短周期线性密集台阵揭示的粤东地区地壳结构特征  

Crustal Structure Characteristics Revealed by Short-Period Linear Dense Array in Eastern Guangdong

作　　者：张雪莹 段永红[1] 王帅军[1] 宋向辉[1,2] 高占永 王亮 宋佳佳 ZHANG Xueying;DUAN Yonghong;WANG Shuaijun;SONG Xianghui;GAO Zhanyong;WANG Liang;SONG Jiajia(Geophysical Exploration Center,CEA,Zhengzhou 450002,China;School of Earth Sciences and Resources,China University of Geosciences,Beijing 100083,China)

机构地区：[1]中国地震局地球物理勘探中心,郑州市450002 [2]中国地质大学(北京)地球科学与资源学院,北京市100083

出　　处：《大地测量与地球动力学》2024年第11期1131-1137,共7页Journal of Geodesy and Geodynamics

基　　金：国家自然科学基金(42374073);中国地震局地球物理勘探中心青年项目(YFGEC2023001);河南省自然科学基金(242300421374)。

摘　　要：利用跨江西省、广东省、福建省布设的225个短周期密集台阵观测时长为58d的远震波形数据,采用P波接收函数H-κ扫描叠加和共转换点(CCP)叠加两种方法,对研究区下方地壳厚度、泊松比分布和接收函数成像进行研究。结果表明:1)研究区地壳厚度和泊松比具有明显的分块性,并与断裂分布有关,地壳厚度变化总体上表现为由西北向东南由薄变厚再逐渐减薄的趋势,变化范围为27.1~33.9km,平均地壳厚度为29.9km,且地壳厚度变化与地表起伏符合地壳均衡理论。2)研究区泊松比变化范围为0.21~0.33,平均泊松比为0.26,整条测线泊松比大于0.25的部分占比70.83%,属于高泊松比区域,原因可能为研究区多发育断裂破碎带,俯冲板块物质的深部熔融导致地幔物质沿断裂部分上涌,使得地壳中石英含量减少。3)研究区在距地表10~15km范围内存在一个较为连续的负极性界面,结合前人研究,将其解释为华夏地块东部广泛存在的低速层顶部界面,在距地表15~20km范围内存在地壳低速体,发育位置偏向内陆方向。We use 58 days of teleseismic waveform data collected from 225 short-period dense seismic arrays arranged across Jiangxi,Guangdong,and Fujian provinces,and use P-wave receiver function H-κscanning stack and common conversion point(CCP)stack methods to analyze the crustal thickness,Poisson’s ratio distribution,and receiver function imaging beneath seismic stations in the study area.The results show that:1)The crustal thickness and Poisson’s ratio in the study area exhibit clear block feature,closely related to the distribution of faults.The overall crustal thickness varies from thin to thick and gradually thins from northwest to southeast,with a range of 27.1 to 33.9 km and an average of 29.9 km.The variation of crustal thickness and surface fluctuation are consistent with the crustal isostasy theory.2)The Poisson’s ratio of the study area ranges from 0.21 to 0.33,with an average of 0.26.70.83%of the whole survey line has a Poisson’s ratio greater than 0.25,which belongs to the high Poisson’s ratio area.It may be related to fault fracture zones in the study area.The deep melting of subducted plate materials leads to the upwelling of mantle materials along faults,which reduces the quartz content in the crust.3)In the depth range of 10-15 km from the surface,there exists a relatively continuous negative polarity interface in the study area.Combining with previous studies,we interpret this as the top interface of a widespread low-velocity layer in eastern Cathaysia block.Within the depth range of 15-20 km from the surface,a low-velocity body is present and tends towards the inland direction.

关 键 词：粤东地区 接收函数 短周期线性密集台阵 地壳结构 泊松比 

分 类 号：P313[天文地球—固体地球物理学]