Mineralization Types And Elemental Composition Characteristics Of The Rare Metal Field In Western Sichuan Jiajika

The rare metal ore field at the junction of the three counties of Kangding,Daofu and Yajiang in the Ganzi Prefecture of western Sichuan is one of the world’s largest hard rock type(granite pegmatite and fine-grained)rare metal deposits.The ore field has the characteristics of large scale,multiple minerals,and strong representative geological characteristics.It is an ideal target for the study of hard rock type rare metal deposits.In this paper,following the special project team,carried out two field geological surveys and outcrop sampling observations of the rock orebody in the Micaka field in 2016 and 2017 respectively.Based on previous research results and research data,this paper has observed,described and analyzed the geological characteristics of the Mikaka ore field,dyke,and orebody,and selected the veins X03 and No.134 as the vein representative.Detailed investigation.According to the research results of field geological features,indoor researches such as thin section identification and elemental geochemical analysis were conducted.Finally,the mineralization types and elemental combination characteristics of the ore fields were analyzed.The completion of the paper will provide a theoretical basis for future research and prospecting of ore fields.Mainly achieved the following new understanding:1.The "granite pegmatite veins" in the Jiajika orefield generally consist of(mineralized)fine-grained muscovite granite,coarse-grained granite,micrograined granite mass or lens body,quartz briquettes or quartz veins.Overlaid or interposed in space,it forms a complex rock mass.It cannot be referred to as the pegmatite vein.2.Li is enriched in spodumene,Rb is predominantly in microcline and muscovite,Nb,Ta are present in the group of middlings and muscovite,Be is enriched in beryl,and Sn is mainly Enriched in cassiterite,it is a common mineralization feature in the Jiajika field.According to the enrichment characteristics of mineralization elements,the types of mineralization in the methylka ore field can be divided into:Li mineralization type;Rb mineralization type;Nb-Ta mineralization type;Be mineralization type;Based on the correlation and cluster analysis,the element combinations were divided into three categories:Li;Rb;Nb-Ta-Be-Sn.3.Mica rock body has higher K2O,P2O5,TiO2,CaO and MgO content than dyke.Rb mineralized granites have high total alkali content,high aluminum,high potassium,and high sodium characteristics;Nb-Ta-Be-(Sn)mineralized granites belong to the calc-alkaline series with low potassium and high sodium characteristics;Li Mineralized granites are characterized by silicon-rich,low-sodium,and low-potassium.4.The contents of Ba,Sr,P,Zr,Ti and Y in the rock mass are higher than those in the dykes.Mineralized muscovite granitoids in Rb:K is enriched in lanthanum mineralized granite;it has obvious Nb negative anomaly and is different from Nb-Ta mineralized rock types.Nb-Ta mineralized or Be mineralized granitoids:U anomalies are more pronounced than in the rock mass;compared to Rb mineralized granitoids,K is a negative anomaly and relatively depleted.Li mineralized granitoids:There is a great degree of similarity with Nb-Ta mineralized or Be mineralized granitoids;the biggest difference between lanthanum mineralized muscovite granitoids and Majenzi granitoids is the relative loss of K.5.The total rare earth content of the rock mass is significantly higher than that of the dykes.Relative to the rock mass,the content of rare earth elements in Rb-mineralized granites is significantly lower,and the negative Eu anomaly is not obvious.Compared with other rocks,the curve of the distribution curve is the smallest and the fractionation degree is the lowest.The difference between the Nb-Ta-Be mineralized granite and the Li mineralized granite is that the total amount of rare earths in the lithium-mineralized granites is higher than that in the Nb-Ta-Be mineralized granitoids,compared to the rock masses and the Rb-mineralized granites.Both of them have relatively low HREE content and obvious negative Eu anomalies.