Assessment Of Lead-Zinc In Western Hunan-Western Hubei Area, China

The region of West Hu’nan-Hubei is one of sixteen metallogenic provinces (belts) ascertained by "Decision on strengthening geological work announced by the State Council". The main characteristic of Pb-Zn deposits in this region is low-grade and large-tonnage and the perspective resources storages are more than 1500 myriad tons. Bingdongshan, Aozigang Zn deposits in Hubei, and Limei Pb-Zn deposit in Hu’nan have been chosen to study in detail and important achievements are as follows.1. Based on studying above three deposits and summarizing stratigraphic, lithologic, paleogeographic, tectonic, magmatic, metallogenic characteristics, Pb-Zn deposits in this region are attributed to "Yangtze-type". Characteristics of above stratified and stratoid Pb-Zn deposits located in early-Paleozoic marine carbonatite around the Yangtze platform are low-grade and large-tonnage.2. The epigenetic "Yangtze-type" Pb-Zn deposits are influenced by tectonic activities around Southeast rim of the Yangtze platform. Main metallogenesis is depositing-reworking and hydrothermal metamorphism, but biogenic sediment and ancient karstification are also significant in some deposits. The depositing-reworking effects become weaker from metamorphic basal swelling to faraway place. S and Pb isotopic compositions show majority of Pb and Zn elements mainly come from marine carbonatite strata (Sinian (Neoproterozoic)-Permian), but minority come from metamorphosed basement.3. Multiple ore-controlling factors of "Yangtze-type" Pb-Zn deposits have been systematically, including strata, lithofacies, paleogeography and structure. Direct and indirect indicators have been provided, including strata, lithologic characters, structures, mineralized outcrops, geochemical abnormalities, geophysical abnormalities and terrains. These indicators are important guides to explore this kind of Pb-Zn deposits.4. Take Bingdongshan Pb-Zn deposit as an example, this paper assesses economical significance and establishes model of "Yangtze-type" Pb-Zn deposits in West Hu’nan and West Hubei provinces. According to internal earning rate (13.38%), financial net present value investment (-56.08 million RMB) and project payback period (9.3 years), the mining-concentrating project is infeasible at present. And sensitivity analysis has been done from some aspects of investment in fixed assets, operating costs, Pb-Zn metal prices, Pb-Zn ore grades, comprehensive recovery of associated resources. Assessment and exploration of high-grade resources should be carried out at beneficial positions of this deposit.5. On the basis of above assessment and analysis, this paper provides that five Pb-Zn prospect areas, including East Dabashan, Shennongjia-Huangling in Hubei, Hefeng in Hubei-Longshan in Hu’nan, Zhangjiajie in Hu’nan-Tongren in Guizhou and Yuanling-Huaihua in Hu’nan. Combining with actual works, we suggest that geological prospecting workings on "Yangtze-type" Pb-Zn deposits will be made great breakthroughs by depending on two national documents "Engineering Geology and Mineral Resources Protection" and "Geological Prospecting New Mechanism" in order to releasing Pb-Zn raw material supply, quickening local economy, promoting labor employment and social stability.