松辽盆地北部龙虎泡地区含铀岩系铀矿物赋存特征  

Characteristics of the occurrence of uranium minerals in U-bearing rocks of the Longhupao region in the northern Songliao Basin

作　　者：魏佳林 汤超 徐增连 陈路路 郭虎 苗培森[1] 谷社峰[3] 曾辉 WEI Jia-lin;TANG Chao;XU Zeng-lian;CHEN Lu-lu;GUO Hu;MIAO Pei-sen;GU She-feng;ZENG Hui(Tianjin Center,China Geological Survey,Tianjin 300170,China;Key Laboratory of Uranium Geology,China Geological Survey,Tianjin 300170,China;Exploration and Development Research Institute of Daqing Oilfield Co Ltd.,Daqing 163712,China)

机构地区：[1]中国地质调查局天津地质调查中心,天津300170 [2]中国地质调查局铀矿地质重点实验室,天津300170 [3]大庆油田有限责任公司勘探开发研究院,黑龙江大庆163712

出　　处：《矿物学报》2019年第6期709-725,共17页Acta Mineralogica Sinica

基　　金：国家重点基础研究计划(编号：2015CB453006);国家重点研发计划(编号：2018YFC0604206);中国地质调查局地质调查项目(编号：DD20190121)

摘　　要：近年来,砂岩型铀矿勘查工作在松辽盆地北部大庆长垣及周边地区取得重要找矿突破,并在龙虎泡地区深部层位发现了重要找矿线索。本文在钻孔岩芯编录、系统采样等野外工作基础上,利用偏光显微镜、电子探针以及铀价态分析等手段,对龙虎泡地区含铀岩系中铀矿物赋存特征进行了研究。研究表明,龙虎泡地区含铀岩系主要为四方台组底部曲流河相浅灰色砂岩,黄铁矿化与铀矿化关系密切。铀矿物类型主要为铀石,其次为富铀-铁钛氧化物,两者均与胶状黄铁矿紧密共生,另外还有少量含铀矿物碎屑石英,铀矿物成分分析显示,铀石普遍含有较高的P、Y,而这2种元素在富铀-铁钛氧化物中含量极少。能谱元素面扫描分析指示出,富铀-铁钛氧化物很可能为碎屑钛铁矿经后期含铀流体蚀变形成。含矿砂岩U4+/U6+比值分析和黄铁矿-钛铁矿矿物组合关系表明,龙虎泡地区含铀岩系的形成环境还原性较强。铀矿物赋存特征指示了龙虎泡含矿砂岩中的铀矿物具有多期次形成特点,在其形成过程中伴随有成矿环境的变化,从早期富铀铁钛氧化物到后期大量富磷-钇铀石的形成,成矿流体U、Si、P、Y等元素成分升高同时还原性减弱,流体耦合由早期以富H2S还原性流体为主趋于向后期以含铀含氧流体为主变化。Recently,an important breakthrough has been achieved on the exploration of sandstone-type uranium resource in the Changyuan of Daqing and adjacent areas in the northern Songliao basin.In addition,a significant clue for further uranium exploration has been found in the deep stratum in the Longhupao region.On the basis of field works including the geological logging of cores and systematic sampling,techniques including polarizing microscope,EMPA,and the analysis of uranium valence state were adopted to study the occurrence of uranium minerals in the uraniferous rocks in the Longhupao region in this paper.The study shows that these uraniferous rocks in the Longhupao region are mainly the light grey sandstones,in which pyritization is closely related to uranium mineralization,of the Quliuhe member at the bottom of the Sifangtai Formation.The main uranium-bearing minerals in this area include coffinite,U-rich Fe-Ti oxides,and clastic quartz containing uranium minerals.All of these coffinites and U-rich Fe-Ti oxides are genetically related to colloidal pyrites.The EPMA analytical results of uranium-bearing minerals show that the coffinite is generally rich in P and Y which are extremely poor in the U-rich Fe-Ti oxides.The EDS element mapping of the U-rich Fe-Ti oxides indicates that they could be produced from the altered detrital ilmenite by the late stage U-rich hydrothermal fluid.Moreover,the distribution characteristics of U4+/U6+ratios and the paragenetic association of pyrite-ilmenite of the U-rich sandstones indicate that the formation environment of these uraniferous rocks in the Longhupao area is a relatively strong reduced one.Characteristics of the uranium mineral occurrence indicate that the uranium minerals of the U-rich sandstone in the Longhupao area are characterized with the formation of multi-periods with the environmental variation in the uranium mineralization process.From the formation of early stage U-rich Fe-Ti oxides to the formation of late stage P-Y-rich coffinite,the U,Si,P and Y contents of

关 键 词：铀石 铁钛氧化物 四方台组 龙虎泡 松辽盆地北部 

分 类 号：P57[天文地球—矿物学] P611[天文地球—地质学]