Metallogenic Regularity And Prospecting Prediction Of Manganggang Gold Deposit In Yunnan Province

Shangmanggang gold deposit is located in the Southwestern part of transition zone between Sanjiang tectonic belt and India-Gaoligong mountains metamorphic edge, the gold deposit is in the south Longling-Ruili major fault and on the east side of the north east to subprime Shangmanggang fracture, the area belongs to the tectonics-magma-metamorphic-metallogenic belt of Gaoligong mountains, the known gold mineralization is controlled by Shangmanggang fault fracture zone and unconformity surface and the ancient karst surface. The deposit is the first carlin type gold deposits in western Yunnan. Basic geological research of the deposit is still relatively weak, The periphery prospecting direction is not clear, gold resources are scarce in recent years, theoretical guidance and metallogenic regularity is necessary for system research.On the basis of a large number of field work, the paper made the analysis of regional geological background, structural geology, petrology, mineralogy, ore deposits, geochemistry and isotope geology and other multi-disciplinary theories and methods are applied, the geological characteristics, ore genesis and ore-controlling factors of Shangmanggang gold ore deposit are made for comprehensive analysis and research, the paper summarizes the metallogenic regularities and metallogenic model, and it determined the ore-prospecting criteria, five prospecting prospect areas is proposed, and it has been verified by exploration engineering.This study achieved the following conclusion:(1) Shangmanggang gold deposit is in LuXi gold metallogenic belt which is a secondary unit in Longling-Ruili fault zone, it belongs to extend structural conversion area. Gold deposits distribute along the northeast-southwest direction, strictly controlled by Shangmanggang fracture, the upper wall is Mengga group and the footwall slope is Shazipo group, the Shangmanggang deposit includs red clay type gold oxidized ore on the surface and native sulfide ore underground.(2) the red clay layer thickness of Shangmanggang gold on the surface is different, oxidation type ore body cover on the original carlin type ore body, the section of red clay provides significant zonality, the laterization is immature, it contact with native carlin type ore bodies in lower part, the genesis of red clay type ore body and original carlin type ore is closely related, red clay type ore body is the production of native card cover type ore body with the help of a series of supergene action (especially the laterization).(3) The ore type of Shangmanggang deposit is mainly divided into red clay, clay sand-siliceous clastic rock type and altered cataclastic-breccia dolostone type. Mineral composition is complicated, mainly composed of a variety of native residual minerals and hypergenic minerals, ore structure is also complicated, wall rock alteration is obvious, it is similar to the carlin type gold deposits, mineralized alteration is limited to fault fracture zone and adjacent area, from fractured zone to the outside, it can be roughly divided into silicified belt, clay-silicified belt and clay belt.(4) geochemical characteristics of trace elements and rare earth elements shows that the the red clay type gold deposit originated from the carlin type gold deposits, Shangmanggang geological and geochemical features are similar with the United States carlin type gold deposits, the fluid inclusion analysis show that the gold deposit formed in meso-low temperature, sulfur isotope analysis indicates that Shangmanggang gold sulfur may have derived from magma mixed with marine sulfate or sea water, hydrogen and oxygen isotopic compositions is similar with magmatic water, may be from hydrothermal alteration, lead isotope analysis results show that Shangmanggang gold ore source may from lower crust or from upper mantle blended with a large number of crust material.(5) Shangmanggang gold mine is essentially the production of crust tension which lead to mantle material upwelling caused a series of geological processes, the element Au is activatied and migrate and accumulated, it can be summarized as:the late Indosinian-Yanshanian period, the expansion of marginal sea sedimented Mengga formation, it provides the foundation for the construction of the elements such as Au; Late yanshanian-Himalayan period, tectonic-magmatic-thermal fluid system formed, hydrothermal mineralization happened in shallow area; meso-low temperature alteration and mineralization around fracture system development; After the formation of deposit, shallow orebodies are transformed by karstification, residual action and laterization, finally red clay type gold ore bodies formed which is controlled by the fault fracture zone and unconformity surface and ancient karst surface.(6) the ore-prospecting criteria is summarized as tectonic marks, strata marks, hydrothermal alteration, mineral, red clay layer marks, geomorphic marks, five metallogenic prospect areas are delineated:deep area of Shangmanggang gold mining area, Mengmo-Xiabashan area, Huilong Village-Xiangqiu area, Hebianzhai area and Mabozi area, three prospecting target is preferred, recently, marked prospecting fruits have been achieved by exploration projects.