【作者】 邵飞；

【导师】 徐恒力；

【作者基本信息】 中国地质大学 ， 环境工程， 2007， 博士

【摘要】 铀是影响当今世界和平与发展的重要战略、能源资源。本世纪前二十年是我国核电高速发展时期,为了确保国家能源安全保障的天然铀充足供应和储备,加强铀成矿作用研究,提升研究水平,建立成矿模式,不仅是当前核地质工作者面临的重大科学问题,而且对指导我国新一轮铀资源勘查的战略部署具重要的现实意义和实用价值。我国铀矿分类习惯于按赋矿围岩而划分,火山岩型铀矿是我国目前已探明的主要铀矿床工业类型之一。尽管赋矿围岩不同,但铀的地球化学性质决定了铀成矿作用在本质上具有共性。铀成矿作用是源—运—聚的动力学过程,流体是贯穿于矿床形成过程中的主要控制因素,水（流体）—岩石相互作用造就了成矿过程。铀成矿作用的研究,以往多是对所观察到的基本地质现象进行归纳和演绎,或是过于偏重分析测试数据的推断,在源—运—聚成矿过程的有机整体中常以“聚”为主要研究对象,缺乏系统性演化和动力学过程研究,在许多问题上得出了众说纷纭的、唯分析测试数据及唯空间定位等的唯象学层次的认识。本文选择中国目前最大、最富的火山岩型铀矿田—相山矿田开展立典性研究。论文以系统科学思想为指导,着重于成矿系统中相互作用和相互依赖的重要要素—源、运、聚的演化和动力学过程分析,提出了火山岩浆期后成矿热液系统概念,认为相山矿田铀成矿作用是火山岩浆期后成矿热液系统演化的产物,铀成矿作用过程与火山岩浆期后热液系统活动相伴随。文章论述了区域地质背景及矿田地质特征;探讨了成矿物质及成矿溶液来源;讨论了成矿期相山火山盆地地下水流动系统及流动形式;在对火山岩浆期后热液系统成矿物质富集、成矿流体运移、成矿物质聚集系统研究的基础上,就成矿流体系统形成和演化的动力学过程进行了分析;最后,建立了相山矿田铀成矿模式,并对矿田深入找矿方向进行了评述。1.相山矿田铀成矿是受制于区域构造环境演化的火山岩浆期后的产物相山矿田铀成矿是在区域地质背景与相山火山盆地特定地质构造环境条件下、火山岩浆期后热液系统中热液（流体）—岩石相互作用动力学过程中一个阶段（时期）的产物,受制于伸展或向伸展过渡的地球动力学背景之下的火山岩浆作用为成矿提供了物质—能量场。研究表明,大规模火山作用之后铀成矿开始发生,其时间跨度延续了50Ma,成矿作用在时间上是一个相对连续的过程。但矿田主成矿期可分为早、晚两期,早期形成碱性钠交代型铀矿化,矿岩时差小;晚期形成酸性萤石—水云母型铀矿化,矿岩时差较大。在空间上,早期铀矿化主要赋存于矿田北部花岗斑岩及其内、外接触带,晚期铀矿化主要赋存于矿田西部火山岩中各级构造及其复合部位。由此可见,相山矿田不同期的高强度成矿作用相应发生于某一时空域内,是与区域构造环境密切相关的、火山岩浆期后热液系统演化的客观产物。2.相山矿田成矿物质来源探讨相山矿田成矿物质来源始终是个有争论的问题。长期以来,在铀源分析的过程中人们往往把目光盯在“汇”区,缺少区域成矿物质迁移过程和历史演化的分析,并以“汇”区各种测试数据推断成矿物质来源。本文基于区域成矿物质时空分布特征,分析了其对铀源的指示意义,同时利用了同位素及微量元素地球化学研究成果探讨矿田成矿物质来源,得出如下结论:（1）区域地层铀含量分布特征及其在地球化学作用过程中的物质迁移变化特征表明,早寒武世地层构成区域铀源层。（2）岩浆岩含铀性具如下特征:相同构造运动期内华南地区重熔型花岗岩铀含量高于同熔型花岗岩铀含量;加里东期及以后的花岗岩体铀含量较高;中生代中酸性火山岩铀含量高于中基性火山岩铀含量。可见,岩浆岩铀含量与成岩物质来源密切相关,区域铀源层的熔融是导致岩浆岩含铀性差异的根本原因。（3）相山中酸性火山岩由深部陆壳物质深熔作用所形成,其铀含量高于区域陆壳平均铀丰度,也高于相山地区震旦纪及中寒武世以后沉积地层的铀含量,结合区域岩浆岩铀含量分布特征,认为区域富铀层位（∈₁）的混染导致了相山火山岩的高铀含量。据此,相山火山盆地是成矿物质的“汇”区,区域富铀层是最根本的成矿物质来源,火山岩浆活动过程是成矿物质的聚集过程,火山岩浆及期后热液是成矿物质迁移的载体。（4）岩、矿石微量元素地球化学特征表明,在铀成矿作用过程中,基底片岩及流纹英安岩提供了部分成矿物质来源。3.相山矿田成矿溶液来源判断成矿溶液的氢、氧同位素组成是判断成矿溶液来源的重要依据。本文认识到流体包裹体是成矿溶液的“化石”,成矿溶液的同位素组成会受到其在演化过程中的水—岩交换、交换时的温度和压力状态、岩石的同位素组成等因素的影响。为此,在了解流体包裹体基本特点的基础上,结合成矿的地质和地球化学特征,对成矿溶液来源进行判断,而不是简单的采用数据对比。（1）相山矿田不同时空阶段成矿流体的化学组分及其盐度、温度及压力值也不相同,早期成矿流体是相对高温、高压、高盐度的流体,而晚期成矿流体的温度、压力和盐度值都相对较低。（2）相山矿田矿前期到矿后期溶液的δ¹⁸O _H2O呈现降低的趋势,这一现象可以解释为大气降水组分越来越多。成矿期溶液的氢、氧同位素组成可分为两组,一组δD约为-60‰,另一组δD约为-80‰,前者对应于萤石—水云母型矿化,后者与钠交代型矿化对应。（3）在雨水、海水和岩浆水三角图中,成矿溶液的氢、氧同位素组成位于岩浆水区域与雨水线之间,而且位于代表赋矿火成岩的岩浆水与雨水组分的连线上。早期成矿溶液的雨水端员的同位素组成是雨水的平均氢、氧同位素组成,而晚期成矿溶液的雨水端员为中生代雨水的氢、氧同位素组成。显然,早、晚期成矿溶液均是岩浆水和雨水的混合,但这并不意味着雨水成因的外生水循环直接进入成矿溶液,只是证明成矿溶液中存在雨水成分。（4）成矿流体的基本特点及成矿溶液的氢、氧同位素组成,表明矿田内不同阶段矿化类型的成矿流体来源不同,结合矿田成矿地质特征认为:早期成矿溶液来源主要是火山岩浆期后热液,其雨水组分源自火山岩浆作用过程中含有元古代、古生代和中生代降水的岩石熔融而进入岩浆,因而其雨水端员表现为雨水的平均同位素组成;晚期成矿溶液来源为原始岩浆发生带—高位岩浆房—火山成因建造结构系统的岩浆期后热液及由于温压降低、冷凝析出的水汽溶液和降水的混合,降水份额比例可能明显大于早期成矿溶液,为此其雨水端员为中生代雨水的同位素组成。4.成矿物质迁移过程分析通过稀土元素地球化学特征研究、蚀变岩中物质迁移的定量计算及水—岩作用地球化学模拟计算,结合成矿物质及成矿溶液来源,分析了前人研究相对薄弱的成矿物质迁移过程。（1）稀土元素地球化学特征表明,由深部古老陆壳物质深熔作用形成的岩浆,在上升途中不仅混染了富铀地层,而且受到高度分馏的结晶作用,由此导致经熔融作用汇集于岩浆中的铀向岩浆演化最晚期热液中迁移,岩浆及期后热液是铀的载体。相山火山岩原始岩浆的铀含量明显高于岩浆库晚期粒间熔浆铀含量,也说明在岩浆演化过程中铀从岩浆向气液转移。（2）蚀变岩中物质迁移的定量计算结果显示,其成矿元素带入及带出的质量变化均不大,这不仅支持了成矿物质来源的分析结论,同时也预示了火山岩浆及期后演化的热液是成矿物质的载体,即成矿物质是经岩浆熔融作用而迁移。（3）将相山火山盆地岩、矿石微量元素组合特征对比,认识到基底片岩及流纹英安岩与岩浆期后热液的相互作用,可能促使其为火山岩浆期后、富含CO₂气体的成矿热液提供了部分铀。成矿温度条件下的水—岩作用地球化学模拟计算结果也表明,富含CO₂气体的流体有利于火山岩及变质岩中铀的迁出。5.成矿期外生地下水以“湍流”运动形式进入成矿溶液自成矿期以来,相山地区构造—水文地质格局未发生根本性的变化。应用重力穿层地下水流动基本理论,刻画了相山地区成矿期古地形控制下的大气降水成因的地下水流场,并勾划了典型剖面成矿期地下水流网。重力势驱动的外生地下水以什么运动形式进入相对高温高压的成矿流体,前人并没有给予解释。本文据成矿流体压力值及汽液包裹体压力值对古地形势驱动的大气降水在对流运动形式下能否进入成矿期流体的古地形分异进行了估算,结果与成矿期古地形势相悖。因而推论成矿期外生地下水进入成矿热液的运动形式是在地形势驱动及岩浆余热及高温高压流体温度、压力梯度驱动下的“湍流”运动。事实上,相山矿田居隆庵矿床深部狭窄空间内不同温、压值包裹体共存,也为外生地下水以“湍流”运动形式进入成矿溶液提供了证据。6.