【作者】 赵江南；

【导师】 赵鹏大；

【作者基本信息】 中国地质大学 ， 矿产普查与勘探， 2012， 博士

【摘要】 羊拉大型铜矿床在区域上处于“三江”(金沙江、澜沧江、怒江)古特提斯构造域中段,隶属中咱陆块与昌都-思茅陆块相夹持的金沙江板块缝合带。研究区域羊拉铜矿区从北到南包括江边矿段、里农矿段及路农矿段,其中里农矿段和路农矿段为主采矿段。本文紧紧围绕羊拉矿区特别是里农矿段矿体为主要研究对象,在深入探讨与形成矿体产出相关的赋矿围岩、花岗岩类以及矽卡岩的地质地球化学特征基础之上,着重对里农矿段2号以及5号矿体展开从矿物学、岩石学、矿床学、地球化学等方面的系统研究,最后总结矿区成矿多样性及矿床谱系规律,建立羊拉矿床成矿模式,并对矿区做深部找矿预测评价,通过研究,所获主要成果及认识如下：(1)通过对羊拉矿区赋矿围岩的地球化学元素分析,矿区主要赋矿地层的金属元素Cu、Pb、Zn、Bi、Zn、W、Mo等元素富集,明显高于地壳均值,赋矿地层纹层状硅质岩的发育以及Ba元素在地层中较强富集,反映了地层形成中受到热水沉积作用,表明地层具有为矿体的形成提供了部分物质来源的条件；(2)在充分分析羊拉矿区主要岩体的矿物组成、主量元素以及微量元素基础上,探讨了对羊拉矿区岩体的岩浆来源、形成的地质背景,对岩体的含矿性进行了评价。羊拉花岗岩属钙碱性准铝质-弱过铝质Ⅰ型花岗岩。各岩体微量元素普遍富集Rb、Th、U、K和La等大离子亲石元素,相对亏损Nb、Ta、Zr及Hf等高场强元素,稀土元素分配模式均表现为较弱的铕负异常的右倾斜的平滑曲线,反映岩体之间具有相似的岩浆源区；综合区域、微量元素以及同位素资料,探讨了花岗岩类形成的地质背景,认为羊拉矿区花岗岩主要形成于金沙江洋盆向西昌都-兰坪陆块之下俯冲的岛弧环境,兼具火山弧型和同碰撞型之间的过渡型花岗岩体；岩浆活动对活化成矿物质及形成羊拉铜矿起到了重要作用,从岩体矿化形式、元素富集特征等方面对花岗岩体与成矿关系特征进行了评价；(3)在羊拉铜矿矽卡岩矿物学、地球化学以及矽卡岩成岩成矿过程方面的研究取得了一些新进展：厘定了羊拉主要矽卡岩矿物类型,主要包括辉石以及石榴子石,辉石以钙铁辉石以及透辉石为主,石榴子石主要包括钙铁榴石以及钙铝榴石；矽卡岩具有一定的空间分带,近岩体的矽卡岩中石榴石含量较高,远岩体的矽卡岩中透辉石含量较高；矿床石榴子石具有环带现象,体现了石榴子石在生长过程中物理化学、流体组成等环境的变化；探讨了Sn元素在石榴子石中的含量以及赋存特征,显示Sn在石榴子石具有较高含量,高含量的锡主要以Sn4+离子状态以类质同相形式存在于石榴子石中；对矽卡岩以及矽卡岩单矿物石榴子石、透辉石稀土元素以右偏Eu正异常的特征产生的原因进行了分析；通过典型剖面地球化学定量分析证明了矽卡岩形成过程中与岩体以及围岩之间发生了物质的迁入与迁出,进一步确认了矿区矽卡岩成矿作用类型为接触渗滤交代作用；(4)矿区典型矽卡岩型矿体2号以及5号矿体地质地球化学研究进展：对矿体的品位数值特征进行了定量分析,矿段品位表现为双峰以及多峰特征,分析了矿体品位的空间变化规律；厘定了矿体的形成阶段,包括接触变质期、石英硫化物期以及表生期,大规模矿化发生在石英硫化物期；构建了矿体垂向原生晕分带模式,垂向原生晕表现为上部As、Pb、 Zn,中部Ag、W、Bi、Mn,下部Cu、Sn、Mo的分带特征,体现了矿物形成的由中低温环境到中高温环境变化,构建了原生晕定量评价模型,选取分带指数值Pb*Zn*Ag*Bi/Cu*Sn*Mo作为构建深部找矿预测模型的指标；(5)系统分析了铅、硫、碳、氢、氧同位素组成,对矿体形成的物质来源与成矿环境提供了比较全面的证据：在铅模式图上,矿石铅主要落在上地壳与造山带演化曲线之间,也有少数样品落在上地幔与造山带之间,表明矿体中铅主要为地壳来源,但同时也包括地幔组分的加入,本区的主要长石铅以及矿石铅均落在岛弧的范围内,表明在本区在古特提斯成矿作用过程中本区处于岛弧的环境；矿区主要硫化物硫同位素接近0,均一化程度较高,频率直方图上表现明显的塔式分布规律,表明矿床各个溶液硫具有相当均一的性质,硫源比较单一,显示地壳深部硫的来源特征,主要属于幔源硫,硫同位素变化范围小,显示矿床与岩浆具有密切成因联系；氢氧同位素数据表明矽卡岩矿床矿液来源除岩浆水外,大气降水的作用在羊拉矿区成矿的后期比较显著；碳氧同位素结果表明矿石中方解石脉、岩体接触带附近方解石脉以及大理岩型矿石的方解石中的碳、氧可能同时受到了里农岩体的侵位与改造；(6)分析了矿区的成矿多样性特征,构建了成矿多样性规律性序列,建立矿区时间-空间-成因谱系,并基于成矿多样性以及矿床谱系特征,提出了综合找矿以及综合利用的意见与建议；对金沙江构造带主要类型铜矿进行了对比研究,总结了羊拉矿床控矿因素、找矿标志以及成矿模式,对矿区找矿远景区进行了圈定与评估,提出了预测依据以及主要方法,确定里农路农结合部、里农矿段深部地区、路农采场北部深部地区具有深部找矿远景,有待更进一步的勘查与研究工作。更多还原

