| 鄂尔多斯盆地南缘双龙地区直罗组下段后生蚀变地球化学特征及其对铀成矿的制约 |
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| 引用本文： | 刘阳,王军礼,曹惠锋,计波.鄂尔多斯盆地南缘双龙地区直罗组下段后生蚀变地球化学特征及其对铀成矿的制约[J].地质科技通报,2021,40(6):77-87. |
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| 作者姓名： | 刘阳 王军礼 曹惠锋 计波 |
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| 基金项目： | 国家重点基础发展计划2015CB45300中国地质调查局项目"718工程"DD20170128中陕核工业集团公司科技攻关项目61180104 |
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| 摘 要： | 勘探实践发现，双龙地区砂岩型铀矿受绿色蚀变控制，与东胜地区相似。为明确区内层间氧化带的地球化学识别标志，通过对研究区直罗组下段砂岩后生蚀变的宏观表征观察和酸解烃、Th/U、Fe3+/Fe2+及有机碳等的地球化学研究，并与东胜铀矿床对比，探讨了双龙矿床绿色砂岩的成因，并讨论后生蚀变作用对铀成矿的影响机制。分析结果表明:原生灰色砂岩各类烃含量高于绿色蚀变砂岩和氧化蚀变砂岩，绿色蚀变砂岩介于两者之间；Th/U、Fe3+/Fe2+和有机碳质量分数分别在0.37~1.82，0.06~5.09，0.01%~1.24%之间，氧化蚀变砂岩与绿色蚀变砂岩皆具有高Th/U值、低有机碳的特征，而绿色蚀变砂岩的各地球化学指标介于氧化蚀变砂岩和原生灰色砂岩之间。总之，双龙地区直罗组下段的蚀变砂岩地球化学特征显示，绿色蚀变是砂岩处于一种相对较强的还原状态下形成的产物，即还原性流体的二次还原作用，早期的层间氧化作用为铀成矿提供了物质基础，后期的二次还原作用则保存了矿体的完整性。这一研究对该区层间氧化带的判别及划分具有重要的指示作用，并为砂岩型铀矿成矿规律的研究提供重要依据。
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| 关 键 词： | 双龙地区 直罗组 砂岩型铀矿 地球化学 |
| 收稿时间： | 2020-12-30 |
Geochemical characteristics of epigenetic alteration and its constraints on mineralization in lower segment of Zhiluo Formation,Shuanglong area,southern Ordos Basin |
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| Abstract: | Green-color sandstone illustrates close association to the deposition of sandstone-type uranium via field exploration, which is similar to the Dongsheng area. Geochemical research on acidolysis hydrocarbon, Th/U, Fe3+/Fe2+ and organic carbon content in Zhiluo Formation were conducted, aiming to decipher the uranium mineralization in the green color sandstone.The result shows that: (1) Primary gray sandstone hold the higher content of hydrocarbon than the green altered and oxidized ones, and then the green altered sandstone.(2)Both oxidized sandstone and green alteration sandstone were chartererised by high Th/U (0.37-1.82) and low organic content (0.01%-1.24%).Green alteration was probably triggered by intensive reduced material, that is, the secondary reduction of reducing fluid.The early interlayer oxidation provided the material basis for uranium mineralization, and the later secondary reduction preserved the integrity of the ore body.This study has an important indication for the discrimination and division of interlayer oxidation zone in this area, and provides an important basis for the study of metallogenic regularity of sandstone type uranium deposits. |
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