【作者】 韩超；

【导师】 张国宾； 杨帆；

【作者基本信息】 辽宁工程技术大学 ， 矿产普查与勘探， 2021， 硕士

【摘要】 迪彦钦阿木钼矿床位于西伯利亚板块东南陆缘增生带,东乌旗-扎兰屯火山型被动陆缘东乌旗褶皱带内,先后经历了古亚洲洋闭合、古太平洋板块俯冲、中亚造山等构造活动,成矿地质条件良好,是近年来发现的超大型钼矿床之一。本文在野外地质调查与室内研究基础上,通过锆石U-Pb同位素年代学、岩石地球化学等分析测试手段,厘定成岩成矿时代,分析成矿地质构造背景与矿床成因,为矿区深部及外围找矿提供理论指导,同时为国内外地质工作者寻找类似矿床提供借鉴。论文研究取得的进展与成果如下:迪彦钦阿木钼矿体赋存于侏罗系上统查干诺尔组安山岩和凝灰岩中,在水平面上呈环状,矿体四边相对平直,交汇处呈弧形的环形分布;在剖面上呈筒状向下延伸,矿体上缓下陡,向内倾斜,在深部有向岩体收缩的趋势。矿体东西长2.5km,南北长2km,平均品位为0.097%,钼金属量为77.8万吨,钼矿化类型主要有团块状、浸染状、网脉浸染状。围岩蚀变发育,由内向外依次为硅钾化、黄铁绢英岩化、青磐岩化、泥化。LA-ICP-MS锆石U-Pb同位素测试结果表明,成矿相关的二长花岗斑岩和碱长花岗斑岩的²⁰⁶Pb/²³⁸U加权平均年龄分别为158±1.8Ma和158±2.0Ma,与矿体中辉钼矿样品的Re-Os年龄（157±2.8Ma）基本一致,且略微早于辉钼矿成矿年龄,表明二长花岗斑岩、碱长花岗斑岩与辉钼矿体形成于同一次构造岩浆活动时期,成岩成矿时代为晚侏罗世。岩石地球化学分析结果表明,二长花岗斑岩和碱长花岗斑岩均具有富硅、贫铝、高碱、高钾、低钙的特征,为过铝质高钾钙碱性岩石系列,轻稀土富集,重稀土亏损,具较强的铕负异常,无铈异常,富集Rb、Th、U、Sm、K等元素,亏损Ba、Sr、P、Ti等元素,具有较高的Rb/Sr、Nb/Ta、Zr/Hf比值,为A2型花岗岩,形成于蒙古-鄂霍次克海闭合挤压构造环境向闭合后伸展构造环境转换阶段。迪彦钦阿木钼矿床成矿流体初始温度具有高温、高盐度、高氧逸度的特征,成矿物质主要来源于深部的酸性岩浆热液,为典型的斑岩型钼矿床。矿床具有低Mo,少CO₂包裹体、高Na,高Cl的特征,属于Endako型斑岩型钼矿床。中生代晚期,加厚的岩石圈发生拆沉,富含成矿物质和挥发分的酸性岩浆上涌,在浅地表快速冷凝结晶形成斑状花岗岩体,岩浆房深部的成矿热液沿着次级的断层和裂隙上升,与附矿围岩发生接触交代作用,成矿流体发生二次沸腾作用,钼元素平衡状态被打破沉淀析出,形成迪彦钦阿木钼矿床。该论文共有图19幅,表9个,参考文献83篇。更多还原

【Abstract】 The Diyanqinamu Mo deposit is located in the Dongwuqi fold belt of the Dongwuqi-Zalantun volcanic passive continental margin accretion belt of the southeastern Siberian plate.It has experienced tectonic activities such as the closure of the Paleo-Asian Ocean,the subduction of the Paleo-Pacific plate,and the orogeny in Central Asia.The mineralization geological conditions are good,and it is one of the super-large molybdenum deposits discovered in recent years.This paper on the basis of detailed field geological survey and indoor study,through the zircon U-Pb dating science,rock geochemistry analysis test method,determination of diagenetic metallogenic epoch,the analysis of metallogenic tectonic background and cause,provide theoretical guidance for the mining of deep and periphery prospecting,at the same time serve as a reference for the domestic and foreign geological workers looking for similar ore deposits.The research progress and achievements of this paper are as follows:Ore body of Diyanqinamu Mo deposit occurs in the andesite and tuff of Chaganuoer Formation in Mesozoic Jurassic.In the horizontal plane is a ring,the four sides of the ore body is relatively straight,the intersection is an arc of the ring distribution;In the section,the ore body extends downward in a tubular form,and the ore body slopes inward slowly and steeply,and has a tendency to shrink toward the rock mass in the deep.The orebody is 2.5km from east to west and 2km from north to south,with an average grade of 0.097%and a molybdenum content of778 thousand tons.The molybdenum mineralization types are mainly lumpy,disseminated and reticulated.The alteration of surrounding rock is developed,including silicification,pyrite sericitization,bluvitization,mudization,etc.LA-ICP-MS zircon U-Pb isotopic measurements show that the weighted average ages of ²⁰⁶Pb/²³⁸Ufor monzogranite porphyry and alkaline-feldspar granite porphyry related to mineralization are 158±1.8Ma and 158±2.0Ma,respectively,which are basically consistent with the Re-Os ages of molybdenite samples in the orebody（157±2.8Ma）.It is slightly earlier than the metallogenic age of molybdenite,indicating that monzonite granite porphyry,alkalinite granite porphyry and molybdenite ore body formed in the same tectonic magmatic activity,and the diagenetic and metallogenic age in the study area was late Jurassic.Rock geochemical analysis results show that the long monzonitic granite porphyry and alkali granite porphyry have poor high silicon,potassium,magnesium,rich,poor calcium aluminum,for aluminum high in potassium calc-alkaline series rocks,light rare earth concentration,heavy rare earth losses,with strong europium negative anomaly,no ce anomaly,the enrichment of Rb,Th,U,Sm,K and other elements,The depleted Ba,Sr,P,Ti and other elements,with high Rb/Sr,Nb/Ta,Zr/Hf ratios,belongs to the peraluminous A-type granite,magma originated from the lower crustal source area.The initial temperature of ore-forming fluid in the deposit is characterized by high temperature,high salinity and high oxygen fugacity.The ore-forming material mainly comes from the deep acidic magmatic hydrothermal solution,which is a typical porphyry molybdenum deposit.The deposit is characterized by low Mo,less CO₂inclusions,high Na and High Cl,and belongs to Endako type porphyry molybdenum deposit.In the late Mesozoic,the thickened lithosphere disintegrated and subsided,the acidic magma rich in ore-forming materials and volatiles upwelled,and rapidly condensed and crystallized on the surface to form porphyry granite.The ore-forming hydrothermal solution in the deep part of the magma chamber rose along secondary faults and fissures,and contacted with the surrounding rocks.The ore-forming fluid experienced secondary boiling,and the molybdenum element was broken from equilibrium,Large scale precipitation took place and finally formed the diyanqinamu molybdenum deposit.There are 19 figures,9 tables and 83 references in this paper.更多还原