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

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...

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

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 bulk V_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 in this area.