下庄铀矿田白水寨花岗岩特征与铀成矿作用研究

发布时间：2018-06-17 12:18

本文选题：白水寨花岗岩 + 岩相学　；参考：《东华理工大学》2015年硕士论文

【摘要】：白水寨花岗岩位于下庄矿田西北部,地表出露面积约2km2,处于多期次成矿热液活动中心叠加部位。本文从岩相学、岩石地球化学等方面重点对白水寨花岗岩进行系统研究,分析其构造环境和成因,同时分析研究区控矿构造特征、围岩蚀变特征、围岩蚀变与铀成矿关系,探讨白水寨花岗岩、岩石地球化学特征、铀矿化及成矿作用。白水寨花岗岩具有高硅、高钾、高铝、富碱、低铁镁比值,具有S型强过铝质花岗岩特征;微量元素特征表现轻稀土富集、重稀土亏损特征;白水寨岩体的CaO/Na2O平均比值均大于0.3、TFeO+MgO+TiO2含量为2.09%~3.06%,都低于4%,反映其源岩以泥质成分为主,在Rb-(Y+Nb)构造环境判别图解中白水寨花岗岩表现为后碰撞构造属性,说明白水寨岩体的形成可能是在地壳运动过程中,通过古元古代变质沉积岩低程度部分熔融形成,经过印支后碰撞运动使地壳缩短减薄侵位加上地幔上涌形成的花岗岩。白水寨花岗岩主要受北东向构造、北东东-北东向及北西西-近东西向三组构造控制其展布,以北东东-北东向和北西西-近东西向构造控矿。岩体发育硅化、钾长石化、碱交代、绢云母化、绿泥石化、赤铁矿化、黄铁矿化、萤石化等多种热液蚀变;矿石矿物主要有沥青铀矿、铀石、钛铀矿、钍石等原生铀矿物和硅钙铀矿、钙铀云母、铜铀云母等次生铀矿物。研究区岩浆活动—断裂构造—铀矿化组合分为三期:第一期富铀热液活动形成于晚期细粒花岗岩侵入之后,早阶段为高温富硅酸性热液,矿化类型主要为铀-微晶石英型;在此基础上,第二期中温富铀碱性热液形成碱交代岩,矿化类型主要为铀-碱交代-赤铁矿型和铀-微晶石英-黄铁矿型;第三期中低温富硅、铀酸性热液活动形成于中基性岩浆,矿化类型主要为铀-微晶石英型。与铀成矿关系密切的绿泥石化以铁绿泥石、铁镁绿泥石及密绿泥石为主,形成温度介于172.81℃~228.49℃,平均为202.08℃;成矿过程中高温热液使得造岩矿物云母、长石蚀变成绿泥石并活化铀,在后期还原条件下新生蚀变矿物吸附铀。白水寨花岗岩在岩浆演化过程中铀向晚期形成岩体富集,铀矿化发生于岩体接触带和岩体与断裂构造的结点处,其燕山早期花岗岩浆形成了铀活化区,燕山晚期第三阶段高铀、极低钍超酸性花岗岩浆侵入,形成研究区内高铀花岗岩;在蚀变断裂内水-岩作用催化之后,形成早期蚀变矿物,使岩石中惰性铀释放出来成为活性铀;大气降水浸取了活化铀,富碱含挥发组分CO2和F的催化剂热液流体上升产生复合作用,热液中的活性铀在还原环境下形成铀矿物,并被新生成的蚀变矿物吸附;通过北东向断裂带聚集、传导、运输、存储,然后与近东西向复杂构造带和北东东向构造带及补体相交接,从而形成白水寨地区铀矿床和铀矿点。
[Abstract]:The Whitewater Village granite is located in the northwest of the lower Zhuang ore field. The surface area of the surface is about 2km2 and is located at the superposition of the multi-stage hydrothermal activity center. This paper systematically studies the white water village granite from petrography, rock geochemistry and other aspects, analyzes its tectonic environment and causes, and analyses the characteristics of ore control structure and the alteration of surrounding rock. Characteristics, the relationship between wall rock alteration and uranium mineralization, and discuss the Whitewater Village granite, rock geochemistry, uranium mineralization and mineralization. Whitewater Village granite has high silicon, high potassium, high aluminum, alkali rich, low iron and magnesium ratio, with the characteristics of S type strong peraluminous granite; trace element characteristics show light rare earth enrichment, heavy rare earth loss characteristics; Whitewater Village rock mass The average ratio of CaO/Na2O is more than 0.3, and the content of TFeO+MgO+TiO2 is 2.09%~3.06%, which is lower than 4%. It reflects that the source rock is mainly composed of argillaceous composition. In the Rb- (Y+Nb) tectonic setting diagram, the Whitewater Village granite is manifested as the post collision structural property. It is said that the formation of the rock mass may be in the process of crustal movement through Paleoproterozoic metamorphic deposition. The low-level partial melting of rock formed, after the collision movement of the Indo branch, the crust shortened the thinning emplacement and the granites formed by the upwelling of the mantle. The Whitewater Village granite is mainly North East structure, the north east east to the North East and the North West West East-West structure control its distribution, and the north east east to North East and West West West near East-West structure ore control. Silicification, potassium long fossilization, alkali metasomatism, sericite, green mud petrochemistry, hematite mineralization, pyrite mineralization, fluoro petrochemistry and other hydrothermal alteration, ore minerals are mainly primary uranium ore, uranium ore, uranium tiorite, thorium and other primary uranium minerals, calcium uranium mica, copper uranium mica and other secondary uranium minerals. The magmatic activity fracture structure in the study area - The uranium mineralization assemblage is divided into three stages: the first phase of uranium rich hydrothermal activity was formed after the invasion of late fine-grained granites. The early stage was high temperature silicon rich acid hydrothermal solution, and the mineralization type was mainly uranium microcrystalline quartz type. On this basis, the second phase medium temperature uranium rich alkaline hydrothermal solution formed alkali metasomatism, and the mineralization type was mainly uranium alkali metasomite type and uranium. Microcrystalline quartz and pyrite type; third stage low temperature silicon rich, uranium acid hydrothermal activity formed in medium base magma, mineralization type is mainly uranium microcrystalline quartz type. The green mudstone, which is closely related to uranium mineralization, mainly consists of iron chlorite, iron magnesia chlorite and millistone, and the formation temperature is 172.81 ~228.49 C, average 202.08 degrees C; Medium and high temperature hydrothermal fluids make rock formation mineral mica, feldspar alteration to chlorite and activate uranium, and activate uranium and adsorb uranium in the later reduction conditions. The Whitewater Village granite is enriched in the late stage of magma evolution, and uranium mineralization occurs at the contact zone of rock mass and the junction of rock mass and fracture structure, and its early granite in Yanshan The uranium activation area, high uranium in the late third stage of Yanshan, extremely low thorium super acid granite magma invaded and formed high uranium granite in the study area. After the alteration of internal water and rock catalysis, the early altered minerals were formed to release the inert uranium from the rock into active uranium, and the atmospheric precipitation soaked the activated uranium, and the alkali rich contained the volatile component CO2. The active uranium in the F catalyst has a compound effect. The active uranium in the hydrothermal solution forms uranium minerals in the reductive environment and is adsorbed by the newly formed altered minerals; it aggregates, conducts, transport, and stores through the north-east fault zone, and then connects with the near East-West complex tectonic zone and the North East to East tectonic belt and complement, thus forming the Whitewater Village. Area of uranium and uranium deposits.
【学位授予单位】：东华理工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：P619.14;P588.121

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