| 巴音戈壁盆地塔木素铀矿床含矿砂岩成岩作用类型、演化序列及其对铀成矿的约束 |
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| 引用本文：张成勇,夏菲,严兆彬,邓薇,聂逢君,张鹏飞,文振宇,刘波,戴明建,封志兵.2021.巴音戈壁盆地塔木素铀矿床含矿砂岩成岩作用类型、演化序列及其对铀成矿的约束[J].地球学报,42(6):907-920. |
| DOI：10.3975/cagsb.2021.092702 |
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| 基金项目:国家自然科学基金项目(编号: 42062008; 41862010; 42072099; U2067202);国家重点研发计划项目(编号: 2015CB453002);江西省教育厅科学计划项目(编号: GJJ180363);东华理工大学放射性地质与勘探技术国防重点学科实验室开放基金项目(编号: RGET1612) |
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| 中文摘要:勘查和研究发现部分砂岩型铀矿床中不仅有表生氧化流体作用还存在深部流体的参与, 这类砂岩型铀矿床蚀变类型多样且成因复杂。塔木素砂岩型铀矿表生流体和深部流体活动都很明显, 砂岩普遍固结且后生蚀变类型独特, 因此, 恢复成岩成矿事件及其演化过程, 对揭示铀沉淀富集机理至关重要。本文通过镜下鉴定、电子探针、扫描电镜分析等, 系统研究了塔木素矿床含矿砂岩成岩作用特征与后生蚀变矿物生成序列, 重塑了成岩成矿事件的演化过程。研究结果显示, 塔木素矿床砂岩中压实作用较弱而胶结作用很强, 重结晶作用普遍, 是造成目的层致密的主要原因, 赤铁矿、褐铁矿化、碳酸盐化、石膏化是该地区主要的胶结类型。将该地区的成岩演化划分为沉积-早成岩阶段、早期氧化流体作用阶段、热流体改造阶段和晚期氧化流体弱改造阶段。成岩环境由弱碱性向酸性环境转变的过程中的氧化还原过渡部位是造成铀沉淀的关键, 大规模的氧化作用是矿床形成的基础, 后期热流体活动对早期形成的低品位铀矿石进行叠加改造, 是成矿的关键环节。 |
| 中文关键词:塔木素 砂岩型铀矿 成岩作用 热流体活动 成矿环境 |
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| Diagenesis Types and Evolution Sequence of Ore Bearing Sandstone and Their Constraints on Uranium Mineralization in Tamusu Uranium Deposit, Bayingobi Basin |
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| Abstract:Exploration and research show that some sandstone-type uranium deposits not only contain superoxide fluids, but also deep hydrothermal activity fluids. These sandstone-type uranium deposits have a wide variety of alteration types and a complex the genesis. In the Tamusu sandstone-type uranium deposit, the action of both supergene oxidation and deep hydrothermal activity fluids is obvious. The ore-bearing sandstone is generally consolidated due to hydrothermal transformation. Based on microscopic identification, Electron Probe Microanalysis,and Scanning Electron Microscope, this study systematically studied the diagenesis, characteristics of ore bearing sandstone, and the generation sequence of epigenetic altered minerals, in the Tamusu deposit, and assessed the evolution process of diagenetic and metallogenic events. The results suggest that the main reasons for the densification of the target layer are weak compaction, strong cementation, and widespread recrystallization. Hematite, limonitization, carbonation, and gypsum are the main cementation types in the area. The diagenetic evolution of the area can be divided into sedimentary early diagenetic, early oxidation fluid action, thermal fluid transformation, and late oxidation fluid weak transformation stages. Based on the study of the temporal and spatial variation of the metallogenic environment, it is believed that the key to uranium precipitation is the change in the redox transition site environment from a weak alkaline to an acidic environment during diagenesis. Large scale oxidation was the basis for the formation of the deposit, and the key to mineralization was the superimposition of the low-grade uranium ore formed in the early stage by the late thermal fluid activity. This study not only enriches the metallogenic theory of sandstone-type uranium deposits, but also guides the future exploration of this area. |
| keywords:Tamusu sandstone-type uranium deposit diagenesis hydrothermal fluids metallogenic environment |
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