大型金矿构造-成矿系统及幔-壳多层循环体成因模式-以吉林夹皮沟金矿为例

基于目前代表性金矿成因模式的局限性,以吉林夹皮沟金矿为例把金矿的形成总结为定位、流体、物源、封闭、加热和构造成矿六大系统,建立新的幔-壳多层循环体成因模式:1)以幔源流体、岩浆热液和浅-表部水来源为主,按深、中、浅构成三个层次循环体;2)金质来自多层循环流体对多类型围岩的萃取、沟通混合及多次构造应力共同作用的结果;3)断层泥、迭瓦状构造地质体等可作为成矿封闭屏障;4)中生代(隐伏)花岗岩和各类型脉岩为主要加热热源;5)矿带座落在韧性构造超壳断裂之上及附近,而矿体却主要赋存在脆性构造内,主成矿时代为燕山期,整体受构造-成矿系统控制.该模式对燕山期花岗岩中金矿是一种检验,对其它变质岩区金矿则是一种启迪.

STRUCTURAL-METALLOGENIC SYSTEMS OF LARGE-SCALE GOLD DEPOSIT AND GENETIC MODEL OF MANTLE-CRUST GRADATIONAL CIRCULATORY FLUID

The geneses of gold deposit have been controversial focal points in learning all the time, which deals with a widespread and deepen extent. The genetic studying of gold deposit in the metamorphic rocks has been specially complex. Some metallogenic models of gold deposits, such as metamorphic model, magma model, lamprophyre-earth crust replacement model, etc., are recently represented, and they are not perfect on metallogenic locating, fluid, gold element origin, etc. The paper takes the Jiapigou Gold Deposit in Jilin as an instance and sums up six metallogenic systems, namely, the locating, fluid, material origin, sealing up and structural metallization. A new genetic model of mantle-crust gradational circulatory fluid sets up, with the main points as follows. 1. Tectonites reflect tectonic framework in the area. Sliding between the earth crust and mantle, continental tension fracture and uplift bedding-delamination structure result in poly-type tectonites. The poly-type tectonites constitute three gradations individually, which are ore-controlling structures for the deep, middle and shallow levels respectively. 2. Metallogenic fluids mainly come from mantle, magma and ground water. The fluids constitute three gradational circulatory fluids, which correspond, from mantle to earth crust, with the C-H-O-rich fluid in the deep level, the Si-bearing fluid in the middle level and the S-bearing fluid in the shallow level. 3. Instead of coming from a kind of lithological unit, gold element is a product that poly-gradational circulatory fluids draw country rocks, join together and mix each other. Also, it is a result of poly-structural mechanisms, for example, tectonic heating, tectonic deformation, tectonic fluid, tectonic pressure reduction and tectonic coupling. 4. Deep-sea water column, fault clay, imbricate structure and geological bodies of nappe-outlier make up metallogenic sealing up barrier. 5. The Mesozoic granites or concealed granites and vein rocks are in action in heating origin. 6. Gold deposit belt is located in ductile structure near super-crust fault, but there are ore bodies in brittle structure. The main minerogenetic epoch determined is in the Yanshanian orogeny. Structural metallogenic systems control gold deposit as a whole. The structural metallogenic systems can be divided into three types: the tectono-ore-forming system in the divergent continental margin, the tectono-ore-forming system in the convergent continental margin, and the tectono-ore-forming system in the strike-slipped continental margin. The model may be a verifying for the gold deposit in the Yanshanian granites and an elicitation for gold deposit in other metamorphic rocks.