Characteristics And Metallogenic Significance Of Wall Rock Alteration In Zoujiashan Uranium Deposit,Xiangshan

The wall rock alteration of the Zoujiashan deposit in Xiangshan uranium ore-field develop widely.Systematic study of the wall rock alteration is advantageous to prospect uranium ores,to know the nature of uranium-bearing hydrothermal solution and the forms of transportation and precipitation mechanisms of uranium. Carrying on further investigation on it, we can have realistic theory meaning and practice meaning.Based on the comprehensive collecting,sorting and analyzing previous studies, combined with the field geological survey,selecting ore-bearing faults section from the surface to-250 m depth,sampled by the way of Penetrating the ore-body. And selected wall rocks and altered rocks of hydromicatization which have alternation intensity.The chemical composition analysis,EPMA,quantitative analysis of clay minerals were used to figure out the geological and geochemical characteristics of wall rock alteration from petrographic and geochemical perspective,and the relationship of hydromicatization and uranium mineralization.Then,understanding the evolution of wall rock alteration in time and space,speculating material composition and physicochemical conditions of U-bearing hydrothermal solution,and transportation and precipitation mechanisms of uranium, which are conducive to prospect the uranium metallogenic regularities, to enhance prospecting efficiency.Based on the above research,the following achievements have been obtained:(1) Revealed spatial distributed characteristics of near-ore wall rock alteration and main mineral association of ores and the altered rocks in Zoujiashan deposit.(2) Form wall rocks,near-ore altered rocks to mineralization center, the content of U,P2O5,Al2O3,Ti O2,Fe2O3,Mg O and LOI have significantly increased, Si O2 has obviously decreased.U is proportion to P2O5 and Ti O2. K2 O increased firstly and then decreased,Na2 O decreased, K2 O and Na2 O show an inverse correlation.Speculating that the late stage of U-bearing hydrothermal solution contained K,P,Al,Mg,Fe and less Na.The early stage of hydrothermal solution was alkaline and contained a certain amount of Na+.(3) With the increase of depth, Fe2O3 content decreased and Mg O increased. Contrary to surface rocks, K2 O content of deeper rocks are always higher than Na2 O.Such phenomenon show that,in the deep,the sodic metasomatism accounts for only a secondary position, k-metasomatism is dominant.(4) Form near-ore altered rocks to mineralization center,LREE and HREE both increased,but in the mineralization center,HREE is more rich.With the increase of depth,the HREE is more rich.(5) Analyzed the impacts of hydromicatization on composition of rocks,and the relationship of hydromicatization and uranium mineralization.