火山岩浆期后成矿热液系统演化促成了相山矿田铀成矿作用基于上述研究,本文提出了火山岩浆期后成矿热液系统概念,认为与区域构造环境演化密切相关的、火山岩浆期后热液系统活动及演化促成了相山矿田长达50Ma的铀成矿作用。（1）成矿物质的富集过程相山火山盆地成矿物质的富集过程包括三个阶段:第一阶段发生于深部陆壳物质形成原始岩浆之时;第二阶段主要发生于高位岩浆房及岩浆的充分演化释放;第三阶段主要是火山岩浆期后几—几十百万年时间内流体（水）—岩石相互作用所导致。第一阶段为相山铀矿田的形成奠定了成矿物质基础,第二阶段是成矿的前奏,岩浆充分演化释放的铀可以为相山早期铀成矿直接提供成矿物质;第三阶段岩浆期后热液系统演化过程中的水—岩作用,促使相山火盆基底地层及流纹英安岩中的铀也向成矿流体进一步富集。（2）成矿流体运移相山火山盆地火山岩浆期后热液活动的主要作用力是热驱动,它来自获得原始岩浆发生带能量补充的高位岩浆房。据相山矿田蚀变带及矿体的空间产出特征、矿体形态特征等综合分析,认为热驱动使得流体的流动为上升流,即成矿流体的运移方向是自下而上的,与火山基底构造相互贯通的火山塌陷构造、断裂构造是成矿流体运移的主要通道,温度梯度是成矿流体运移的主要驱动力,在流体活动中心（流体活动强烈地带）流体压力产生的水压破裂在构造旁侧形成裂隙密集带,为相山矿田矿质沉淀提供了空间。（3）成矿流体系统演化相山火山盆地大规律火山作用后,岩浆演化最晚期热液与岩石相互作用,形成矿前期的水云母化和钠长石化,岩石在发生化学变化的同时,溶液成分也发生了变化,溶液的碱性不断增强,促使Fe³⁺和OH^-化合并导致岩石变红,即发生红化,形成矿岩时差小的铀—赤铁矿型矿石。此后,受原始岩浆发生带—高位岩浆房—火山成因建造系统控制的、含幔源气体成分的火山岩浆期后热液活动性增强,其沿构造通道朝减压（向上）方向运移并发生水压破裂。火山岩浆期后热液与岩石相互作用过程中,由于酸—碱分离形成了上酸下碱蚀变分带,因而在矿田西部目前勘探深度内揭见了成矿时间相对较晚、成矿温度相对较低的富氟酸性成矿流体形成的矿石,即:铀—萤石型及铀—硫化物型矿石。可见,与相山火山岩浆活动有关的流体（水）—岩石相互作用促进了火山岩浆期后成矿流体演化,造就了铀成矿作用过程。7.相山矿田铀成矿模式的建立及深入找矿方向评述据矿田成矿地质特征,考虑成矿作用过程中成矿物质的来源及富集过程、成矿流体系统演化以及成矿流体运移、成矿物质迁移形式和沉淀机理等因素,建立了相山矿田成矿模式并对深入找矿方向进行了评述。成矿模式着重强调了:①相山火山岩成岩过程伴随着成矿物质的富集过程;②早期铀成矿流体由岩浆期后热液与岩石相互作用演化而成,成矿物质主要由岩浆期后热液提供:③晚期铀成矿流体含中生代大气降水成分,流体（水）—岩石作用促使了成矿流体演化,基底变质岩及流纹英安岩也为成矿提供了部分铀源;④陡倾断裂及其两侧裂隙密集带,既是成矿流体运移的通道,也是矿质淀积的场所:⑤相山矿田铀的沉淀主要是流体降温作用、浓缩作用及混合作用等成矿机理耦合的结果。通过对矿田铀成矿作用过程的深入剖析,认为北部和西部仍是今后勘查的重要靶区。北部以寻找花岗斑岩及其内、外接触带控制的早期矿化为主攻方向,加大勘查深度。西部以寻找赋存于火山岩中各级构造及其复合部位的晚期铀矿化为主攻方向,以蚀变场、构造、“湍流”空间域三位一体地段为重要勘查地段;此外,本文依据成矿流体渗透效应引起的酸碱分离,提出在矿田西部要加强探索赋存于花岗斑岩内、外接触带,类似于矿田北部的早期铀矿化,可以对已查明的赋存于火山岩中的酸性铀矿化部位开展攻深勘查。更多还原

【Abstract】 Uranium is an important resource of strategy and energy which influences the peace and development in present world. Nuclear power in our country is rapidly developing during the first 20 years of this century. In order to ensure adequate supply and reserve of natural uranium, enhancing study of uranium metallogenesis, increasing research level and establishing metallogenic modle are not only great scientific problem that nuclear geologists encounter now, but also have important realistic significance and practical value to guide strategical planning of a new round uranium source exploration in China.Uranium deposits in China are used to classified according to host rocks. Volcanic type uranium deposit is one of main industrial types of uranium deposits which are discovered in China. Although host rocks are different, it is basically common that property of uranium geochemistry determines uranium metallogenesis which is a dynamics process of source-migration—accumulation. Fluid is the chief control factor through the whole process of deposit formation. Metallogenic process results from water （fluid） -rock interaction. The previous study on uranium metallogenesis was mainly induction and deduction of basic geological phenomena observed, or excessively emphasis on extrapolation of test and measure data, accumulation was often study object in organic integrity of "source-migration-accumulation" metallogenic process, systematic evolution and dynamics process are merely studied. Conclusions on many problems are obtained on phenomenology which are controversy, based on test data and space position.This paper chooses Xiangshan orefield, the largest and richest volcanic type uranium orefield in China to classical research. The paper is guided under systematic scientific thought, emphasizes evolution and dynamics process analysis of source, migration and accumulation which are key factors in metallogenic system, and puts forward concept