Geological And Geochemical Characteristics Of K Deposit And Its Metallogenic Environment Implication, Wanshan, Guizhou Province

Wanshan is an important producting area of K deposit in Guizhou province. This paper not only has got a preliminary study on metallogenic environment and regularity, but also proposed metallogenetic model of K deposit in Wanshan by a comprehensive sorting out of the geological, petrological and geochemistry characteristics of K deposit in mining areas.Wanshan potassium mine is located in the transition part of Yangtze paraplatform and south China fold belt, between Tongren fault and Xiaxi anticline, and is divided into North West and South East two parts by Aozhai fault. The K deposit occur in the shale of second Member of Aoxi formation of the Middle Cambrian series. The K occurs in aluminosilicate by element state and the main mineral is illite. Ore texture mainly is ispelitic, silt bearing ispelitic texture, and the main structure includes micro stratified, foliation and directional structure. The color of ore can be divided into gray, gray-black and yellow-gray, yellow-green two types, with the law that the yellow-gray and yellow-green is on the top of the yellow-gray, yellow-green one.The major elements data of K deposit has the feature that the K2O content is between7.4～9.99, medium SiO2content and high K2O/Na2O ratio. We can draw a conclusion that the terrigenous K deposit of the study area are deposited on weak oxidation to weak reduction passive continental margin, belong to normal marine environment by analyzing the major and trace elements datas’ SiO2/Al2O3ratio, Al/(Al+Fe+Mn) ratio, K2O/Na2O-SiO2and K2O/Na2O-SiO2/Al2O3graphic, U/Th ratio, δ U, V/Cr ratio and U-Th graphic.Rare earth elements data shows that light REE are enriched, Ce anomalies are weak and heavy REE are flat. The chondrite-normalized REE patterns and the North American shale normalized REE patterns are both right-incline, with the difference that the REE curve normalized by NASC is horizontal and the chondrite-normalized REE patterns have obvious negative Eu anomalies. The δEu、Ceanom、La/Yb-ΣREE and La/Yb-Ce/La graphic of rare earth elements datas confirm the thesis of sedimentary environment concluded by the major and trace elements parameters.