Geology, Geochemistry And Metallogenetic Model Of Copper-polymetallic Deposits In Nameung, Vientiane Province Of Laos

NaMeung mine is located in the intersected area of Luang Prabang and Truongson metallogenic zones. As the most important ore concentration area in Laos, NaMeung is very advantageous in its metallogenic background. On the basis of understanding about the geological background, and the analysis of the mine geological features, studies are carried out about NaMeung mine in copper polymetallic ore-forming laws, the genesis of ore deposits mineralization mode and geochemistry.Within the area, it is notable that the copper polymetallic ore bodies mainly occur in the contact zone between the Yanshanian granite and Carboniferous limestone rocks, and skarn is indicative as the main ore-controlling factors. Ore body have lenticular, irregular pulse and laminated output. Ore minerals have chalcopyrite, magnetite, sphalerite, galena; Gangue minerals are garnet, diopside, epidote, calcite etc. The ore textures have coarse-grained texture, porphyritic texture, metasomatic texture, secondary textures. The ore structures are mainly sparse disseminated-like structure, compact massive structure, and banded structures.Types of the ore deposits in the area are mainly classified as skarn copper-zinc-lead-silver ore deposit and granitic-molybdenum mineralization. The main ore-controlling factors are the granite intrusions and its intruded carbonate host rocks, fractures and contact zones. Mineralization is closely related to the late magmatic hydrothermal process and in space related with the granite porphyry intrusion. The late magmatic hydrothermal fliud is emplaced along the EW tectonic fractures or tensile fault zones, due to its implacement into different geological body and thus forms the different types of mineralization.Stream sediments and secondary halo geochemistry shows that Cu is the main ore-forming element, Ag, Pb, Zn, and Bi, W are favorable elements to mineralization, background value of Au, Ag, and Cu in Carboniferous limestone, Jurassic siltstone, shale and mudstone is high and locally enriched. Geochemical characteristics of copper and silver polymetallic ore bodies are in consistent with the characteristics of low-temperature ore-forming element combination. Seven combination anomalies are identified on the basis of the geochemical survey, among the anomalies, we have1st priority anomalies3;2nd priority anomalies2;3rd priority anomalies2; the shapes of the anomalies, the trend and scale of the anomalies are consistent with the exposed alteration zone, mineralization zone, intrusive contact zone in the area.