of metallogenic hydrothermal solution in post volcanic magma. Metallogenesis in Xiangshan orefield is the product of metallogenic hydrothermal solution system evolution in post volcanic magma, uranium metallogenic process acompanies with activity of hydrothermal solution system in post volcanic magma period. The paper discusses regional geological background and geological characteristics of the orefield, confers sources of metallogenic substances and fluids, discusses flow system and way of underground water in Xiangshan volcanic basin at metallogenic stage. Dynamics process of metallogenic fluid system formation and evolution is analysed on the basis of systematic study on metallogenic substance enrichment, metallogenic fluid movement and metallogenic substance accumulation. Uranium metallogenic model is finally established for Xiangshan orefield, direction for further exploration is reviewed for the orefield.1. Uranium metallogengsis in Xiangshan orefield is product of post volcanic magma constrainted by regional tectonic environment evolutionUranium metallogenesis in Xiangshan orefield is a stage product of hydrothermal solution （fluid）-rock interaction dynamics process in hydrothermal solution system of post volcanic magma at regional geological background and specific geological tectonic environment of Xiangshan volcanic basin. Metallogenic substance-energy field is supplied by volcanic magmatism at earth dynamic background controlled by extension. The research indicates that large volcanism is followed by uranium metallogenesis with time span of 50 Ma. Metallogenesis is a relatively continuous process, but main metallogenesis in the orefield can be divided into two stages. The early stage formed uranium mineralization of alkalic sodium metasomatic type with little time difference between rock and ore, the late stage formed acidic fluorite-hydromica type of mineralization with large time difference between rock and ore. In space, uranium mineralization in early stage is mainly located in granite-porphyry and its both inner and outer contact zones in north orefield, uranium mineralization in late stage is chiefly located into structures and their composites of volcanic rocks in west orefield. Therefore, high-intensity metallogenesis of different stages in Xiangshan orefield correspondingly occurred in same time-space domain, was the objective product of hydrothermal solution system evolution of post volcanic magma which has close relation with regional tectonic environment.2. Discussion of source of metallogenic substances in Xiangshan orefieldSource of metallogenic substances in Xiangshan orefield is always a controversial problem. For long time, analysis of uranium source was focused on accumulation without analysis of migration process and historic evolution of regional metallogenic substance. Various test and measurement data from "accumulation" are induce source of metallogenic substances. On tha basis of temporal and spatial distribution characteristics of regional metallogenic substances, the paper analyzes indication significance of uranium source, discusses metallogenic substance source in the orefield with application of research results of isotope and trace element geochemistry. The conclusions are following:（1） Distribution characteyistics of uranium content in regional strata and variety characteristics of substance migration in geochemistry process show that regional uranium source beds consist of Lower Cambrian.