【作者】 乔海明；

【导师】 张复新；

【作者基本信息】 西北大学 ， 地球化学， 2006， 博士

【摘要】 该项目属中国核工业地质局“十五”整装科研项目。为铀矿地质生产中科研项目。在野外地质调查，样品采集和分析、数据处理和综合的基础上，本文系统的分析吐哈盆地十红滩铀矿床容矿主岩的后生蚀变地球化学、同位素地球化学、地下水地球化学、有机地球化学和生物地球化学特征。认为容矿层岩石来源于南部觉罗塔格山，源岩类型主要为花岗岩，各地球化学分带的岩石具有相同物源和构造环境，均形成于被动大陆边缘，为低温成岩成矿作用的产物；有机质、生物参与了早成岩作用和表生成岩作用。在吐哈盆地西南缘弱挤压的构造环境下，在流体—有机质—生物的作用下，容矿主岩具有明显的地球化学水平分带性，依次可分为氧化带、弱氧化带、氧化还原过渡带和还原带。这一分带通过岩石的结构构造、颜色、蚀变矿物、常量元素含量、稀土元素含量以及U、Tu／U、Ra、S和有机质含量、微生物种群和数量等的规律性变化表现出来。通过水的离子成分、稀土元素组成和氢氧同位素等分析了含矿含水层地下水性质和来源，认为现代成矿流体属于外生流体，来源于南部的觉罗塔格山基岩裂隙水。地下水在含水层中径流过程时，在生物、有机质的作用下，发生了脱硫酸作用，形成具自生流体性质的强还原气体CH₄、H₂和H₂S等。有机质的镜质体反射率、干酪根原子比和碳同位素研究认为，容矿层有机质的母质类型为含腐泥腐殖型，其演化处于暗褐煤与亮褐煤阶段，生烃模式处于生物化学生气阶段。容矿层岩石中的酸解吸附烃、可溶有机物和铀之间有明显的正相关关系，具有厌氧细菌的改造特征。不同地球化学环境岩石微生物的培养鉴定，结合室内微生物对铀的模拟氧化实验和还原实验不仅直接证明微生物能在含有剧毒、高含量铀的矿石中生存和繁殖，促使层间氧化带的发育和铀的溶解迁移，而且可以利用有机质的微生物降解作用形成的烃类作为其生长的碳源，通过生物地球化学作用，在直接促使铀的还原沉淀同时，改变流体的Eh—pH，导致铀的还原成矿和吸附成矿，控制了该矿床铀的富集成矿和定位。这一结论丰富了我国层间氧化带砂岩型铀矿床成矿理论，在含油气盆地进行层间氧化带砂岩型铀矿找矿、地浸开采、环境治理方面具有重要的实践意义。容矿层有机质生物标志化合物和矿床地质特征的研究，结合国外典型层间氧化带型铀矿床的形成条件和模式分析，认为在该矿床形成过程中发挥重要作用的烃类属于同生还原剂，并非来源于上覆煤层和邻近油气田，明确了在吐哈盆地铀与煤、天然气、油是同一盆地不同部位的共存能源。提出了艾丁湖斜坡带上的中侏罗统西山窑组辫状河砂体是该区矿床铀矿勘查的重点层位，在具体实践中应重视局部构造的研究和钻孔中与层间氧化带有关的矿化信息的研究，这样可以达到扩大找矿、提高找矿效益目的。该研究成果在矿床勘查中得到验证，并取得良好的找矿成果，新发现铀工业孔4个，新增铀资源量XXXX吨。本文的创新点为：1、首次把流体—有机质—生物成矿理论用于层间氧化带砂岩型铀矿床。以微生物为纽带，研究了具有外生流体性质的渗入地下水和自生流体性质烃类之间的相互关系及在铀矿床形成过程中的作用。2、在国内首次从层间氧化带砂岩型铀矿床容矿层岩石中培养出不同代谢特征的微生物种群。首次采用培养出的微生物成功的进行了铀的氧化实验和铀的还原沉淀实验。3、在国内首次把有机地球化学方法用于研究层间氧化带砂岩型铀矿床容矿层有机质的构成、演化以及在矿床形成过程中的作用。证明了油气在砂岩型铀矿床成矿过程中发挥了重要的作用，这对于在含油气盆地寻找可地浸砂岩型铀矿床具有重要的意义。更多还原

