利用接收函数H-κ-c叠加方法约束武陵山重力梯度带地壳结构  

Constraining the crustal structure of the southern segment of the north-south gravity lineament by the receiver function H-κ-c method

作　　者：穆青 黄荣[2,3] 严加永[1] 卢占武[4] 罗银河[2,3] 张永谦[1] 姜小欢 文宏斌 魏鹏龙 周万里 MU Qing;HUANG Rong;YAN Jiayong;LU Zhanwu;LUO Yinhe;ZHANG Yongqian;JIANG Xiaohuan;WEN Hongbin;WEI Penglong;ZHOU Wanli(SinoProbe Laboratory of Ministry of Natural Resources,Chinese Academy of Geological Sciences,Beijing 100037,China;School of Geophysics and Geomatics,China University of Geosciences(Wuhan),Wuhan 430074,China;State Key Laboratory of Geological Processes and Mineral Resources,China University of Geosciences(Wuhan),Wuhan 430074,China;Institute of Geology,Chinese Academy of Geological Sciences,Beijing 100037,China;School of Civil Engineering and Architecture,Wuhan Polytechnic University,Wuhan 430023,China;State Key Laboratory of Geodesy and Earth’s Dynamics,Innovation Academy for Precision Measurement Science and Technology,Chinese Academy of Sciences,Wuhan 430077,China)

机构地区：[1]中国地质科学院自然资源部深地科学与探测技术实验室,北京100037 [2]中国地质大学(武汉)地球物理与空间信息学院,湖北武汉430074 [3]中国地质大学(武汉)地质过程与矿产资源国家重点实验室,湖北武汉430074 [4]中国地质科学院地质研究所,北京100037 [5]武汉轻工大学土木工程与建筑学院,湖北武汉430023 [6]中国科学院精密测量科学与技术创新研究院大地测量与地球动力学国家重点实验室,湖北武汉430077

出　　处：《地学前缘》2023年第5期369-383,共15页Earth Science Frontiers

基　　金：自然资源部深地科学与探测技术实验室开放课题(Sinoprobe Lab:202206);地质过程与矿产资源国家重点实验室科技部专项(MSFGPMR2022-4);大地测量与地球动力学国家重点实验室2022年基金项目(SKLGED2022-4-2);湖北巴东地质灾害国家野外科学观测研究站开放基金项目(BNORSG-202214)。

摘　　要：贯穿中国内地南北的大兴安岭-太行山-武陵山重力异常梯度带被认为是东亚重要的岩石圈分界线,本文利用布设在武陵山重力梯度带的43个国家地震局固定台站和10个流动宽频台站的观测数据,采用远震P波接收函数方法,计算并挑选了共计12 739条高质量的远震P波接收函数,综合其中7个台站H-κ叠加和46个台站H-κ-c叠加的结果,并结合前人结果获得了研究区的莫霍(Moho)界面起伏形态以及地壳平均波速比(v_(P)/v_(S))分布和通过H-κ-c叠加方法获得相应台站下方地壳各向异性。结果表明研究区地壳厚度在30~52 km之间,其中最厚的大巴山区域超过50 km,最薄的雪峰山以东地区仅约30 km,整体特征表现为西厚东薄。Moho界面梯度变化最大的区域,北起秦岭-大巴山东侧一带,沿着江汉盆地与武陵隆起的盆山耦合处,南至江南造山带中段北侧;地壳平均波速比整体的分布特点表现为:高值(>1.81)普遍分布在武陵山重力梯度带以西地区,而低值(<1.75)分布以东地区以及江南造山带内部;地壳各向异性同样在武陵山重力梯度带两侧存在明显差异,以东地区快波最大极化方向为近E-W向,而以西地区则表现为NE-SW向。最后,我们推测武陵山重力梯度带附近及以东地区存在普遍的下地壳拆沉现象。The north-south-oriented Daxing’an-Taihangshan-Wulingshan Gravity Lineament,which is across the whole China's Mainland is considered the most important intra-continental gravity gradient belt in East China.Data used in this study were from 43 permanent and 10 portable broadband seismic stations near the Wulingshan Gravity Lineament.A total of 12739 teleseismic P-wave receiver functions(pRFs)were calculated,and pRFs from 7 and 46 stations were then stacked using respectively the H-κand H-κ-c methods.Combining previous studies,we obtained the lateral variation of the crustal thickness,average crustal v_(P)/v_(S) ratio and crustal anisotropy beneath the study region.The crustal thickness varied greatly,between 3052 km,where the thickest crust was found under the Daba Mountain area and the thinnest to the east of the Xuefeng Mountain.Our results also showed the maximum gradient of the Moho interface traced from the Qinling-Dabashan Mountain in the north along the junction area between the Jianghan Basin and the Wuling uplift,and extended southward to the north of the Jiangnan orogenic belt.The high v_(P)/v_(S) ratio(>1.81)are generally distributed in the area west of the Wulingshan Gravity Lineament,while to the east the v_(P)/v_(S) ratio are lower than(<1.75)and so did the Jiangnan orogenic belt.Similar differences in crustal anisotropy were found between the two sides of the Wulingshan Gravity Lineament,where the fast polarization directions(FPDs)on the east side is nearly E-W while on the west side nearly NE-SW.Finally,we inferred a common occurrence of lower crustal delamination near the Wulingshan Gravity Lineament and areas to the east.

关 键 词：武陵山重力梯度带 接收函数 H-κ-c叠加 地壳结构 

分 类 号：P315.2[天文地球—地震学]