（2） Magmatic rock bearing uranium has the following characteristics: uranium content in anatexis type granite than syntexis type granite in the same tectonic region; uranium content is higher in Caledonian and later granites; Mesozoic intermediate-acidic volcanic rock has higher uranium content than intermediate-basic volcanic rock. It is shown that uranium content in magmatic rock has close relation with source of petrogenic substance. Melting of regional uranium source beds is root reason resulting in uranium content difference of magmatic rocks.（3） Intermediate-acidic volcanic rock in Xiangshan is formed by anatexis of deep continental crust substances which has higher uranium content than average uranium abundance of regional continental crust, is also higher than uranium content of Sinian and Post middle-cambrian strata.Combining with distribution characteristics of uranium content of regional magmatic rock, it is considered that hybrid of regional uranium bearing strata （∈₁） result in high uranium content of Xiangshan volcanic rock. Therefore, Xiangshan volcanic basin is the accumulation area for metallogenic substances, regional uranium source beds are basical source of metallogenic substances, volcanic magmatism is the accumulation process of metallogenic substances, volcanic magma and later hydrothermal solution are migration media of metallogenic substances.（4） Geochemical characteristics of trace elements in both rock and ore show that schist of basement and rhyodacite provide some portions of metallogenic substance source during uranium metallogenesis.3. Determination of metallogenic solution source in Xiangshan orefieldCompositions of H and O isotopes in metallogenic solution are important basis for determination of metallogenic solution source. The paper recognized that fluid inclusion is a "fossil" of metallogenic solution. Isotopic composition of metallogenic solution is influenced by water-rock exchange, temperature of exchange and isotopic composition of rocks, etc. Therefore, determination of metallogenic solution source is based on basic property of fluid inclusion, combined with metallogenic geology and geochemical characteristics, is not simply data correlation.（1） Chemical composition, salinite, temperature and pressure of metallogenic fluid varies at different temporal and spatial stage in Xiangshan orefield. Metallogenic fluid in early stage had relative high temperature, high pressure, high salinity, while temperature, pressure and salinity were relative low in metallogenic fluid in late stage.（2）δ¹⁸O_H2O in solution has tendence of decline from pre-mineralization stage to post-mineralization stage in Xiangshan orefield. This phenomenon is caused by portion increase of meteoric water. Solution isotopic composition of H and O in metallogenic stage can be divided into two groups: one group has about -60%δD, the other -80%δD. The former is corresponding to fluorite-hydromica type mineralization; the later corresponding to sodium metasomatic type mineralization.（3） In triangular diagram of rainwater,seawater and magmatic water, H and O istopic compositions of metallogenic solution are between magmatic water regian and rainwater line, are on alignment representing magmatic water of igneous rock and rainwater. Isotopic composition of rainwater end-member in early metallogenic solution is the average of H and O isotopic composition of rainwater, while rainwater end-member of late metallogenic solution is H and 0 isotopic composition of Mesozoic rainwater. This shows that metallogenic solution of both early and late stages are mix of magmatic water and rainwater, but it does not mean that circulation of epigenic water produced by rainwater did not directly enter into metallogenic solution, it improves that rainwater portion existed in metallogenic solution.