Geological Features of Ore Deposit and Diagenetic and Metallogenic Model of the Hadamengou Gold Ore Field in Inner Mongolia

Gold-mineralized bodies of the Hadamengou Gold Ore Field in Inner Mongolia have five main forms:they are potassic feldspar vein type, quartz vein type, two veins type, quartz-potassic feldspar vein type and altered gneiss type. There are four types of ore in this area:potassic feldspar vein type ore, quartz vein type ore, quartz-potassic feldspar veins type ore and altered rock type ore. The wall rock alteration and mineralization include pyritization, brass mineralization, galena mineralization, potassic, silicification, chloritization, epidotization, sericitization and carbonation, etc. Alteration phase are divided into inside and out alteration. Inside alteration zone consists of potassic and silicification and out lteration zone consists of chloritization, epidotization and sericitization. Carbonation exists through out gold mineralized bodies. The five main forms of gold-mineralized bodies, the four types of ore and the zoning of the wall rock alteration, mutual interpretate and correspond to each other. The gold content are higher in the regular two walls of Potassic feldspar vein type gold-mineralized bodies and in the quartz vein type gold-mineralized bodies than in those of the middle part. Mineralized-bodies have different gold content; quartz-potassic feldspar vein type gold-mineralized bodies have the highest gold content. Ore types in single gold mineralized body have the characteristics of diversity and complexity. The zoning property of the wall rock alteration can be divided into inside alteration zone and out alteration zone. These all prove the correctness of the theory of magmatic conduit metallogenic system, in which ore forms in the process of the intrusion of the potassic feldspar vein, the quartz vein and the gold-bearing fluid flow. Based on the magmatic conduit metallogenic theory, the authors infer a diagenetic and metallogenic model of gold ore field. Regional metamorphism occurred after the gneiss diagenesis, forming structural weak zone; under the tectonic tensile stress, potassic feldspar veins formed with the potassic magma intrusion, and later quartz veins formed with siliceous magma intrusion; thus magmatic conduit system formed. The space occupied by mineralized potassic feldspar vein, mineralized quartz vein, gold-bearing fluid flow, including the space occupied by mineralized and altered gneiss, is both the magmatic conduit metallogenic system and ore-holding space. The geological features of ore deposit and the diagenetic and metallogenic model of the Hadamengou gold ore field have great significance for the surface and deep prospecting and the confidence of mine prospecting and production.