733304);中国地震局地震研究所所长基金(IS201926298)。

摘　　要：地表地质调查与深部地球物理探测结果表明,红河断裂带北、中段地壳结构与变形具有显著的横向差异性。为检测其地壳现今深部物质迁移和变形特征,文中利用红河断裂带北、中段2013—2019年3条流动重力剖面的观测资料,经分析和去除地表垂直运动、地表水循环、剥蚀和冰川均衡调整引起的重力效应,获取了地壳深部物质迁移引起的趋势性重力变化信息。结果表明,红河断裂带近期的重力动态变化具有分段性特征:北段、中段和中南段剖面的平均变化率为(-0.39±1.30)μGal/a、(0.16±1.57)μGal/a和(0.29±1.25)μGal/a,北段剖面以红河断裂为界,NE侧呈负变化、SW侧呈正变化,SW侧相对NE侧以(3.1±0.55)μGal/a·100km的重力变化率增加,反映出青藏高原物质东流背景下深部物质跨越红河断裂带后受澜沧江刚性块体阻挡、质量不断累积的特征;中段剖面断裂带区域的重力变化率比两侧低,体现了红河断裂的深部控制作用;中南段剖面的重力整体呈正变化,反映了印支、华南块体与川滇菱形地块间相互侧向挤压、深部物质累积的性质。基于重力变化反演的莫霍面变形结果表明:近期红河断裂带的莫霍面平均以0.54cm/a的速率持续隆升,北段、中段和中南段的平均变形速率为-0.06cm/a、1.36cm/a、0.32cm/a,在一定程度上反映出区域非均衡构造运动作用;北段莫霍面自东向西由下沉逐渐转为隆升;中段东侧隆升、西侧下沉;中南段变形速率低且两侧差异小;红河断裂带区域的变形速率明显低于两侧地块,体现了其对地壳深部变形较强的边界控制作用。文中的研究结果可为青藏高原东南缘断裂活动性研究提供新的约束。Results of surface geological survey and deep geophysical exploration indicate that there are significant lateral differences in the crustal structure and deformation of the northern and middle sections of the Red River fault zone.In order to detect the current material migration and deformation characteristics in the crust along the Red River fault zone,we analyzed and removed the gravity changes caused by vertical surface movement,surface water circulation,denudation,and glacial isostatic adjustment effects based on mobile gravity observation data of 3 profiles in the northern and middle section of the Red River fault zone from 2013 to 2019,and obtained the trend of gravity change caused by the migration of materials in the deep crust.Based on recent gravity changes and crustal structure models,the deformation characteristics of Moho surface along the northern,middle,and middle-southern sections of the Red River fault zone are inverted.The results of the study are as follows:(1)Average gravity change caused by vertical crustal movement is(-0.11±0.21)μGal/a,(0.22±0.21)μGal/a and(0.16±0.21)μGal/a in the northern,middle and middle-southern sections of the Red River fault zone,respectively.The surface crust of the Red River fault zone and its adjacent areas uplifts globally with a rate of((0.92±1.17)mm/a),which is identical to the background trend of uplift of Qinghai-Tibet plateau.Gravity change caused by the surface water reserves cannot be ignored,and the magnitude of the change is-10~10μGal.Gravity change trends on both sides of the Red River fault zone are accordant,but differences in the middle section are higher than that in the northern section.(2)Recent gravity change of the Red River fault zone has segmental characteristics:The northern section of the Red River fault zone shows a negative gravity change trend with a rate of(-0.39±1.30)μGal/a.Bounded by the Red River fault zone,gravity change in northeastern side of the northern section of the Red River fault zone is negative,while the southweste

关 键 词：红河断裂带 重力变化 重力反演 质量迁移 深部变形 

分 类 号：P315.72[天文地球—地震学]