Geological And Geochemical Characteristics And Genetic Analysis Of Bingcaogou Uranium-Phosphate Deposit In North Tianshan

Bingcaogou U-P deposit is controlled by the contact interface between the basaltic andesiteand sandstone in north Tianshan,andis a typical hydrothermal uranium-phosphorus deposit.this article,the typical section of across ore body is taken as the research object,research petrography,mineralography and section geochemistry of U-P ore and ore-hosting strata by means of microscope,XRF,ICP-MS,and discussed element migration law in metallogenic process.With the help of alpha tracks etching,microscope,SEM,EMPA,and XRD powder diffraction,this article analyzed Uranium Occurrences and the type of collophane in ore.This paper studied the U-Pb chronology of zircon in the ore by LA-ICP-MS,and preliminarily discussed the possible metallogenic age of this ore deposit.,This paper studied In-situ trace and Sr isotope of U-P ore and ore-hosting strata with the help of LA-ICP-MS.on the basis of above work,the integrating previous research results,this paper summarized the geological and geochemical characteristics of Bingcaogou U-P deposit,and also discussed the characteristics of the ore-forming fluids,the controlling factors of the ore body spatial orientation,the uranium-phosphorus sedimentation mechanism and the genesis of the U-P deposit.The research results and conclusions are as follows:?1?Mineralogical studies show that collophane,as an ore mineral,is mainly produced in agglomerate and colloidal form,partially in short columnar or acicular,metasomatic along the edge of gangue minerals such as ilmenite,zircon,barite and albite.The results of EMPA test showed that the UO₂ content of Collophane range from 0.33%to 0.59%,with the help of high fluorine and low chlorine content,the CaO/P₂O₅ of Collophane ratio,and,The XRD powder diffraction results,it show that the collophane is mainly fluoropatite.Experiments of ore track etching show that U is mainly distributed in fluoropatite.?2?Section geochemical results show that,Uranium and phosphorus were enriched simultaneously in the process of mineralization.In section,in addition to U and P,the ore is also highly enriched with Ca,Sr,Zr,Th,HREE and Y.Combined with electron probe and gelophosphorite LA-ICP-MS test results,it is believed that the mineralization fluid has strong oxidation,and,may be rich in Ca,P,U,Ba,Sr,Zr,HREE and Y,as well as a fluid rich in fluorine and low chlorine.?3?Fresh basaltic andesites have relatively high FeO content?4.74%?and low OX value?0.9?,indicating that fresh basaltic andesites show strong reduction capacity,which may provide reduction barriers for the spatial positioning of uranium ore bodies.Therefore,the redox interface is the main factor controlling the spatial orientation of the deposit.?4?The results of LA-ICP-MS test showed that the collophane showed the characteristics of heavy rare earth enrichment but light rare earth loss,and the trace elements and rare earth elements in the whole rock of ores were controlled by collophane,indicating the hydrothermal genesis.The I_Srr value of ore-forming fluid is between0.705975 and 0.70624,with an average value of 0.706037.It is believed that the ore-forming fluid may not be directly from the mantle;it is higher than the I_Srr value of the basaltic andesite(the average value of I_Srr is 0.703038),which may not be directly derived from the hydrothermal differentiation of magma crystallization.It is close to the new crust,indicating that the ore-forming fluid may be related to the crust.Combined with the Nb/Ta ratio and the high fluorine and low chlorine characteristics of the collophane,it is preliminarily believed that the ore-forming hydrothermal fluid may be related to the hydrothermal fluid in which the crustal part is melted and crystallized in the late stage.