An Experimental Study On The Minerogenesis Of The Copper Deposits Related To The Emeishan Basalt In The Southwestern Guizhou Province, China

At present, copper is a badly insufficient metal resource in our country. Therefore, it is our geologic workers' important mission to study on the ore-forming mechanism and to prospect for the base of the copper deposits. Taking examples of the Bingba and Heiniuping copper deposits occurring on the contact zone between the base of the Emeishan basalt and limestone of the Middle Permian Maokou Formation in Guizhou province, the paper discussed the geological conditions of basalt-type copper deposits, and some leaching experimental studies of copper in basalt under the Supergene system were carried out:1. Based on the geochemical characters of element copper, it has been revealed that Cu is a kind of sulphophile chemical element. Cu²⁺ is easily mobilized, transported and precipitated under leaching action, because of its strong polarization.2. The copper deposits in western of Guizhou, which were discovered during the early 2000s, are an new type of copper ore deposits occurring in the Emeishan basalt. On the basis of field investigation, mineral assemblages and occurrence modes of ores, two types of the copper mineralization are identified. One is the tuffaceous breccia chalcopyrite mineralization, and another is the secondary native copper mineralization and sulfide mineralization. Among these two types of copper mineralization, the latter is much wider distributed in the border area. The author's studies suggest that this new type of copper ore deposits is very likely to be of important significance in the innovative research and prospecting work.3. Weathering-leaching simulating experiments are carried out on samples of wall rock from the Bingham and the Heiniuping copper deposit, southwestern guizhou, with the aim of determining the relationship between coppery of the Emeishan Basalt and the copper deposits, and determining the optimum physical and chemical conditions for the mobilization of copper in solution. The experimental results show that acidic water is most favorable to the formation of ore-forming element-rich solutions. In addition, the results indicate that copper is most easily mobilized from the Emeishan Basalt if fluids contain chlorine.