长江中下游地区铜地球化学块体物质来源及其对铜矿集区形成的制约

Origin of Cu Geochemical Deomains in the Middle-Lower Yangtze River Region and Its Constraints on the Formation of Cu Deposit Districts

本文从成矿物质供应角度入手,来剖析长江中下游地区大型矿床/矿集区的成因。研究区内共圈定出5个Cu地球化学块体,区内所有已发现的Cu矿集区和绝大多数已发现的大型Cu矿均位于Cu地球化学块体范围内。根据前人获得的研究区典型成矿岩体的Sr-Nd、Hf同位素及成矿岩体中继承锆石年龄,推断研究区产出有矿集区中Cu地球化学块体内巨量的Cu元素主要来源于富集岩石圈地幔,并有少量地壳物质的贡献。正是由于长江中下游地区存在规模巨大的Cu地球化学块体,这些块体能够提供区域成矿带所需的巨量的成矿物质,从而使得该区经历了长期的构造活动、岩浆作用和成矿作用后形成了数量众多的铜矿床。

In this paper,we analyze the genesisof large deposits/ore districts in the Middle-Lower Yangtze River region from the originof ore materials. Five copper geochemical domains in the study area were selected.All discovered Cu deposit concentration areasand most of the large Cu deposits are located within such geochemical domains. Combined with published Sr-Nd,Hf isotopeand zircons U-Pb age data of ore-forming rocks in the study area,we conclude that the large amount of Cu in the region was mainly derived from the enriched lithospheric mantle and a small amount addition of crustal material. These large-scale Cu rich domains can provide huge ore-forming materials for the Middle-Lower Yangtze River metallogenic belt,formingextensive copper mineralization after long-term tectonic activity andmagmatism.