大陆再造与钦杭带北东段多期铜金成矿作用  

Multiple episodes of Cu-Au mineralization in the northeastern section of the Qin-Hang metallogenic belt induced by reworking of continental crust

作　　者：倪培[1] 王国光[1] 

机构地区：[1]南京大学内生金属矿床成矿机制研究国家重点实验室地质流体研究所地球科学与工程学院,南京210023

出　　处：《岩石学报》2017年第11期3373-3394,共22页Acta Petrologica Sinica

基　　金：国家重点研发计划(2016YFC0600206;2016YFC0600205);全国危机矿山项目(20089935)联合资助

摘　　要：大陆再造与铜金成矿系统的研究是当前国际矿床学前沿领域。钦杭成矿带是我国21个重点成矿区带之一,也是扬子与华夏地块的拼贴带。近年,对钦杭带北东段一系列铜金矿床的系统研究表明,成矿作用与富铜金大陆地壳形成和随后的多期再造过程密切相关。晚中元古代-早新元古代,在被动大陆边缘的伸展环境,软流圈地幔部分熔融形成铁砂街岩群细碧岩和VMS型铁砂街铜矿。之后新元古代的洋壳俯冲,岛弧环境的俯冲板片部分熔融形成双溪坞岩群岛弧火山岩和VMS型平水矿铜矿体,其成矿流体主要来自于深循环海水,成矿物质主要来自于平水组幔源火山岩。随后发生的扬子与华夏地块的陆陆碰撞造山作用,新元古代双桥山群基底地层发生强烈再造,形成了受韧性剪切带控制的金山造山型金矿,富CO2变质流体的不混溶作用是金富集沉淀的最重要机制。早古生代,华南陆内造山作用导致新元古代双溪坞岩群和陈蔡岩群发生再造,形成了早古生代韧性剪切带及相应的造山型金矿(璜山、平水金矿等),金的富集沉淀与富CO2变质流体的演化密切相关。韧性剪切带及特征的富CO2变质流体,可以作为加里东期造山型金矿的找矿标志。晚中生代,古太平洋板块开始向华南大陆东南缘俯冲,位于华南内陆的德兴地区受到俯冲作用远程效应,导致德兴地区新元古代富铜金新生地壳部分熔融,形成低镁埃达克质岩及与其相关的银山和建德铜金多金属矿床,当部分熔融过程受到岩石圈地幔影响,则形成高镁埃达克质花岗闪长斑岩及超大型德兴斑岩铜矿。因此,钦杭成矿带北东段先后发生晚中元古-新元古代、早古生代和晚中生代多期铜金成矿。新元古代江南造山事件和稍早的板内岩浆作用形成了富铜金的新生地壳,为钦杭带北东段多期铜金成矿作用以及燕山期金属巨量堆积奠定了丰厚的物The relationships between growth and reworking of continental crust and Cu-Au mineral systems are hot topics among economic geologists. The Qin-Hang metallogenic belt is one of twenty-one important metallogenic belts in China and is located along the suture zone between the Yangtze and Cathaysia blocks. In recent years, the systematic studies on a group of Cu-Au deposits in the northeastern section of the Qin-Hang metallogenic belt indicate that the mineralization shows close links with the multiple episodes of reworking of continental crust. During Late Mesoproterozoic to Early Neoproterozoic, they were most probably derived from the asthenospherie mantle in an intra-plate extensional setting along the passive continental margin. Meanwhile, the Tieshajie VMS type Cu deposit was generated and was hosted in the Tieshajie Group basalts. During the Neoproterozoie oceanic subduction, partial melting of subducted slab caused the formation of the Shuangxiwu are volcanics and the VMS type Pingshui Cu deposit. The ore fluids of this deposit were derived from the deeply circulated seawater and the metal primarily came from the mantle-derived Shuangxiwu volcanics. Subsequently, the collision between the Yangtze and Cathaysia blocks resulted in the strong deformation of basement strata of the Neoproterozoic Shuangqiaoshan Group, and the generation of the ductile shear zone hosted Jinshan orogenic gold deposit. During the Early Paleozoic, the intra-eontinental orogeny in South China lead to the reworking of the Neoproterozoic Shuangxiwu and Chencai groups and formed an orogenic gold belt, including Huangshan and Pingshui gold deposits, along the eastern section of the Jiang-Shao fauh zone. During the Middle Jurassic, the paleo-Pacific plate initially subducted towards northwest along the southeastern margin of South China. In response to the far-field effects of the subduction, the remelting of Neoproterozoic metal-rich juvenile lower crust and subcontinental mantle lithosphere formed the high-Mg Dexing granodiorites and the

关 键 词：铜金成矿 大陆再造 江南造山事件 钦杭成矿带 

分 类 号：P611[天文地球—矿床学]