Small Artesian Basin In Western Yunnan Leachable Sandstone Uranium Mineralization Conditions And Long-term Forecasts

Work region located in the area of the Cenozoic Era basin of continental borderland in Tengchong acting zone, situated in Zang-Dian middle plate between Indian plate and Huanan plate. This region is formed by basement structure system, the Palaeozoic Era structure system and the Cenozoic Era system through more times of geological evolution, and occured frequent Intermediate-Acidic magmatic acticities in Yanshan-Himalayan period as Indian plate moved northward, magmatites are mainly basement of the Cenozoic basin.Basement magmatites are divided into two type:1)crustal remelting magatite and 2)migmatitic magatite in this report. The latter type can be divide into potassic migmtitic magmatite and sodic migmatitic magmatite. The Cenozoic Era basin can be divided into eastern basin,western basin and middle basin according to characteristic of distribution. In work region, eastern basin, western basin and north-east of middle basin are favorable place for mineralization, and crustal remelting magmatite or potassic migmatitic magmatite is favorable basement for mineralization..In this report structure evolution of Longchuanjiang basin is divided into four stage, and indicate that mineralzation is closely related to two stratigraphic gap in the process of structure evolution, one between N_m1¹ and N₂m₁², the orther between N₂Im₁² and N₂m₁³.This report give a brief account of uranium mineralization for western of Yunnan province, interpret the mainly characteristic of uranium mineralization in sandstone of Longchunjiang basin, and analyse the age of three ore sample's rock time line from 382 deposit, the result is 5Ma, 1.2Ma and 0.5Ma.In this region, exist modern hydrologic-geochemical zone and ancient hydrolodic- geochemical zone which controlled mineralized area, the latter zone formed by strata water and threatic water. And exist ancient oxygenous threatic zone and ancient phreatic water developed zone, as new understand , these two zone are very important for controlled factor of mineralization.There are many and varied kind of mineralization in this region , such as surface lithogenetic mineralization, ancient phreatic mineralization, strata bearing water and hot water mineralization, and terrestrial heat flow mineralization. Through analysis of mineralized factor, this report indicate that uranium deposits formed in ancient stream channel, and the condition of climate was wet-hot situation. Uranium mineralizayion can divided into two type, one is basement mineralized type and the orther is stratabound type of sedimentary cover, especially basement-ancinet stream channel is the best background for uranium mineralization. Furthermore, this report point out that the genesis of uranium deposit can divided into many stage, and summarize corresponding mineralization pattern. And also forecast mineralized prospect in these three basin and find three favorable prospecting area in Longchuanjiang basin.