摘要
针对中国南方最重要的砂岩型铀成矿区带——滇西腾冲地块新生代盆地群,目前正在实施的新一轮调查已取得显著进展。尤其是在龙川江盆地南部钻探发现新的工业矿体,为成矿机制研究和探索勘查方向提供了宝贵素材。鉴于滇西成矿带特殊的"构造-赋铀岩相-成矿驱动"特征,开展矿体铀赋存状态研究,对于追溯铀源区、重建叠加成矿过程、建立找矿标志和矿床开发利用都具有重要意义,但相关报道鲜见。本文利用ICP-MS、电子探针定量分析和高分辨扫描电镜等手段,对龙川江盆地南部团田地区最新钻获的矿体岩心开展铀赋存状态分析。结果表明,该地区铀矿物以铀石为主,存在铀钍石、独居石等含铀矿物。铀矿物主要以微细粒侵染状赋存于填隙物处、吸附于碎屑矿物表面,少数以铀石微粒集合体形式赋存于蚀变黑云母、石英等矿物颗粒的裂隙中。面扫描影像显示出矿化段铀元素与钍、稀土元素钇具有正相关的分布特征,指示龙川江盆地团田地区砂岩型铀矿体物源区岩石Th、稀土元素Y含量可能具有较高本底值,对于追索物源区具有一定指示意义。龙川江盆地铀源供给存在多源性、多期性可能。
About south China's most important sandstone-type uranium mineralization belt,Tengchong block group of cenozoic basin in Western Yunnan,great progress has been made in a new survey.Especially in southern Longchuanjiang basin,drilling a new industrial ore bodies,for the study of the metallogenic mechanism and provided the precious material exploration prospecting direction.In view of the Western Yunnan Metallogenic belt special"tectonics-uranium-lithofacies-ore-forming",to trace uranium source area,rebuild superimposeed mineralization process,establishing ore-prospecting criteria and deposit exploitation and utilization has important significance,but rarely seen reports.The technology of ICP-MS,EMPA and high-resolution SEM were applied in this research to analyze the rock of mineralization area in Tuantian Township.The analytic data show that coffinite is the main uranium mineral in this area,with some uranium bearing minerals(horite and monazite) existing in there.These minerals are existing in the form of micro grain and infection status in the interstitial material and absorbing on the surface of detrital minerals.A part of minerals exist in the fissure of alteration biotite and quartz granule in the form of uranium particle assembly.The images of area scanning show that the distribution characteristic of uranium element has positively correlation with thoriumm and Yttrium element in the mineralization area.It indicates the sandstone type uranium deposit in Tuantian Longchuanjiang Basin,that Th,rare earth element Y content may have higher background value,to recover the provenance has a certain instruction significance.The supply of uranium source in Longchuanjiang Basin may have multiple sources and multiple phase.
引文
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