| 准噶尔盆地西北缘西山窑组烃类流体作用特征及其铀成矿意义 |
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| 引用本文： | 黄少华,秦明宽,许强,何中波,郭强.准噶尔盆地西北缘西山窑组烃类流体作用特征及其铀成矿意义[J].地球科学,2019,44(9):3060-3073. |
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| 作者姓名： | 黄少华 秦明宽 许强 何中波 郭强 |
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| 作者单位： | 核工业北京地质研究院, 北京 100029 |
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| 基金项目： | 国防预研项目3210402中国核工业地质局项目地D1804国防科工局核能开发项目地H1142 |
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| 摘 要： | 目前对准噶尔盆地西北缘西山窑组烃类流体的性质、类型、作用特征及机理还未开展过系统研究，从而导致砂岩绿色化成因及其与铀矿化的关系仍不是十分清楚.对西山窑组原生灰色砂岩和绿色蚀变砂岩进行了野外岩心观察、光薄片镜下鉴定、X射线衍射、扫描电镜、化学全分析、流体包裹体以及C、O稳定同位素分析测试.结果表明:绿色蚀变砂岩普遍发育较强的粘土化（主要为蒙脱石化和绿泥石化）、黄铁矿化和碳酸盐化；其高岭石相对含量明显减少，还原容量增高；碳酸盐胶结物δ13CV-PDB明显偏负，为-12.8‰~-8.6‰，δ18OV-PDB为-11.7‰~-7.7‰；流体包裹体气体成分以CH4为主，含少量CO2.绿色蚀变砂岩遭受了偏碱性还原态烃类流体改造，进而掩盖保护了早期形成的古氧化带及古铀矿体，增加了找矿难度；且与近现代含氧含铀水相互作用形成了目前发现的铀矿体.
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| 关 键 词： | 中侏罗统西山窑组 绿色蚀变砂岩 烃类流体 铀矿体 准噶尔盆地 地球化学 |
| 收稿时间： | 2018-03-13 |
Hydrocarbon Fluid Geological Characteristics of the Xishanyao Formation and Its Uranium Metallogenic Significance,Northwest Junggar Basin |
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| Abstract: | The nature,type,function and mechanism of hydrocarbon fluids in Xishanyao Formation in Northwest Junggar Basin have not been systematically studied,and the genesis of the greenish alteration sandstone and its correlation with the sandstone-hosted uranium mineralization is still not clear. Through a series of measurements (e. g. rock-mineral identification,whole-rock geochemical test,fluid inclusion and C-O isotopic analysis),the mineralogical,geochemical,and isotopic characteristics have been researched for the primary gray sandstones and the greenish alteration sandstones,respectively. Petrographic observations indicate that the greenish alteration sandstones widespread a strong clay alteration (mainly montmorillonitization and chloritization),pyritization and carbonatization,and has less kaolinite content and high reduction capacity compared with the gray sandstones. The carbonate cements occurred in the greenish alteration sandstones have a light C-O isotope signature characterized by negative δ13CV-PDB values ranging from -12.8‰ to -8.6‰,and δ18OV-PDB values changing from -11.7‰ to -7.7‰. Furthermore,a large amount of methane and a little carbon dioxide have been identified within fluid inclusions. Therefore,the greenish alteration sandstones mostly experienced a reworking event by the deeply alkaline reductive hydrocarbon fluid,resulting in the concealment and protection of the paleo-oxidization sandstone belt and the early-formed uranium ore bodies,thus increasing the difficulty for prospecting. Besides,it produces the current discovered uranium ore bodies due to the interaction between the greenish sandstone and the modern uranium-bearing and oxygenated underground water. |
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