层间氧化带砂岩型铀成矿过程中铁的地球化学行为——以新疆吐哈盆地十红滩铀矿床为例

Study on Iron Geochemical Behavior in the Interlayer Oxidation Zone Sandstone-type Uranium Metallogenetic Process: A case from Shihongtan uranium deposit in the Turpan-Hami Basin of Xinjiang

十红滩铀矿床形成于新疆吐哈盆地西南缘艾丁湖斜坡带的中侏罗统西山窑组河流相砂岩中,属典型的层间氧化带砂岩型铀矿床。物相分析表明,容矿层中铁的存在形式分别为FeCO3、Fe2O3、硅酸盐铁和FeS2,其含量在各地球化学亚带间发生有规律的变化。黄铁矿是容矿层二价铁的主要形式,具有两期成因特点,属硫酸盐微生物还原作用的产物。分析了铁的地球化学行为在铀成矿过程中的作用,认为在氧化带铁的氧化作用催化了铀的氧化、溶解以及迁移,为铀成矿提供了重要的铀源条件。矿石带中黄铁矿在铀成矿过程中发挥着吸附剂的作用,其与沥青铀矿等具有同成因特点。

As the typical interlayer oxidation zone sandstone type uranium deposit, Shihongtan uranium deposit occurs in the fluvial facies sandstone of the Xishanyao Formation of the middle Jurassic at the Aiding Lake slope in the south- west margin of Turpan-Hami basin. According to the results of ferrum phases analysis, the formations of iron element in the ore hosting belts include FeCO3 , Fe2 03 , silicate-facies iron and FeS2 whose contents take regular changes in different geochemical subzone. Pyrite, the main form of ferrous iron in the ore hosting belts, has the two-period cau- ses, belongs to the sulphate and microbe reducing product. The author analyzed the function of iron geochemical be- havior in uranium mineralization process, thought that in the oxidized zone, the iron catalyzed uranium oxidation, dis- solution and move, which provided the important source for uranium mineralization. The pyrite of ore belt played the sorption in uranium mineralization process, indicating the similar cause with the bitumionous uranium.