The Tectonic Ore-Controlling Regularity And Metallogenic Prediction Of Uranium Deposits In Nanjia District Of Guizhou Province

As a new energy materials,uranium assumes the important task of "emission reduction",which is the world's urgent-need energy resources and strategic resources.Granite-type uranium deposit is one of the most important uranium type in China,with the characteristics of high grade and large amount.From the view of the lithological occurrence of uranium deposits,granite is the most important lithology,which has a good prospect and important resource potential.This paper based on the project of "The uranium copper polymetallic integrated exploration strategic selection in Congjiang county of Guizhou province",through a comprehensive analysis of the previous geological data,starting from the basic geological and mineral investigation,based on the theory of structural ore controlling,and combined with regional metallogenic geological background.In this area,the strata,magmatic rocks,tectonics,radioactive gamma intensity,ore(mineralized)body characteristics,ore-controlling tectonic characteristics and the geological characteristics of the typical uranium deposits compared to adjacent areas are systematically studied in this research.Summarizing the causes of uranium deposits in the area,the ore-controlling regularities,the ore-controlling modes,and carry out the research on the tectonic ore-controlling and metallogenic prediction of uranium deposits,it provides a reliable geological basis for the next uranium exploration work as well.Nanjia district is located in the joint of the south China plate and the Yangtze plate,the plate tectonic units belong to the southwest end of Jiangnan uplift belt,it's southwest adjacent to Youjiang orogene,and northwest side is the Yangtze massif,the uranium mineralization unit belongs to the Yangtze landmass uranium metallogenic province Xuefeng mountain-southwest Mo Tianlin uranium metallogenic belt.The area has experienced the multi-period tectonic movement and magmatic activities of the Four Fort,Xuefeng,Caledonian-Hercynian,Yanshan-Himalayan periods.The Jiyang rock mass in the Nanjia district is formed at the Xuefeng period,it is famous for its oldest uranium granite,which is a very important uranium granite body in northern Guangxi and southeastern Guizhou,even south China.Research shows that: 1)There are two large uranium mineralization in the area,which occurred at the Caledonian-Hercynian and Yanshan-Himalayan periods,both of which are related to the fault structure.2)The granite of the Nanjia district has similar characteristics with the uranium granite in South China.It has characteristics of rich silicon,rich alkali,aluminum supersaturation and super acidity.The uranium content is high in the rock mass,the background value is as high as 43×10-6 and the uranium leaching rate is higher.3)The ore-forming type is mainly composed of pitchblende and siliceous vein type,and the fault structure obviously control the ore,which is mainly produced in the NW-direction and NE-direction fissured silicification belt,intersection,expansion and contraction,uranium-bearing minerals mainly focus on pitchblende,the surface mainly have uranphyllite,calcouranite and other oxidants.4)NW fracture to F1 is the guide for mining in the area and ore structure,NW to secondary fracture F2,F3,F4,F5 and NE to fracture F6,F7 are the ore structure,and ore-controlling structure has the characteristics of multi-stage activities.5)The radioactive gamma anomalies are mainly distributed in the NW and NE trending silicification fracture zones and it's influencing zones.The gamma anomalies are in good agreement with the geologic information,and the range of gamma anomalies is(58~8800)×10-6.6)The time difference of rock forming is large in Nanjia district,the rock forming time is about 800-830 Ma in the this area,and the mineralization age of the uranium deposit is 56 Ma,which belongs to the low temperature mineralization of early stage in Himalayan periods,and the ore-forming temperature is about 100?~200?.7)The ore-forming fluids in the Nanjia district are from the surface water.During the Yanshan-Himalayan period,the surface water is combined with CO2 and O2 as the ore-forming medium to leach the uranium elements in the granite debris and enter the rock mass through the fault structure and heat,reacting with the rock and repeatedly extracts uranium from the granite to form uranium-rich hydrothermal fluids,under the action of tectonism,it is migrated to the tectonic low pressure area to enrich the mineralization.According to the geological conditions of mineralization and the research achievements in this area,favorable area for mineralization was predicted,the target area is divided into two types,two in the ore prospecting target area and one in the secondary ore prospecting area.