Geological Characteristics And Prospecting Prediction Of Rongxuka Rare Metal Deposit In Daofu County,Sichuan Province

The geotectonic location of the study area in the Rongxuka area is in the Songpan-Ganzi orogenic belt.This orogenic belt is one of the important rare metal metallogenic regions in China.The detailed data collection,geological survey,rock and mineral identification,and Geochemical data processing work of the study area were conducted in this paper.,combined with relevant research on geological characteristics,metallogenic conditions,and geochemical anomalies in the study area,this paper has achieved the following results:(1)In the Rongxuka study area,192 outcrop pegmatite veins have been discovered.The overall is the echelon distribution.There are three larger dikes including the northeast,northwest,and near north-south directions.The distribution is characterized by multiple controls such as structure,stratum,and magma.(2)The type of ore body is mainly composed of typical granitic pegmatite veins and a small amount of the composite rock body which mixed intermediate-fine grained granite and pegmatite microcline.The overall rock geochemistry of the ore veins is characterized by alkali-rich and peraluminous.The distribution pattern of rare earth elements is the right-dipping light rare-earth enrichment type and strong negative Eu anomaly characteristics.Veins and trace elements show enrichment of Rb,Ta,P,Hf,and depletion of Ba,Th,Sr,Zr,and Ti.(3)The overall mineralization elements in the study area are Li,Be,Nb,Ta,and Rb mineralization.It is a typical rare metal deposit,in which Li element is the main metallogenic element,and other elements are associated with mineralization or independent small-scale mineralization;The types of ore-bearing minerals in the area are relatively simple.The Li-containing minerals are mainly spodumene.The spodumene is generally in the form of coarse-grained,ranging in size from 5-10 cm,with a length of 10-20cm,and a few can reach 1cm.The direction of the long axis is often verticle;Be minerals are beryl,mostly acicular and fibrous,1-2cm in size,mostly clustered distribution;Nb and Ta are mainly concentrated in columbite;rich Rb minerals are microclase and muscovite,micro Plagioclase is generally in the form of a pegmatite column,about 10-20cm long,about 5-10cm wide,and it has a smooth surface and developed cleavages.(4)According to analysis results of soil element sample data and correlation analysis of data processing in the study area,the correlations of Li,Be,Nb,Ta,Sn,and Cs elements in the area are relatively good,and the background value of each element is much higher than that of the whole country.This area has a good prospect of metallogenesis;obvious concentration centers and clear anomalous ring structures can be seen in the integrated anomaly map of Li,Be,Nb,Ta,Sn,and Cs elements;Abnormal concentration centers are often concentrated near the outcrop of the pegmatite vein;this paper has divided six comprehensive anomaly zones,and appropriate projects have been arranged in the anomaly zone to expose the concealed ore body,which has a good mineralization response;this indicates that the method of soil geochemical anomalies in the study area is effective for finding sites of concentrated mineralization.(5)Based on the actual geological surveys,project construction,sample analysis results,and comprehensive geological anomaly verification,compared with the typical rare metal deposits in the region,it is considered that the study area has a large potential for prospecting rare metals,and the corresponding Six metallogenic target areas were identified in the study area,in which Li element has a good mineralization performance in each target area;Be element mineralization is better in the veins No.134 and No.120 and Panlonggou area,and in other areas some of the samples have reached the boundary grade;Rb elements showed the best mineralization in the area around the No.134 vein,and there was also a higher grade reaction in the No.6 vein in the No.1 target area.There was no obvious mineralization information in other areas;The Nb and Ta had the best mineralization reaction in No.134,followed by Panlonggou and No.120 veins;in this study,the Sn element has not reached the boundary grade in each target area,and the ore-forming prospect was weak.(6)The metallogenicity of rare metals in the study area is relatively complex.From the scale of the ore body and the analysis of sample data,the main metallogenic elements in the area are mostly Li or Be elements,but there are certain independent mineralization trends between Li and Be elements,for example,the No.4 vein is a typical Be vein,while Li does not reach the boundary grade;and the trial trench sample data show that the same element within the pegmatite vein has a large change in grade,reflecting the extremely uneven mineralization of the pegmatite vein.The mineralization sites of Nb,Ta,and Rb are mostly concentrated in the granitic complex massif,and the mineralization effect is poor in the typical granite pegmatite orebod.The ore-prospecting signs mainly include geomorphic signs,wall rock alteration signs,and quartz vein markers;among them,geomorphological signs are more effective for finding surface orebodies.Wall rock alterations and quartz vein markers are mainly used to find hidden pegmatites.Due to its high temperature and high pressure and rich in volatile components,Cordierite hornfels and tourmaline hornfels are widely developed in the area of contact zones,combined with previous achievements and the field observations,it was found that the size of the altered zone and the development of altered minerals are strictly controlled by the size of the intrusion body.Therefore,it is an effective and feasible method to find large-scale hidden pegmatite veins according to the change trend of the alteration zone.