Characteristics Of The Alteration Rocks In Shuluqiu Uranium Deposit, Northern Guangdong

The hosted rock of the Shuluqiu uranium deposit is shallow red medium-c oarse porphyritic biotite K-feldspar granite,which is characterized by high SiO₂?Al₂O₃?Calc-alkaline continental and low CaO?P₂O₅?MgO?TiO₂ content,w hich is Peraluminous calc-alkaline crust-modified post-orogenic granite?S-type?.Average value of uranium content is 18.0×10^-6,which provides a partial uraniu m source for mineralization.According to the relationship between alteration and mineralization,the alt eration of Shulou-Qiu uranium deposit is divided into four stages,namely,auto metasomatism?muscovitization?alkali metasomatism?,pre-ore alteration?chloriti zation?hydromicazation?silicification?sericitization?epidotization?,metallogenet ic alteration?hematitization?pyritization?fluorization?carbonation?silicification?and post-ore alteration?silicification?carbonation?fluorization?.Among them,The alteration combination of pyritization,hematitization,fluorization,silicificati on can be used as prospecting landmark alteration.The horizontal alteration zone of Shuluqiu uranium deposit is divided into mineralization center zone,strong alteration side zone,weak alteration zone an d fresh granite zone according to the type,development degree,horizontal vari ation rule and relation with uranium deposit.The characteristic alteration assem blage changes are as follows:strong silicification+strong hematitization+pyritizat ion+fluorite+carbonate?strong hydromicazation+strong carbonation+strong chlorit ization+hydromicazation?weak hydromicazation+chloritization+sericitization+carb onation+epidotization?muscovitization+alkali metasomatism.The geochemical characteristics of main elements,trace elements and rare earth elements in each alteration zone are discussed by means of chemical tota l analysis.From the data of alteration mineral assemblage and chemical total a nalysis,the hydrothermal solution during mineralization period is enriched with Si?F?S?Fe?Ca?CO₃^-2.By means of cluster analysis with SPSS software,it is found that the element assemblages with high correlation between the min eralization center zone and U is Sr?Sc?W?Be;strong alteration zone is W?Sb?Cd;the weak alteration zone is Mo?Sb,can be used as a geochemical i ndicator for ore prospecting.According to the quantitative calculation,the geochemical background of fr esh rock of Shuluqiu deposit is that SiO₂?MgO?CaO?K₂O?Fe₂O₃?S?Li?Rb?Pb?Mo?W?Bi?Cd is the element which is finally brought into enrich ment with the fluid.The elements that eventually lead to loss with the fluid ar e Na₂O?Sr?Sc?Ga.It is calculated by electron probe that the pre-ore altered chlorite is mainl y prochlorite,a small amount of which is brunsvigite and chamoisite,and the formation temperature is about 220²70?.