摘要
牟定1101铀矿区是康滇地轴中南段发现高品位、巨粒晶质铀矿代表性产地之一.为了解铀矿物的形成时代及成因,利用微区、原位分析技术(EPMA、SEM、LA-ICP-MS)对该区3件沥青铀矿样品开展了主量化学成分、稀土元素分析及年龄测定.沥青铀矿电子探针(EPMA)化学成分具有高PbO、ThO2、Y2O3,低SiO2,Na2O,CaO,K2O,ZrO2含量特征,反映沥青铀矿形成之后遭受后期的蚀变、改造作用较弱.沥青铀矿的稀土元素ΣREE-(U/Th)、ΣREE-(ΣREE/ΣREE)N图解表明其为岩浆作用相关成因、形成于高温环境(T>450℃).3件沥青铀矿的U-Pb同位素年龄在(950±5 Ma、MSWD=0.025,953±9 Ma、MSWD=0.051,954±8 Ma、MSWD=0.085)之间,表明它们具有相近的形成时代(新元古界晚期).对比国外不同类型铀矿床,该区的铀成矿作用具有岩浆成因特征.新元古界晚期,Rodinia超大陆由聚合转化为裂解阶段,广泛引起了Pt1j苴林群发生区域变质、混合岩化、铀成矿作用.牟定1101铀矿区的成矿作用与~960 Ma Rodinia超大陆裂解地质事件所对应的晋宁构造运动有关.
The 1101 uranium ore area is one of the representative uranium deposits,which has high-grade and larger uraninite.In order to know the genesis and metallogenic age of the pitchblende,the in-situ analytical technologies(EPMA、SEM、LA-ICP-MS)was applied to analyze the three pitchblende samples.The chemical composition of EPMA indicate that pitchblende exhibits high contents of PbO,ThO2,Y2O3and low SiO2,Na2O,CaO,K2O,ZrO2,which shows that it has suffered less alteration after crystallization.The REE diagram of(ΣREE-(U/Th),ΣREE-(ΣREE/ΣREE)N)reflects that these pitchblend crystalized in the condition of magamatic process,related to a high temperature environment(T>450℃).The LA-ICP-MS of pitchblende U-Pb dating yields the age of(950±5 Ma,MSWD=0.025,953±9 Ma,MSWD=0.051,954±8 Ma,MSWD=0.085),providing the metallogenic age constraint on the 1101 uranium ore area(Late-Neoproterozoic).Compared with different types of uranium deposits abroad,the 1101 uranium ore was of magamatic origin that had undergone the process of migmatization.The Rondinia super continent was in the transition from convergence to split at the period of Late-Neoproterozoic,which led to the Pt1j strata generated regional metamorphism,migmatization and uranium mineralization.The metallogenic age ca.960 Ma of 1101 uranium deposit corresponds to the Jinningian tectonic movement,which belongs to the Rondinia supercontinenal spilitting geological event.
作者
武勇
秦明宽
郭冬发
蔡煜琦
王凤岗
吴玉
郭国林
刘章月
Wu Yong;Qin Mingkuan;Guo Dongfa;Cai Yuqi;Wang Fengang;Wu Yu;Guo Guolin;Liu Zhangyue(CNNC Key Laboratory of Uranium Resources Exploration and Evaluation Technology,Beijing Research Institute of Uranium Geology,Beijing 100029,China;Analytical Laboratory,Beijing Research Institute of Uranium Geology,Beijing 100029,China;Fundamental Science on Radioactive Geology and Exploration Technology Laboratory,East China University of Technology,Nanchang 330013,China)
出处
《地球科学》
EI
CAS
CSCD
北大核心
2020年第2期419-433,共15页
Earth Science
基金
中核集团启明星项目(No.2018(294))
国防预研项目(No.3210402)
中国地质调查局项目(No.DD2016013628)
中国核工业地质局项目(Nos.201713,201653).