【Abstract】 This research project is scientific research project in uranium geology production which was approved to carry out by China nuclear industry geology bureau.On the basis of geological investigation in the field, sampling, samply analysising, simulated test , data processing, inductive and synthesize, the report analysed in a systematic way epigenetic alteration geochemical , isotope geochemical, hydrogeochemical, organic geochemical, organism geochemical characteristic of ore-locating hosting rock in the Shihongtan uranium deposit in Turpan-Hami basin. The author thinks that ore-locating hosting rock originated from southern Jueluotage mountain, the precursor type is mainly granite. the rock in different geochemical belt is same in provenance and tectonic environment. The rock was formed in edge of passive continent, and is product of law-temperature diagenesis action. Organic matter and organism participated in early diagenesis action and epidiagenetic metallogenesis. In weak compression tectonic environment of southwest Turpan-Hami basin, the geochemical horizontal zonation was formed in the ore-locating hosting rock by organism-organic matter-fluid mutual action. The zonation is divided into completely-oxidized, incompletely-oxidized, redox and primary zone in proper order. The zonation was expressed in regularity variation of rock texture and structure, colour, altered mineral, major elements, Ree, U, Th/U, U/Ra, S, organic matter, microbial species and quantity. The nature and source of groundwater in ore-bearing aquifer is analysed by means of major ion composition , Ree andδ¹³OδD, author think that present metallogenetic fluid is exogene origin , and origined from bed rock crevice-water of Jueluotage mountain. When groundwater runoffs in aquifer , the sulphate reduction reaction took place and strong reduced gas H₂S, CH₄, H₂ were formed by way of organism and organic matter mutual interaction. Through study on vitrin reflection power, H/C, O/C, carbon isotope of kerogen, the author think that organic matter mother-material type is sapropelic humus. organic matter is under attritus and bright brown coal stage. Hydrocarbon-generation model is biochemical gas-generation stage. Uranium content in rock is positive correlativity with soluble organic, acidolysis hydrocarbon. The microbial in different geochemical environment of rock culured and distinguished, in addition, microbial oxidation and reduction uranium simulated test proved that microbial may not only live and breed in poisonous and high content uranium ore, imple layer oxidation zone to develop and uranium to dissolve and migrate, but control uranium concentration to form deposit and place by way of biological geochemical impling uranium to reduct and precipitate by changing Eh—pH of fluid which use hydrocarbon origined from organic matter biological decomplexation as carbon resourse. This conclusion enriches metallogenetic theory of layer oxidation zone sandstone type uranium deposit, but has important practical significance in finding this kind of deposit, in-situ leach and environment harness. According to studying on biological marke chemical compound, deposit geological feature of this deposit, as well as formation condition and model of typical layer oxidation zone sandstone type uranium deposit abroad, the paper think that hydrocarbon belongs to contemporaneous reductive, does not origined from upper coal- seam and oil-gas field close to this uranium deposit, which play important role in metallogenetic process, clear that uranium deposit and coal, gas-oil is coexitence energy resources in different place of identical basin. Author poses that braided river dene in the middle Jurassic Xishanyao formation is key position for uranium exploration in the Ai-ding lake belt, must attach importance to study on local structure and mineralized information relation with layer oxidation zone, like this, goal of enlargement prospecting and the enhancement for prospecting benefical may be achieved. The result of study were proved in deposit exploration, the good ore-searching result was obtained. four commercial mineralized holes were new found. the uranium amount of resources increased xxxx tons.更多还原