新疆哈密大南湖地区层间氧化带型铀成矿作用

矿化区位于新疆吐哈盆地东南缘的大南湖凹陷东部,铀矿化赋存层位为中侏罗统西山窑组上段和中段上部,上段主要为冲积扇和辫状河沉积；中段主要为曲流河和三角洲沉积.铀矿石的特征元素有机碳orgC、CO2、∑S的化学分析平均值分别为0.42％、4.19％、0.38％,明显高于大南湖地区相应岩石的平均值0.34％、0.40％、0.14％,反映U元素的富集明显与其相关.铀矿石所分析的7种微量元素,其平均值均大于大南湖地区砂岩相应元素的平均值,反映了层间氧化作用可能是微量元素迁移富集的机制之一.铀矿化厚度4.9m,品位为1.902×10-4,U含量为1.996 kg/m2.矿体形态为板状.含矿岩石主要为褐黄色、灰色中一粗粒长石岩屑砂岩、砂质砾岩、砾岩.大南湖地区含矿层位中侏罗统西山窑组岩石原生地球化学类型为黑色和灰色.铀的存在形式以吸附状态为主.区内的铀矿化类型属层间氧化带型.铀矿化形成于氧化-还原过渡带,与层间氧化带发育存在直接的成因关系.

Characteristics of Uranium Mineralization from Interlayer Oxidized Zone in Dananhu Area of Hami,Xinjiang

Mineralized area lies to the east of Dananhu depression in east-southern edge of Turpan-Hami Basin of Xinjiang.The horizon of uranium mineralization is formed mainly in the upper and middle-upper lithologic member of Xishanyao Formation of Meso-Jurassic series,the upper member is mainly alluvial fan and braided stream deposit,and the middle-upper member is mainly meandering stream and deltaic deposit.The mean values of chemical analysis of orgC,CO2,and ∑S are respectively 0.42%,4.19%,and 0.38% for diagnostic element of uranium ore,obviously higher than the mean values 0.34%,0.4%,and 0.14% of relevant rock in Danahu area,reflecting the uranium element enrichment is related to this.In uranium ore,the mean value of the 7 microelements analyzed are all higher than the relevant elements of Danahu area sandstone,indicating the interlayer oxidation maybe one of the reasons for microelement migration and enrichment.The thickness of uranium mineralization is 4.9 m,grade is 1.902×10-4,and uranium content is 1.996kg/m2.The shape of ore-body is platy.Pay rock are mainly brown-yellow and gray medium-coarse-grained feldspathic litharenite,sandy conglomerate,conglomerate.Rock primany geochemical type ore-bearing bed Meso Jurassic series Xishanyao Formation are black and grey in Danahu area.Uranium existent form is mainly adsorption shape.Uranium mineralization type is interlayer oxidied zone type.Uranium mineralization grew on reduction-oxidation intermediate zone,there was immediately genetic relationship between uranium mineralization and interlayer oxidied zone development.