钦杭何在？来自综合地球物理探测的认识

Where is Qinzhou-Hangzhou juncture belt? Evidence from integrated geophysical exploration

扬子古板块与华夏古板块的结合带(简称钦杭结合带)是中国东南部一条最重要的构造岩浆成矿带,其西段的位置和边界的划分方法,尚存在较大的争议。本文以大尺度卫星重磁资料为主,结合区域电性和地震资料的综合处理和分析,对钦杭结合带的边界进行了识别和厘定。研究认为,钦杭结合带是江南造山带的南部边界,结合带南界为宁波-金华-上饶南-赣州北-郴州-北海东,北界为上海-湖州-鹰潭-临川-萍乡-衡阳-永州-桂林-梧州-钦州。在结合带两侧,无论是重力场还是磁力场都具有明显不同的特征,反映了扬子和华夏板块不同的物质组成和基底特征。钦杭结合带内地球物理场也存在局部差异,揭示了结合带经过多期次岩浆活动,在不同地段形成了不同组合的金属矿床和别具特色的钦杭成矿带。

The suture zone between the Yangtze Paleoplate and the Cathaysia Paleoplate(called Qin-Hang junction belt) is one of the most important tectonic-magmatic-metallogenic belts in southeastern China. There is still considerable controversy over the method of dividing the location and boundary of the western section of the Qin-Hang junction belt. In order to identify and determine the boundaries of the Qin-Hang junction belt, the authors employed the large-scale satellite gravity and magnetic data in combination with the integrated processing and analysis of regional magnetotelluric and broadband seismic data. The comprehensive evaluation shows that the Qin-Hang junction belt is the southern boundary of the Jiangnan orogenic belt. The authors hold that the border is Ningbo-Jinhua-Shangrao-Ganzhou-Chenzhou-Beihai in the south and Shanghai-Huzhou-Yingtan-LinchuanPingxiang-Hengyang-Yongzhou-Guilin-Wuzhou-Qinzhou in the north. On both sides of the joint belt, both the gravity field and the magnetic field have distinct characteristics, indicating the different material compositions and basements between the Yangtze and Cathaysia plates. There are also local differences in the geophysical fields of the Qin-Hang junction belt, suggesting that the tectonic belt has undergone multiple stage magmatism and formed different combinations of metal deposits in different sections,forming a unique metallogenic belt, i.e., the Qin-Hang metallogenic belt.