Metallogenic Condition And Prospecting Prognosis Of Ion Adsorption Rare Earth Deposits In Chongzuo Area,Guangxi Province

The research area is located in Qujiu-Pingxiang Friendship Pass-Shuikou area,Chongzuo City,southwestern Guangxi.It is situated in the complex part of Yangtze plate and Cathaysian landmass junction zone(Qin-Hang junction zone),and in the southwestern end of Xidaming uplift area of Youjiang fold system.The ion-adsorbed rare earth minerals in this area are located in the weathering crust of the early Triassic intermediate-acid volcanic rocks.At present,only the Liutang rare earth deposit being mined has reached the level of detailed investigation,while the other known Jiangzhou and Daqingshan deposits have only carried out census work.The metallogenic geological conditions of this area are superior,the prospecting criteria are obvious,and it has better prospecting potential.Starting from the analysis of regional geological background,this paper makes a thorough study of the geological characteristics of the mining area,the geological characteristics of the deposit,the regularity of mineralization enrichment and the distribution characteristics of rare earth elements.It also analyses the endogenous conditions such as tectonic conditions,the conditions of ore-forming parent rocks,and the effects of the physical and chemical conditions,climatic conditions and topographic and geomorphological conditions of the weathering crust medium on the mineralization,and draws the following conclusions.:1.The middle-acidic volcanic rocks rich in rare earth elements in the Early-Middle Triassic in Chongzuo area provide abundant material sources for mineralization.The subtropical monsoon climate conditions are conducive to the formation of weathering crusts with high chemical weathering degree,the activation and migration of rare earth elements and the enrichment of mineralization.The middle-low mountain-hilly landforms in this area are conducive to the development of weathering crusts and the preservation of ore bodies.2.The known REE deposits in this area are mainly distributed in the weathering crust of the early Triassic intermediate-acid volcanic rocks on the north side of the Pingxiang-Dongmen active fault zone.The distribution characteristics of the ore bodies are obviously controlled by volcanic rocks and geological structures.The irregular surface orebodies are the main ones,and the dip angle is similar to the geomorphic slope direction.3.The content of REE varies with the abundance of REE in the parent rocks,and is mainly concentrated vertically from the lower part of the whole weathering layer to the upper part of the semi-weathering layer.4.By summarizing the geological characteristics and genesis of known deposits and combining with regional geological and tectonic conditions,four grade I prospecting and prediction targets,three grade II prospecting and prediction targets and one grade III prospecting and prediction target were delineated in the weathering crust of intermediate-acid volcanic rocks of the Early-Middle Triassic.