鄂尔多斯盆地南部双龙地区铀成矿特征分析
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摘要
利用新的勘查成果以及收集该地区的煤田勘查资料和前人的研究成果,详细分析鄂尔多斯盆地南部黄陵双龙地区的铀成矿特征。该区主要赋矿层位为中侏罗统直罗组下段下亚段(J2z1-1),为一套辨状河沉积,泥-砂-泥岩性结构稳定,砂体厚度适中,显示出良好的层间氧化带砂岩型铀矿成矿条件;区内发育渗入氧化蚀变和渗出还原蚀变,其中绿色蚀变是油气渗出二次还原氧化砂体而形成,是古氧化带的标志;利用沥青铀矿物U-Pb同位素年龄测定方法,测得双龙地区铀成矿时代可分为两期:早白垩世沉积成岩期,成矿年龄为125.2~98 Ma和始新世主成矿期,成矿年龄为52.6±2.2 Ma~41.8±9.3 Ma,与店头矿床属同期成矿。铀矿化赋存于斜坡带上隆起与洼陷的过渡部位,主要发育在古层间氧化带前锋线附近。研究发现,双龙地区显示良好的古层间氧化带砂岩型铀矿成矿潜力,具有广阔的勘查前景。
By means of collecting local coal exploration data and previous research results, uranium metallogenic characteristics of shuanglong area was analysed in detail based on new exploration results in Huangling of southern Ordos basin. The main ore hosting is the lower submember of low member of Middle Jurassic Zhiluo Formation(J2 z1-1)which is a set of braided river deposits, with stable rock combination of mudstone-sandstone-mudstone and the sand body is moderate of thickness, indicating good metallogenic conditions of interlayer oxidation zone sandstone type uranium deposits. Infiltrated oxy-alteration and exudate reduction alteration were well developed and the green alteration was believed to be the products of secondary reduction oxidized sand of oil and gas exudation, which was sign of paleo oxidation zone. Two uranium mineralization epochs were dated by the pitchblende U-Pb isotopic dating method. One is aged 125.2 ~98 Ma which responded to the period of sediment diagenesis in early Cretaceous, and another is aged 52.6 ±2.2 Ma ~41.8 ±9.3 Ma which was the metallogelic period in Eocene, the same age to Diantou uranium deposit. Uranium mineralization occurs intransition area between uplift and depression of slope zone, located in interlayer oxidation fronts. The research find that Shuanglong area shows good uranium mineralization potential of paleo-interlayer oxidation zone sandstone type which has a broad prospect of exploration and development.
By means of collecting local coal exploration data and previous research results, uranium metallogenic characteristics of shuanglong area was analysed in detail based on new exploration results in Huangling of southern Ordos basin. The main ore hosting is the lower submember of low member of Middle Jurassic Zhiluo Formation(J2 z1-1)which is a set of braided river deposits, with stable rock combination of mudstone-sandstone-mudstone and the sand body is moderate of thickness, indicating good metallogenic conditions of interlayer oxidation zone sandstone type uranium deposits. Infiltrated oxy-alteration and exudate reduction alteration were well developed and the green alteration was believed to be the products of secondary reduction oxidized sand of oil and gas exudation, which was sign of paleo oxidation zone. Two uranium mineralization epochs were dated by the pitchblende U-Pb isotopic dating method. One is aged 125.2 ~98 Ma which responded to the period of sediment diagenesis in early Cretaceous, and another is aged 52.6 ±2.2 Ma ~41.8 ±9.3 Ma which was the metallogelic period in Eocene, the same age to Diantou uranium deposit. Uranium mineralization occurs intransition area between uplift and depression of slope zone, located in interlayer oxidation fronts. The research find that Shuanglong area shows good uranium mineralization potential of paleo-interlayer oxidation zone sandstone type which has a broad prospect of exploration and development.
引文
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[2]张金带.我国铀资源潜力概略分析与铀矿地质勘查战略[J].铀矿地质,2004,20(5):260-265.
[3]毛明陆.渭北隆起北部构造分析与油气成藏预测[D].西安:西北大学,1997.
[4]陈宏斌,徐高中,王金平,等.鄂尔多斯盆地南缘店头铀矿床矿化特征及其与东胜铀矿床对比[J].地质学报,2006,80(5):724-732.
[5]邢秀娟,柳益群,樊爱平.鄂尔多斯盆地店头地区砂岩型铀矿成因初步探讨[J].中国地质,2006,33(3):591-597.
[6]李晓翠,刘武生,贾立城,等.鄂尔多斯盆地南部砂岩型铀矿成矿预测[J].铀矿地质,2014,30(6):321-327.
[7]陈瑞银,罗晓荣,陈占坤,等.鄂尔多斯盆地埋藏演化史恢复[J].石油学报,2006,27(2):43-47.
[8]赵孟为.鄂尔多斯盆地油气形成与运移时间和运移方向的确定与勘探方向[J].石油实验地质,1996,18(4):341-347.