粤东连平—河源—汕尾地震测深剖面地壳速度结构及其意义  

Fine crustal velocity structure revealed by a deep seismic sounding profile of Lianping-Heyuan-Shanwei in the Eastern Guangdong

作　　者：叶秀薇[1] 吕作勇[1] 王亮 宋佳佳 段永红[2] 王帅军[2] 宋向辉[2] 郑金宝 皮伟 YE XiuWei;LÜZuoYong;WANG Liang;SONG JiaJia;DUAN YongHong;WANG ShuaiJun;SONG XiangHui;ZHENG JinBao;PI Wei(Guangdong Earthquake Agency(China Earthquake Administration Key Laboratory of Earthquake Monitoring and Disaster Mitigation Technology,Guangdong Provincial Key Laboratory of Earthquake Early Warning and Safety Diagnosis of Major Projects),Guangzhou 510070,China;Geophysical Exploration Center,China Earthquake Administration,Zhengzhou 450002,China;Henan Institute of Geophysical Spatial Information,Henan Geological and Geophysical Engineering Technology Research Center,Zhengzhou 450004,China)

机构地区：[1]广东省地震局(中国地震局地震监测与减灾技术重点实验室,广东省地震预警与重大工程安全诊断重点实验室),广州510070 [2]中国地震局地球物理勘探中心,郑州450002 [3]河南省地球物理空间信息研究院,河南省地质物探工程技术研究中心,郑州450004

出　　处：《地球物理学报》2024年第6期2304-2321,共18页Chinese Journal of Geophysics

基　　金：广东省防震减灾现代化试点省建设项目(2060104);广东省科技计划项目(2018B020207011);国家自然科学基金广东联合基金(U1901602)共同资助.

摘　　要：为适应防灾减灾工作的需要,广东省地震局联合中国地震局地球物理勘探中心、河南省地球物理空间信息研究院于2021年在粤东地区实施了人工地震宽角反射/折射探测,以期获得粤东地区深部地壳速度结构.本文采用地震射线走时正演对粤东地区NW向连平—河源—海丰测线数据进行了处理解释,构建了该剖面的二维壳幔速度结构模型.该模型表明,沿剖面自NW向SE,莫霍面深度由32 km缓慢抬升至29 km,广州—恩平断裂带、河源—邵武断裂带和政和—大埔断裂带的对应位置都显示莫霍面有抬升现象;研究区存在多条NE向展布深大断裂;中地壳发育低速异常区域(低速体)受断裂控制,主要分布于政和—大埔断裂带NW内陆方向,可能与中生代早期岩浆活动形成的花岗岩质岩浆相关.我们认为壳内低速区域(低速体)可能是影响研究区深部孕震环境的重要因素.To meet the needs for the prevention and mitigation of natural disasters,artificial seismic wide-angle reflection/refraction detection was performed by the Guangdong Earthquake Agency,the Geophysical Exploration Center,China Earthquake Administration and Henan Institute of Geophysical Space Information to investigate the crustal structure and tectonic attributes of the deep crust in the Eastern Guangdong.In this paper,data processing and interpretation was conducted using ray tracing and travel-time simulation method for the Lianping-Heyuan-Haifeng survey lines with NW direction of Eastern Guangdong.The two-dimensional crust-mantle velocity structure model of this section was constructed by seismic ray traveltime forward method.The results show that along the section,the depth of the Moho surface gradually decreases from 32 km to 29 km.The elevation of Moho surface was observed in the corresponding positions of Guangzhou-Enping fault zone,Heyuan-Shaowu fault zone and Zhenghe-Dapu fault zone.Many NE trending deep faults were developed in the study area.The low-velocity abnormal areas(low-velocity bodies),controlled by faults,are developed in the middle crust and mainly distributed in the NW inland direction of the Zhenghe-Dapu fault zone.Their formation may be related to the granitic magma formed by the magmatic activities during the early Mesozoic.Therefore,we proposed that the low velocity region(low velocity body)in the crust may be an important factor affecting the deep seismogenic environment in the study area.

关 键 词：华南大陆 粤东地区 人工地震测深 壳幔精细速度结构 壳内低速体 

分 类 号：P313[天文地球—固体地球物理学] P315[天文地球—地球物理学]