（4） Basic property of metallogenic fluid and H、O isotopic compositions of metallogenic solution show that metallogenic fluid sources of mineralization types in different stages are different. Metallogenic solution source in early stage is hydrothermal solution of post volcanic magma, its rainwater portion source is rocks including Proterozoic, Palaeozoic and Mesozoic meteoric water, therefore its rainwater end-member is average isotopic composition of rainwater. Metallogenic solutionsource is mix of hydrothermal solution of primary magma generation Zone-high position magma chamber-volcanic construction system and meteoric water, water-gas solution condensed due to temperature and pressure decrease, portion ratio of meteoric water may be obviously larger than metallogenic solution of early stage because rainwater end-memberi is Mesozoic rainwater isotopic composition.4. Analysis of metallogenic substance migration processMetallogenic substance migration process is analyzed by study on REE geochemical characteristics, quantitative calculation of substance migration in altered rock and geochemical simulation calculation of water-rock interaction, combining with source of metallogenic substance and solution.（1） REE geochemical characteristics indicate that in the upward-risen way magma formed by anatexis of deep older continental materials did not only mix with uranium bearingstrata, but also had crystallization of high intensive differentiation which results in uranium migration from magma to latest hydrothermal solution. Magma and the later.hydrithermal solution are media of uranium. Uranium content in preliminary magma of Xiangshan volcanic rock is obviously higher than in magma of magmatic chamber. This shows that uranium transfers from magma to gas and liquid during magmatic evolution.（2） Quantitative calculation result of substance migration in altered rock demonstrates that quantity of inflow and outflow of metallogenic elements varies little. This supports the analyse conclusion of metallogenic substance source, also indicates that volcanic magma and later hydrothermal solution are media of metallogenic substance, which migrates in magmatic dissolution.（3） REE association characteristics correlation of rock and ore in Xiangshan volcanic basin shows that interaction of basement schist and rhyodacite with hydrothermal solution of post magma can provide some uranium for metallogenic hydrothermal solution with rich CO₂ gas in post volcanic magma. Geochemical simulation calculation result of water-rock interaction at temperature condition of metallogenesis also shows that fluid with rich CO₂ gas conduces to uranium migration from volcanic rock and metamorphic rock.5. Epigenic groundwater enters into metallogenic solution in "turbulence" movement way during metallogenic stageTectohydrogeological frame has not basically changed in Xiangshan area since metallogenic stage. With application of basic theory of gravity penetrating groundwater flow, groundwater flow field originated from meteoric water and controlled