| 柴北缘冷湖地区砂岩型铀矿床地质特征及成矿条件分析 |
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| 引用本文： | 黄广楠,黄广文,王伟超,陈正乐,严翔,俞礽安,张成勇.柴北缘冷湖地区砂岩型铀矿床地质特征及成矿条件分析[J].中国地质,2021,48(4):1200-1211. |
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| 作者姓名： | 黄广楠 黄广文 王伟超 陈正乐 严翔 俞礽安 张成勇 |
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| 作者单位： | 青海煤炭地质一○五勘探队, 青海 西宁 810007;青藏高原北部地质过程与矿产资源重点实验室, 青海 西宁 810012;青藏高原北部地质过程与矿产资源重点实验室, 青海 西宁 810012;东华理工大学核资源与环境国家重点实验室, 江西 南昌 330013;中国地质科学院地质力学研究所, 北京 100081;中国地质调查局天津地质调查中心, 天津 300170 |
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| 基金项目： | 青海省青藏高原北部地质过程与矿产资源重点实验室资助项目（2019-KY-04）、中国地质调查局地质调查项目（DD20160127）、青海省科技厅基础研究计划项目（2018-ZJ-779）及青藏高原二次科考项目（2019QZKK0702）联合资助。 |
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| 摘 要： | 冷湖地区砂岩型铀矿是近年柴北缘新发现的具有工业价值的铀矿床,为了进一步研究该地区砂岩型铀成矿岩石学及矿物学特征、铀成矿条件等问题,本文在野外地质调查的基础上,利用偏光显微镜结合电子探针分析手段,对该区内大煤沟组中含矿岩石进行了系统研究。结果表明:研究区中侏罗统大煤沟组含矿岩石类型主要为(粉)砂质泥岩、薄层煤及细粒石英杂砂岩,整体发育一系列后生蚀变。研究区北东侧安南坝山古元古界达肯达坂群及赛什腾山海西期花岗岩为区内砂岩型铀成矿提供了丰富的铀源。砂岩型铀矿中铀主要以独立铀矿物沥青铀矿的形式赋存,其次含有少量分散吸附态铀,沥青铀矿总体呈不规则粒状、星点状、"串珠状、线状"及粉末状赋存于黄铁矿边缘、裂隙部位或黄铁矿与方解石的接触部位,吸附态铀主要赋存于炭屑及煤线内;区内沥青铀矿为柴北缘地区首次揭露并发现的独立铀矿物,总体上填补了柴北缘地区无独立铀矿物出露的空白。铀成矿条件方面,含矿目的层中方解石的发育,显示了铀成矿流体富含CO_2、H_2O等挥发分和矿化剂,其次出露的众多还原性介质(油气、炭屑及黄铁矿等)为区内砂岩型铀成矿提供了氧化还原反应必需的还原剂,最终将U~(6+)还原成U~(4+)以沥青铀矿等形式沉淀成矿。
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| 关 键 词： | 砂岩型铀矿 沥青铀矿 电子探针 柴北缘 冷湖地区 地质调查工程 青海省 |
| 收稿时间： | 2020/6/5 0:00:00 |
| 修稿时间： | 2021/6/1 0:00:00 |
Geology and minerogenetic condition of the Lenghu sandstone-type uranium deposit in the northern margin of Qaidam Basin |
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| HUANG Guangnan,HUANG Guangwen,WANG Weichao,CHEN Zhengle,YAN Xiang,YU Reng''an,ZHANG Chengyong.Geology and minerogenetic condition of the Lenghu sandstone-type uranium deposit in the northern margin of Qaidam Basin[J].Chinese Geology,2021,48(4):1200-1211. |
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| Authors: | HUANG Guangnan HUANG Guangwen WANG Weichao CHEN Zhengle YAN Xiang YU Reng'an ZHANG Chengyong |
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| Institution: | No. 105 Exploration Team, Qinghai Bureau of Coal Geological Exploratio, Xining 810007, Qinghai, China;Key Laboratory of the Northern Qinghai-Tibet Plateau Geological Processes and Mineral Resources, Xining 810012, Qinghai, China;Key Laboratory of the Northern Qinghai-Tibet Plateau Geological Processes and Mineral Resources, Xining 810012, Qinghai, China;State Key Laboratory of Nuclear Resources and Environment, East China University of Technology, Nanchang 330013, Jiangxi, China;Institute of Geomechanics, Chinese Academy of Geological Sciences, Beijing 100081, China;Tianjin Geological Survey Center of China Geological Survey, Tianjin 300170, China |
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| Abstract: | The Lenghu sandstone-type uranium deposit is the newly discovered industrial deposit in the northern margin of Qaidam basin. Based on the field geological survey, the ore-bearing rocks in the Dameigou Formation in this area were studied by means of polarizing microscope and electron probe analysis to further clarify the characteristics of uranium source, petrology and mineralogy of Lenghu sandstone-hosted uranium deposit. Results show that the ore-bearing rocks in the Dameigou Formation are mainly (silty) sandy mudstone and thin layer coal and fine-grained quartz greywacke, accompanied with a series of epigenetic alteration phenomena. The Lower Proterozoic Dakendaban Group and Hercynian granite in the northeastern part of the study area provide abundant uranium sources for uranium mineralization. The uranium minerals in this deposit are mainly pitchblende and minor adsorption state of uranium. In general, the pitchblende occurs in irregular granular, stellate, "beadlike, linear" and powdery forms at the edge of pyrite, in the crack or on the contact between pyrite and calcite. The adsorbed uranium mainly occurs in the carbon chips and coal lines. The pitchblende deposit is the first exposed and discovered independent uranium mineral in the northern margin of Qaidam basin, which generally fills the blank of no independent uranium mineral exposed in this area. The presence of calcite in ore-bearing layer indicates that the uranium mineralization fluid is rich in CO2, H2O etc. volatile and mineralizer. In addition, many exposed reducing medium (oil and gas, carbon and pyrite, etc.) provides reductant required for REDOX reaction of this type of deposit, which eventually reduces U6+ to U4+ and results in precipitation of pitchblende. |
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| Keywords: | sandstone-type uranium deposit pitchblende electron probe northern margin of Qaidam basin Lenghu area geological survey Qinghai Province |
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