The discovery and geological significance of the volcanic-hosted beryllium occurrences at Mikengshan district,Jiangxi Province,South China
Volcanic-hosted beryllium deposit is an important type of beryllium resource,it provides over 80％of global beryllium resources annually.Therefore,the exploration and discovery of this type is crucial to improve the safe supply capacity of beryllium resources in China.On the basis of preliminary field geological investigation,analysis and testing,and geological profile measurement,three volcanic-hosted beryllium occurrences,such as Shangwan,Songdong and Rongjingba,were discovered in the terrestrial volcanic rock area of Mikengshan,Jiangxi Province,South China.According to the host rock,it can be divided into two types of mineralization:(1)topaz-bearing sulfide quartz vein in pyroclastic lava,and(2)altered rock type in the fractured zone in the tuff.Topaz-bearing sulfide quartz vein occur as large veins,veinlets,stockwork,and/or massive.It is mainly composed of topaz,quartz,muscovite,biotite,sphalerite,galena,cassiterite,wolframite,molybdenite,phenakite and bertrandite.At present,more than 20 topaz-bearing sulfide quartz vein have been discovered,with Be content range from 106 × 10-6 to 850 × 10-6.The altered rock type is mainly distributed along the fracture zone in the tuff,and the ore is mainly composed of quartz,fluorite,chlorite,sphalerite,galena,cassiterite,beryl,phenakite and bertrandite.Four altered fracture zones have been found in the tuff,which with Be content range from 40 × 10-6 to 2790 × 10-6.The Be concentration in altered fracture zone increased with the degree of chloritization alteration.The hydrothermal alterations related to beryllium mineralization are mainly composed of topazization,muscovitization,fluoritization,chloritization,and carbonatization.This paper obtains a zircon SHRIMP U-Pb age of 136.4±1.8Ma for porphyroclastic lava,two cassiterite U-Pb ages of 137.4±1.9Ma from topaz-bearing sulfide quartz vein in porphyroclastic lava and 134.7±4.8Ma from altered rock in the fractured zone in the tuff type,respectively.These two events formed almost simultaneously within the error range,which suggests the beryllium mineralization is close to or slightly later than the crystalline tuff deposition and porphyroclastic lava erupted in the region,and is related to volcanic magmatic activity.The discovery of volcanic-hosted beryllium occurrences not only provides a clue to search for this type of deposit in volcanic-sedimentary basins in the region,but also provides reference for the exploration for volcanic-hosted beryllium deposits in areas where porphyry and sub-volcanic tin deposits are developed.
Volcanic-hosted beryllium depositMetallogenic typeOre-forming ageMikengshanSouth China
万方数据
维普
