内蒙古开鲁盆地砂岩型铀矿热流体作用  

Hot fluid flows in the sandstone-type uranium deposit in the Kailu basin, Northeast China

作　　者：聂逢君[1] 严兆彬[1] 夏菲[1] 李满根[1] 卢亚运 蔡建芳[3] 郭福能 宁君[3] 

机构地区：[1]东华理工大学核资源与环境国家重点实验室培育基地,江西南昌330013 [2]核工业航测遥感中心,河北石家庄050002 [3]核工业二四三大队,内蒙古赤峰024000

出　　处：《地质通报》2017年第10期1850-1866,共17页Geological Bulletin of China

基　　金：国家重点基础研究发展规划973计划<中国北方砂岩型铀矿流体成矿过程研究>(编号:2015CB453002);国家自然科学基金项目<吐哈盆地南缘挤压背景下的层间-渗入铀成矿作用>(批准号:40972067);<二连盆地西缘隆起区卫境岩体抬升剥蚀与盆内铀成矿耦合机理研究>(批准号:41772068)

摘　　要：开鲁盆地钱家店-白兴吐矿床的发现为中国东部晚侏罗世以来伸展裂陷型盆地中寻找可地浸砂岩型铀矿提供了典范。研究发现,钱家店-白兴吐矿床及其周围断裂构造十分发育,尤其是著名的西拉木伦河断裂在矿床中直穿而过。勘查实践表明,70%~80%的钻孔中能见到辉绿岩,矿化体多呈囊状、透镜状,空间上矿化与辉绿岩有关。通过岩心观察、镜下薄片鉴定、电子探针分析、包裹体温度与盐度的测定,发现上白垩统姚家组含矿目的层砂岩中存在大量的热流体改造证据。辉绿岩侵入过程中热作用不仅使围岩出现烘烤变色、变硬,而且辉绿岩岩浆作用带来的热流体使砂岩、泥岩产生大量的新生胶结物。与辉绿岩相关的热流体作用使姚家组含矿目的层砂岩中的碎屑颗粒被溶解和交代,无论是宏观还是微观上,均可见到碳酸盐脉体,同时碳酸盐矿物蚀变交代石英、长石。进一步研究表明,碳酸盐胶结物可分出第一期方解石、第二期铁白云石和第三期高铁白云石。碳酸盐胶结物和石英次生加大边包裹体测温显示,钱家店-白兴吐砂岩型铀矿床热流体改造有3期热流体活动,对应的温度分别为80~90℃、110~120℃和140~150℃。测定冰点获得的包裹体盐度分布也有低盐度区、中盐度区、高盐度区3个区间,它们与3期不同温度的热流体活动相对应。The discovery of the Qianjiadian-Baixingtu uranium deposit(QBUD) in the Kailu basin extremely encourages explorers to look for in-situ leaching uranium deposits(ISLUD) in the post-Jurassic extensional basins in Northeast China. There is a well-developed faulted system in and near QBUD. The famous Xilamulun River fault passes through the deposit. Diabase related to regional faults is extensive throughout QBUD. It is estimated that 70%~80% of the exploration drilling holes meet the diabase beds. The cystic and lenticular orebodies in QBUD conflict with the interlayered oxidation genesis, which holds the generation of rollfront or tabular orebody. The core observation, microscope, electronic microprobe and inclusion temperature and salinity provide three kinds of evidence. Firstly, the heat from the diabase intrusion causes the hardness of the wall rocks, and a great number of new cement mineralsare precipitated from hot fluid flows. Secondly, carbonate veins penetrate strata in handy specimen or under microscope. The clasitc grains in target sandstone are strongly altered by hot fluid flow. Further studies reveal three stages of carbonate minerals: 1 st stage calcite, 2 nd stage ferrous dolomite and 3 rd stage high ferrous dolomite. Thirdly, there are three peaks for the inclusion temperature, 80~90℃, 110~120℃ and 140~150℃, respectively, and three ranges of inclusion salinity 5.0%~10.0%Na Cl,10.1%~15.0%Na Cl and15.1%~20.07%Na Cl. They are in accord with three stages of hot fluid flow processes.

关 键 词：砂岩型铀矿 热流体 蚀变矿物学 包裹体 开鲁盆地 

分 类 号：P619.14[天文地球—矿床学]