山西断陷带及其邻区背景噪声面波直接反演成像  

Direct Surface-wave Tomography from Ambient Noise in the Shanxi Rift Zone and Adjacent Areas

作　　者：张浩 雷建设 宋晓燕 邓玥[3] ZHANG Hao;LEI Jianshe;SONG Xiaoyan;DENG Yue(College of Coal Engineering,Datong University,Datong 037000,China;National Institute of Natural Hazards,Ministry of Emergency Management of China(Key Laboratory of Crustal Dynamics),Beijing 100085,China;School of Information Engineering,Inner Mongolia University of Technology,Hohhot 010010,China)

机构地区：[1]山西大同大学煤炭工程学院,山西大同037000 [2]应急管理部国家自然灾害防治研究院地壳动力学重点实验室,北京100085 [3]内蒙古工业大学信息工程学院,呼和浩特010010

出　　处：《CT理论与应用研究(中英文)》2025年第2期175-189,共15页Computerized Tomography Theory and Applications

基　　金：应急管理部国家自然灾害防治研究院科技创新团队(2023-JBKY-55);应急管理部国家自然灾害防治研究院基本科研业务专项(ZDJ2024-28);国家自然科学基金(U1939206);内蒙古自治区自然科学青年基金(2024QN04011);内蒙古工业大学科学研究(ZY201901)。

摘　　要：山西断陷带是世界上最活跃的新生代大陆裂谷之一,获得该地区地壳精细三维S波速度结构有助于了解大陆裂谷的形成机制。本研究利用2021年1月至2022年12月期间山西、内蒙、河北、河南和陕西等地布设的113个省级固定台站记录的连续波形数据,提取5~40 s周期范围共4 951条高质量瑞利波相速度频散曲线,采用面波直接反演成像法,获得山西断陷带及其周边地区地壳0~40 km深度的三维S波速度结构。结果表明:5 km深度处的S波速度结构与地表断陷带分布和沉积层厚度存在一定相关性,断陷带整体呈低速异常特征,两侧隆起区为高速异常;随着深度的增加,低速异常区域有所减少,且低速异常从地表一直延伸至15 km深度左右;从25 km深度开始,山西断陷带中南部的太原盆地、临汾盆地和运城盆地由上地壳的低速异常转为下地壳的高速异常,并持续延伸至上地幔顶部,可能为盆地拉张之前第三纪早期的玄武岩岩浆底侵冷却所致;大同火山区的低速异常从上地幔顶部持续延伸至地壳20 km深度左右,并由西向东转移,较清晰地揭示出大同火山下方的岩浆上涌通道;北纬38°以北大面积的低速异常推测可能为新生代以来大同火山大量的火山活动引起地壳升温导致部分熔融形成。本研究获得的研究区地壳三维高分辨率S波速度结构为进一步理解大陆裂谷的形成机制提供了新的地震学证据。The Shanxi rift zone is one of the most active continental rift zones in the world.Obtaining a fine three-dimensional S-wave velocity structure of the crust in this region helps understand the formation mechanism of continental rifts.In this study,continuous waveform data recorded at 113 fixed provincial stations deployed in Shanxi,Inner Mongolia,Hebei,Henan,and Shaanxi between January 2021 and December 2022 were utilized.A total of 4 951 high-quality Rayleigh wave phase velocity dispersion curves in the 5 ~ 40 s period range were extracted.Using the direct surface wave imaging method,a three-dimensional S-wave velocity structure of the crust in the Shanxi rift zone and surrounding areas at depths of 0 ~ 40 km was obtained.The results show that the Swave velocity structure at a depth of 5 km correlates with the distribution of surface fault zones and thickness of the sedimentary layers.Rift zones generally exhibit low-velocity anomalies with high-velocity anomalies on both sides of the uplift areas.As depth increases,the low-velocity anomaly gradually decreases,with low-velocity zones extending from the surface to approximately 15 km depth.At a depth of 25 km,the low-velocity anomalies in the central and southern parts of the Shanxi rift zone,including the Taiyuan,Linfen,and Yuncheng basins,transitioned from the upper crust to high-velocity anomalies in the lower crust,extending to the top of the upper mantle.This may have been caused by cooling of the basaltic magma intruding beneath the basins during the early Tertiary period before rifting.In the Datong volcanic region,the low-velocity anomaly extends from the top of the upper mantle to approximately 20 km depth in the crust and shifts from west to east,clearly revealing the magma upwelling pathway beneath Datong.A large low-velocity anomaly north of 38°N was inferred to have been caused by crustal heating and partial melting due to extensive volcanic activity in the Datong volcanic region since the Neogene.The high-resolution three-dimensional S-wave velocit

关 键 词：背景噪声成像 S波速度结构 山西断陷带 大同火山 

分 类 号：P315[天文地球—地震学] P542[天文地球—固体地球物理学]