水岩体系Eh-pH法确定铀矿层间氧化带尖灭地段的研究

STUDY OF DETERMINING THE ANNIHILATING LOCATION OF INTERLAYER OXIDATION ZONE BY WATER-ROCK SYSTEM Eh-pH METHOD

砂岩型铀矿主要产在层间氧化带的尖灭地段 ,在地表无露头 ,因此有必要对层间氧化带尖灭地段的确定方法进行研究。为了能较为客观地反映铀矿的成矿环境 ,更准确地确定铀矿层间氧化带尖灭地段的位置 ,利用水岩体系Eh pH法在新疆伊犁 5 12砂岩型铀矿床中进行了研究。结果表明 ,Eh值在氧化带为高正值 ,在过渡带与还原带为低负值 ;pH值在氧化 还原过渡带接近中性 ;结合水 铀平衡区间图解 ,以水岩体系Eh值作为主要的分带指标 ,可以划分出层间氧化带的 4个分带的Eh值范围 ,从而可以精确地确定层间氧化带尖灭地段即铀矿石带的位置。该方法在国内砂岩型铀矿床中首次得到应用。

Sandstone type uranium ore bodies generally exist in the annihilating location of interlayer oxidation zone, and there is no outcrop on the surface. It's of necessity to study the methods of determining the interlayer oxidation zone's annihilating location. For the purp ose of more o bjectively reflecting the environment of uranium deposit formation and more accu rately determining the annihilating location of interlayer oxidation zone, this paper studies the water-rock system Eh-pH method applied to the Yili 512 s andstone type uranium deposit. The study shows that the value of Eh is high positive in the oxidation zone and is low negative in the transition zone and re duction zone. The results also show that pH is close to neutrality in the transi tion zone. Combined with the range of water-uranium equilibrium diagram, four Eh scopes of interlayer oxidation zone can be divided by the index Eh. T herefore water-rock system Eh-pH can be used to determine the annihilating location of interlayer oxidation zone accurately. This method is the first to b e applied to sandstone type uranium deposit in China.