622铀矿床近矿围岩蚀变地质地球化学特征

GEOLOGLCAL AND GEOCHEMIC AL FEATURES OF WALLROCK AL TERATION OF SURROUNDING ORE MINERALIZATION INURANIUM DEPOSIT 622

Based on the geological field and micrdscope observation of wallrock alteration of u- ranium deposit 622 and field and microscope geochemcal trace of major element and rare earth el-ement , two main periods of hydrothermal actions closely related to mineralization have been classi- fied here,The first is alkalic metasomatism and hematite type of uranium mineraliZation withmiddle enrichment of H R E E caused by alkalic hydrothermal action from the deeper magmatismand late mineralizatian. The second is acid hydrothermal action produced by near- surface circulat- ing underground water which was mainly from atmosphere. This process brought about furtherfractionation of LREE and HREE high HREE concentration , and superimposition of fluorite-damourite type of U ranium metallogenesis. It is suggested that hematitization , fluoritization anddamouritization phenomena which are widespread in the alterated metallogenic zone , the contentincrease of P_2O_5,MgO,TiO_2,CaO, REE and HREE,the decrease of SiO_2,Na_2Oand the ratio of LREE/HREE ,can be used as criteria for ore prospecting.