by palaeotopography at metallogenic stage in Xiangshan area is specified, groundwater flow net at metallogenic stage in typical section is also described.What kind of movement way did epigenic groundwater driven by gravity potential enter into metallogenic fluid with relative high temperature and high presure? There was no explanation for it. Can meteoric water driven by palaeotopographic potential enter into metallogenic fluid in convectional movement way?The paper calculates differentiation of the palaeotopography according to pressure value of metallogenic fluid and pressure value of gas-liquid inclusion, the result is contradictory to the palaeotopography at metallogenic stage. So it is conferred that movement way in which epigenic groundwater enters into metallogenic solution at metallogenic stage is "turbulence" movement driven by topographic potential, magmatic residual heat and gradients of temperature and pressure of high temperature and high pressure fluid. In fact, inclusions with different temperature and pressure valves coexist together in a deep and very small room in Julongan deposit of Xiangshan orefield. This also provides evidence that epigenic groundwater enters into metallogenic solution in "turbulence" movement.6. Uranium metallogenesis in Xiangshan orefield results from systematic evolution of metallogenic hydrothermal solution in post volcanic magma stageIn this paper, concept of metallogenic hydrothermal solution system in post volcanic magma is put forward on the basis of above researches. Uranium metallogenesis with a period of 50 Ma in Xiangshan orefield result from evolution and activity of hydrothermal solution system in post volcanic magma and in close relation with evolution of regional tectonic environment.（1） Enrichment process of metallogenic substance in Xiangshan volcanic basin consists of 3 stages: the first stage occurred when deep continental materials formed primary magma; the second stage occurred at full evolution and relief of magma and upper magmatic chamber; the third stage resulted from fluid （water） -rock interaction of several or dozens Ma in post volcanic magma. Metallogenic substance basis of Xiangshan orefield was established in the first stage. The second stage was the prelude to metallogenesis, uranium released by full evolution of magma can directly provide metallogenic substance for the early uranium metallogenesis in Xiangshan; in the third stage ,water-rock interaction in evolution process of post volcanic magma caused uranium from basement strata and rhyodacite in Xiangshan volcanic basin further enriching in metallogenic fluid.（2） Metallogenic fluid migration main force of hydrothermal solution activity in post volcanic magma in Xiangshan volcanic basin is driven by thermo which came from upper magma chamber where energy from primary magma generation was refilled. Based on comprehensive analysis of characteristics of alteration zone, orebody spatial distribution and forms, thermal drive is considered to force fluid into upwelling , motion direction of metallogenic fluid is from down to up, volcanic collapse structure and fault structure interconnecting with volcanic basement structure are main channel for metallogenic fluid migration, temperature gradient is chief driving force for metallogenic fluid migration. The space for mineralised material precipitation in Xiangshan orefield is provided by dense fractures in sides of a fault cracked by water pressure generated by fluid pressure.