江南造山带中段地壳结构与成矿启示:基于广昌-浏阳剖面接收函数的认识  

Crustal structure of the middle segment of the Jiangnan Orogen and its implications on mineralization:Revealed by teleseismic receiver functions along the Guangchang-Liuyang profile

作　　者：张永谦 吕庆田[1,2] 严加永[1,2] 徐峣[1,2] 林吉焱 皮娇龙[4] 陈淼[1,2] 张文文 ZHANG YongQian;LüQingTian;YAN JiaYong;XU Yao;LIN JiYan;PI JiaoLong;CHEN Miao;ZHANG WenWen(Chinese Academy of Geological Sciences,Beijing 100037,China;China Deep Exploration Center-SinoProbe Center,Chinese Geological Survey&Chinese Academy of Geological Sciences,Beijing 100037,China;Geophysical Exploration Center,China Earthquake Administration,Zhengzhou 450002,China;Institute of Geophysics,China Earthquake Administration,Beijing 100081,China)

机构地区：[1]中国地质科学院,北京100037 [2]中国地质调查局中国地质科学院地球深部探测中心,北京100037 [3]中国地震局地球物理勘探中心,郑州450002 [4]中国地震局地球物理研究所,北京100081

出　　处：《岩石学报》2022年第2期559-572,共14页Acta Petrologica Sinica

基　　金：国家自然科学基金项目(42074099、41574082、41804093);中国地质调查局地质调查项目(DD20190012、DD20221643);国家重点研发计划项目(2016YFC0600201)联合资助.

摘　　要：江南造山带位于华南大陆扬子块体和华夏块体之间,其深部地壳结构与变形特征记录了扬子块体与华夏块体拼合与相互作用的痕迹,且在其内部与邻区发育了丰富的多金属矿床,并形成了巨型Cu-Au-Pb-Zn-Ag多金属成矿带,是深化认识华南大陆地壳演化、岩浆作用与成矿系统的关键地域。针对华南大陆地区的地壳结构与成矿过程,国家科技重点研发计划“华南陆内成矿系统的深部过程与物质响应”项目在该区实施了一条密集宽频带地震流动探测剖面,旨在探测其深部结构与物性变化特征和深部成矿背景。本文利用其中江西广昌-湖南浏阳段长320km的宽频带地震流动台站数据开展了远震P波接收函数研究,获得了剖面辖区深部地壳结构和V_(p)/V_(s)变化特征。研究结果表明:(1)剖面Moho界面深度在29~35km之间变化,呈近穹窿状分布,平均Moho界面深度为31km左右,低于全球大陆地壳平均值,且与地形高程在整体上呈镜像相关,均衡程度较好;(2)剖面沿线地壳V_(p)/V_(s)在1.64~1.83之间呈波浪状起伏变化,平均值为1.72左右,且华夏块体略高于江南造山带地域;(3)赣江断裂下方两侧的地壳厚度和V_(p)/V_(s)均差异明显,表明赣江断裂一处地壳尺度的深大断裂;(4)古太平洋板块俯冲作用并不直接造成江南造山带的地壳变形,但俯冲作用的远程力效应或对该区的地壳演化和成矿作用有间接影响。The Jiangnan Orogen is located between the Yangtze Block and the Cathaysia Block,the central part of the South China continent.Rich polymetallic deposits are developed in its interior and adjacent areas,forming a giant Cu-Au-Pb-Zn-Ag polymetallic metallogenic belt.The crustal structure of the Jiangnan Orogen records the integration and interaction between the Yangtze Block and the Cathaysian Block,and is a key area for further studying the crustal evolution,magmatism and metallogenic system of the South China continent.To reveal the crustal structure and physical properties of the crust in South China,we conducted a dense broad-band seismic survey profile,funded by the National Key Research and Development Program of the“Deep Processes and Material Response of South China Intra-Continental Metallogenic System”.In this paper,we use the teleseismic data of the portable seismic stations along the 320-km-section between Guangchang,in Jiangxi Province and Liuyang,in Hunan Province to study the crustal structure of the Jiangnan Orogen.We apply teleseismic P-wave receiver function method to study the architecture and the bulkV_(p)/V_(s) ratio of the crust beneath the middle section of the Jiangnan Orogen.The results show that:(1)The Moho depth varies in a range of 29~35km,with a dome-shaped distribution.The average depth of Moho is~31km,lower than the average value of the global continental crust,and mirror the topographic elevation well.(2)The crustal bulk V_(p)/V_(s) ratio varies in a range of 1.64~1.83 along the profile,with an average value of~1.72,and is slightly higher in the Cathaysia Block than in the Jiangnan Orogen.(3)The crustal thickness and V_(p)/V_(s) ratio on both sides of the Ganjiang fault are significantly different,indicating that the Ganjiang fault is a crustal scale fault.(4)The subduction of the paleo-Pacific plate may not directly influence the crustal deformation of the middle section of the Jiangnan Orogen.Instead,it may have an indirect influence on the crustal evolution and mineralization

关 键 词：华南大陆 江南造山带 华夏块体 地壳结构 接收函数 

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]