Analyzing Of Igneous Rock Assemblage&Mineralization Geological Background Of ChangAn Gold Deposite And Neighborhood In Honghe Area,Yunnan

Yunnan Honghe ChangAn gold deposit and its adjacent area locate in the middle of Jin Ping fault-block belonging to the south of AiLaoshan constructional belt, in which multifarious pyrogenic rocks are extensively developed excluding ultrabasic rock. They have a wide range change in component reflected by silicon dioxide content between 41.12% and 71.67%. According to the result of former age dating, all magmatic rocks almost intruded simultaneously about more or less at 34 Ma, and they appeared as a veined which is small scale that proves magma just needed a short time to get cold and finish its intrusion. All above features are coincident with the wide spectrum dike swarms’ characteristics, or we can say it does.In the Transient process of magma’s rapid up-welling,intrusion and solidification, the component of pyrogenic rock not depends on differentiation and evolution of the parent magma but mainly on the initial magma melting. Most fomer researchers thought they were comagmatic by analyzing their similar model character of the rare earth element distribution, but it is not possible to generate simultaneously such magmatic assemblages with composition diversity from one magmatic chamber and it is not effective and reasonable to explain the wide component range change of the rock in Tong Chang area.The gold mineralization in this area is related to all kinds of pyrogenic rock. And it had been proved the ore-bearing fluid spread widely for geochemical anomaly of gold all over the Tong Chang area which is related closely to the pervasive pyrogenic rock. There is no doubt that the invasion channel of the magma and the sub- fractures nearby provided the thoroughfare channel for the ore- bearing fluid when hydrothermal activity occurred despite lacking of a favorable site just like ChangAn gold deposit.So we can just find many small scale gold deposit but not a giant one any more. Chang An gold deposit is unique for its particularity of ore controlling conditions combination such as complex dike swarms, fault structure and the particular stratigraphic sequence.All in all, magmatic assemblage, as the main parent rock of the ore bodies in this area feature the WSDS characteristic, it directly indicates the crust delamination effect and extensional structure settings of lithosphere. ChangAn gold deposit, also TongChang Cu- Mo deposit both formed in this kind of tectonic setting.