【摘要】 本文以粤北长江铀矿区棉花坑铀矿床的横向矿化蚀变剖面为研究对象,系统研究了代表性新鲜花岗岩、蚀变岩和矿石的主量、微量以及稀土元素地球化学特征,运用质量平衡计算方法探讨了各蚀变带组分的迁移规律,以期解决成矿物质来源、成矿流体来源及其性质等问题。结果表明,该矿化蚀变剖面具有明显的水平分带特征,可分为新鲜花岗岩带（Ⅴ带）、远矿碱交代蚀变带（Ⅳ带）、近矿绿泥石化蚀变带（Ⅲ带）、矿旁水云母化蚀变带（Ⅱ带）和矿化中心赤铁矿化蚀变带（Ⅰ带）。从侧缘碱交代带→矿化中心带,Si O2的带入率（0. 27%→0. 21%→0. 50%→0. 70%）整体上与U的带入率（4. 73%→8. 07%→39. 26%→98. 29%）呈正比,K+与Na+相互排斥呈现"钾钠不相容"现象,Mg O与Mn O呈现出"此消彼长"的迁移特征,是对流平衡迁移方式的表现。Th、Pb、Cs、Mo、As元素在矿化中心带的带入率最大,Ba、Sr、Co、V元素在矿化中心带迁出率最小,这对铀成矿（铀矿化）具有很好的指示作用。根据各蚀变带元素的含量、比值及迁移特征,结合前人的研究成果,认为矿床的成矿物质主要来源于赋矿围岩长江岩体,成矿流体在成分上富含挥发分和矿化剂（CO₂、F、H₂O等）、碱金属元素（K、Cs、Rb）和重稀土元素,性质上具相对高的氧逸度,其来源是地幔流体与经历了深循环大气降水的混合成因流体。挥发分和矿化剂（CO₂、F、H₂O等）的带入是矿床重要的矿质迁移机制,CO2的逸出伴随着氧化向还原过渡的环境是矿床重要的矿质沉淀机制。更多还原

【Abstract】 In this paper,the major,trace and rare earth elements of representative fresh samples of granites,altered rocks and ores were studied from the mineralization-alteration cross section in Mianhuakeng uranium deposit,northern Guangdong Province. Using the method of mass balance calculation,the migration law of components in each alteration zone was discussed to solve the problems of the source of ore-forming materials,source of ore-forming fluids and their properties. The results show that the mineralization-alteration cross section has obvious horizontal zoning characteristics,which can be divided into the fresh granite zone（ Ⅴ）,the alkali metasomatic alteration zone（ Ⅳ）,the chloritization alteration zone（ Ⅲ）,the hydromicatization alteration zone（ Ⅱ） and the hematitization alteration zone（Ⅰ）. From the lateral alteration zone（ the alkali metasomatic zone） to the central mineralization zone（ the hematite alteration zone）,the immigration rate of SiO₂（ 0. 27% →0. 21% →0. 50% →0. 70%） was positive to the immigration rate of U element（ 4. 73% →8. 07% →39. 26% →98. 29%）. K+and Na+were mutually exclusive and incompatible,Mg O and Mn O exhibit a negative relationship,which might show a balanced convection migration. Th,Pb,Cs,Mo and As elements have the highest immigration rate in the central mineralization zone,while Ba,Sr,Co and V elements have the lowest migration rate in the central mineralization zone,which could be used as a good indication for uranium mineralization. According to the content,ratio and migration characteristics of the elements in each alteration zone and combine to the previously published data,it is considered that the ore-forming materials of the deposit are mainly contributed by the host rock,the Changjiang granite. The ore-forming fluids were rich in volatiles and mineralization agents（ CO₂,F,H₂ O,etc.）,alkali metals（ K,Cs,Rb） and HREE with relatively high oxygen fugacity,and its sources were a mixture of mantle fluids and meteoric waters during the deep circulation. The introduction of volatiles and mineralization agents were the important mechanism for mineral migration of the deposit,and the environment from oxidation to reduction with CO₂ escape was an important mechanism for mineral precipitation of the deposit.更多还原