【Abstract】 The large copper deposit, Yangla deposit, which belongs to Jinsha River plate suture zone gripped by Zhongza landmass and Changdu-Simao landmass, lies in the middle piece of the three-rivers(Jinsha River, Lancang River and Nu River) Paleo Tethys tectonic zone. The Yangla copper orefield discussed by this article contains the Jiangbian ore block, the Linong ore block and the Lunong ore block from north to south, the Linong and Lunong ore blocks are the main mining section. Based on the thorough discussion on the geochemistry characteristics of the ore-related surrounding rocks, granite and skarn, this article takes the Yangla orefield, especially the typical skarn type ore body in the Linong ore block, as main object of study, mainly discusses the mineralogical, petrological and geochemical characteristics of the Ⅱ#and Ⅴ#ore body in the Linong ore block. Finally, the author summarizes the metallogenic diversity and the metallogenic model of the deposit, and makes a deep prospecting prediction evaluation. The main results obtained as follows:(1)Based on the element content analysis, the wall rocks are found to be rich in Cu、Pb、 Zn、Bi、Zn、W、Mo, etc. Laminated siliceous rocks development and Ba enrichment in country rocks might represent that the stratum have experienced Hot water deposition, and the surrounding rocks might have provided some ore-forming materials.(2)Based on the mineralogy, major elements and trace elements analyses of the main granites in the Yangla orefield, the magma sources, the geological background and ore-bearing ability of the granites are discussed:the Yangla granite belongs to the calc-alkaline slightly peraluminous I type granite. The granites are commonly rich in large-ion lithophile elements such as Rb、Th、U、K and La, but in depletion of HFS elements such as Nb、Ta、Zr and Hf. The REE distribution patterns are characterized by LREE enrichment and slightly negative Eu anomalies, which represent that the granites have the same magma source. The granites in the Yangla orefield mainly formed in island arc environment which formed because of the subduction of the Jinsha River ocean basin under the Xichangdu-Lanping landmass. The granites have both volcanic arc type and S-COLG type. The magmatism plays a significant role in the activation of ore-forming materials and the formation of the Yangla deposit.(3)Some new progress has been made in the mineralogy and geochemistry of the skarn and its role in the ore-forming process. The skarn mainly consists of pyroxene and garnet. The pyroxene are mainly hedenbergite and malacolite, while the garnets are mainly andradite and essonite. The skarn has some kind of zoning in space. The rock near terrace contains more garnet, while others far away from the terrace contain more malacolite. Bands, which reflect changes in the physical chemical conditions and fluid composition, can be seen in the garnet of the deposit. The garnet has a high content of the element Sn, which occurs in the form of isomorphism as Sn4+. This article also discusses the REE distribution pattern of the skarn minerals and the reason why Eu content is abnormal. It has been proved by the geochemical analyzes of the typical section that there was material interchange between the granites and wall rocks during the skarn formation. The mineralization has been proved to be dimetasomatism.(4) Geological and geochemical study progress has been made for the Ⅱ#and Ⅴ#ore body. Quantitative analysis of mineralization grade and its space variation has been made. The mineralization grade has a character of two-peak type or multi-peak type. The mineralization has been divided into three phases, the quartz sulfide phase is the main metallogenic phase. The vertical primary halo pattern of the ore body has been made:As、Pb、Zn enrichment mainly occurs in upper part of the ore body, while Ag、W、Bi、Mn in the central section and Sn、Cu、 Mo in the bottom, which represents the changes in the mineral formation from mesotherm-microthermal to highheat environment. The the quantitative evaluation model has been built, chosing the zoing index as the Pb*Zn*Ag*Bi/Cu*Sn*Mo as the indicator of the model.(5) Evidence of the source of ore-forming materials have been put forward by analysing the Pb, S, C, H, O isotope. The Pb isotope of the ore mainly lies between the evolution line of the upper crust and orogenic belt, while minority samples lies between the evolution line of the upper mantle and orogenic belt, which indicates that the Pb of the deposit mainly came from crust, but also with some mantle materials. Most of the Pb isotope of feldspar and ores lie in the district of island arc, which implies that this area is island arc while the mineralization took place. The S isotope data are concentrated close to0, which occurs as a tower distribution. It suggests that the ore-forming fluid had a single S source. The S of the deposit may came from mantle and has an intimate relationship with granites in this district. The H-O isotope suggests both magmatic water and atmospheric water are involved in the ore-forming fluid, and atmospheric water mainly occured during the late phase of the mineralization. The C-O isotope implies that the C and O element in the calcite vein, around the terrace, or the marble type ore may have relation with both the marble and the influence of the Linong rock mass.(6) The metallogenic diversity has been discussed, the regularity sequence and the time-space-genesis pedigree has been built. This article also compares the main copper deposit types in the Jinsha River tectonic zone, and summarizes the ore-controlling factors, the prospecting indicators, and metallogenic model of the Yangla deposit. Finally, the author put forward the ore-hunting prospect areas in this district by different evidences and specific method. The author pointed out that combining site of the Linong and Lunong district, the deep part of the Linong district and the north of the Lunong district may have great ore prospecting potential.更多还原