（3） Evolution of metallogenic fluid system after large volcaniosm in Xiangshan volcanic basin, the latest hydrothermal solution in magmatic evolution interacts with rocks to form hydromicazation and albitization. While rock chemically changes solution composition varies, alkali in solution increases to combine Fe³⁺ with OH^-, so rock becomes red to form U-hematite type ore with little time difference between ore and rock. Then activity of hydrothermal solution with mantle-derived gas composition in post volcanic magma enhances, the hydrothermal solution migrates upward along fault channel, water pressure cracks. Acid-alkali separation results in alteration zoning of upper acid and lower alkali. U-fluorite type and U-sulfide type ore formed by metallogenic fluid with rich fluor acid in relative low temperature and late time of metallogenesis in west orefield. So interaction of rock-fluid （water） which is close relation with volcanic magmatism facilitates evolution of metallogenic fluid in post volcanic magma, and produces process of uranium metallogenesis.7. Establishment of uranium metallogenic model and discussion of further exploration direction in Xiangshan orefieldMetallogenic model is established and further exploration direction is discussed in Xiangshan orefield on basis of metallogenic geological characteristics of the orefield, source and enrichment of metallogenic substance in metallogenic process, systematic evolution and migration of metallogenic fluid, migration mode and precipitation mechanism of metallogenic substance, etc.The metallogenic model emphasizes:①Valcanic diagenetic process in Xiangshan accompanies enrichment process of metallogenic substances;②Early uranium metallogenic fluid is formed by interaction of rock with hydrothermal solution of post magmatism, metallogenic substances are provided by hydrothemal solution of post magmatism;③Late uranium metallogenic fluid contains composition of Mesozoic meteoric water, fluid （water） -rock interaction promotes evolution of metallogenic fluid, basement schist and rhyodacite also provide some uranium source for metallogenesis;④High-angle fault and its lateral zones of dense fractures are not only migration passage of metallogenic fluid, but also room for precipitation of metallogenic substances;⑤Uranium precipitation in Xiangshan orefield is coupling result of metallogenic mechanism of fluid cooling, concentrating and mixing, etc.Through deep analysis of metallogenic process, north and west of Xiangshsn orefield are considered as important targets for exploration in the futune. Main efforts and deep exploration are focused on early mineralization controlled by granite-porphyry and its both inner and outer contact zones in north of Xiangshan orefield. Main efforts are focused on late uranium mineralization locating within all kinds of structures and their conjuctions. The spatial trinity of alteration field, structure and "turbulence" is important area for exploration. Moreover, according to acid-alkali separation caused by permeation effect of metallogenic fluid, this paper puts forwart that exploration should be strengthened in inner and outer contact zones of granite-porphyry in west of xiangshan orefield to look for early uranium mineralization, similar to north of Xiangshan orefield. The exploration shall go further in depth for acidic uranium mineralization positions discovered in volcanic rock.更多还原