利用接收函数频率特征研究青藏高原东北缘地区的莫霍面性质  

CONSTRAINING MOHO CHARACTERISTICS IN THE NORTH-EASTERN MARGIN OF TIBET PLATEAU WITH FREQUENCY-DEPENDENCE OF RECEIVER FUNCTION

作　　者：宋婷 沈旭章 梅秀苹 焦煜媛 李敏娟 苏小芸 季婉婧 SONG Ting;SHEN Xu-zhang;MEI Xiu-ping;JIAO Yu-yuan;LI Min-juan;SU Xiao-yun;JI Wan-jing(Lanzhou Institute of Geotechnique and Earthquake,China Earthquake Administration,Lanzhou 730000,China;Gansu Lanzhou Geophysics National Observation and Research Station,Lanzhou 730000,China;School of Earth Sciences and Engineering,Sun Yat-sen University,Guangzhou 510275,China;Gansu Earthquake Agency,Lanzhou 730000,China)

机构地区：[1]中国地震局兰州岩土地震研究所,兰州730000 [2]甘肃兰州地球物理国家野外科学观测研究站,兰州730000 [3]中山大学地球科学与工程学院,广州510275 [4]甘肃省地震局,兰州730000

出　　处：《地震地质》2022年第5期1290-1312,共23页Seismology and Geology

基　　金：甘肃省地震局(中国地震局兰州地震研究所)地震科技发展基金(2019Q06);国家自然科学基金(41874052,41730212);广东省防震减灾协同创新中心(2018B020207011);国家重点研发计划项目(2017YFC1500103);广东省引进人才创业创新团队(2017ZT07Z066);甘肃省科技重大专项(21ZD4FA011)共同资助。

摘　　要：文中基于青藏高原东北缘甘肃东南部地区70个高密度野外流动观测台阵记录的2a内的远震数据,计算并分别分析单个台站以及沿剖面叠加的接收函数频率特征(高频接收函数莫霍面Ps转换波和多次波多峰值现象),并通过观测和理论接收函数拟合构建了研究区下方莫霍面的S波速度结构。结果表明,研究区内莫霍面相关的接收函数频率特征多样,在绝大多数断裂带两侧具有明显不同的频率特征,反映了研究区壳幔过渡带结构的复杂性和非均匀性。由构建的S波速度结构可知,研究区域的莫霍面并非简单的一级速度界面,而是波速随深度增加而增大的过渡带,意味着研究区下方的地壳具有高黏滞性,不利于下地壳物质的流动,并可据此推断壳幔边界可能存在一些镁铁质物质。而该区域地壳与地幔之间这种复杂的过渡带特征可能是上地幔热物质上涌和底侵作用所致。The northeastern margin of Tibet Plateau is the frontier area where the Tibet Plateau expands and grows towards the interior of the continent.This area is located at the junction of the Tibet Plateau,Ordos and South China blocks.It is also located in the north central section of the north-south seismic belt,the east-west boundary of the Chinese mainland.A variety of structural factors cause dramatic changes in the depth of Moho in the region,and the structural relationship is complex.Many large active faults such as the East Kunlun Fault,the northern margin fault of the West Qinling Mountains,and the Haiyuan-Qilian Mountains Fault have developed.Understanding how the plateau expands in the northeastern margin will help to reveal the mystery of the deformation mechanism of Tibet Plateau.In order to better understand the coupling relationship of fault systems and regional tectonic evolution in the northeastern margin of Tibet Plateau,it’s necessary to explore its crust-mantle transition zone.The material and energy of crust and mantle are constantly differentiated and exchanged in Moho discontinuity,accompanied by a series of geological evolution.Therefore,detecting the thickness and complexity of the crust-mantle transition zone can provide major information for the material and energy exchange,rock phase transformation and component changes of the crust mantle,and help to further reveal the regional geodynamic process.In this paper,the waveforms of earthquakes from November 1,2009 to November 30,2011 recorded by 70 high-density temporary seismic stations in southeastern Gansu Province in the northeastern margin of the Tibet Plateau are used.Teleseismic waveform records with epicenter distance of 30°~90°and surface wave magnitude greater than or equal to 5.5 are selected.Using time-domain iterative deconvolution method,receiver functions of selected data are calculated.Then,by changing the value of Gaussian filter factor in deconvolution,we get receiver functions of different frequency.By analyzing each statio

关 键 词：接收函数 频率特征 青藏高原东北缘 莫霍面 

分 类 号：P315.2[天文地球—地震学]