内蒙古浩尧尔忽洞金矿床地球化学特征及成因分析

发布时间：2018-12-28 18:41

【摘要】：浩尧尔忽洞金矿位于华北地台北缘西段,行政上隶属于内蒙古自治区巴彦淖尔市乌拉特中旗新忽热乡。该金矿为一大储量、低品位矿床,已经探明的金矿资源储量达148t,矿石平均品位约为0.82g/t。本次论文在收集整理前人成果的基础上,结合多次的野外地质调查和大量的室内研究工作,综合区域地质背景、矿床地质特征、岩浆岩主微量和稀土元素、矿石S、Pb同位素及黑云母40Ar/39Ar同位素年龄等方面的特征,对浩尧尔忽洞金矿的矿床地球化学特征和成因进行了探讨。该矿床矿体呈层状、似层状产出,并严格受构造破碎带及挤压片理化带控制,控矿岩性主要为比鲁特组第一、二岩段含碳质变细砂岩、板岩和千枚状板岩等。矿区范围内褶皱和断裂构造十分发育,并分布有大量海西期花岗质岩体和岩脉。根据矿区所采岩浆岩样品的主微量、稀土元素成分数据投图分析得出:浩尧尔忽洞金矿区岩浆岩的主要岩石类型有闪长岩、花岗岩、辉长岩、闪长玢岩、黑云母花岗岩等,各类岩石均属于高钾钙碱性系列;各类岩石均显示出大离子亲石元素相对富集、高场强元素相对亏损,轻稀土富集、轻重稀土分馏明显的特征。利用主微量、稀土元素数据进行构造环境投图分析认为,浩尧尔忽洞金矿区中酸性侵入岩主要形成于板块碰撞前-同碰撞构造环境下,与二叠纪晚期的华北板块和西伯利亚板块的碰撞运动密切相关,板块碰撞前-同碰撞时期岩体的侵入对浩尧尔忽洞金矿床的形成起到了关键的作用。矿区石英脉的黑云母40Ar/39Ar同位素坪年龄为(260.1±2.9)Ma,反等时线年龄为(260.9±3.4)Ma,该年龄可准确地间接指示浩尧尔忽洞金矿床的成矿年龄,属二叠纪晚期,与区域上大量海西期岩浆岩地质年龄事实相吻合,充分证明该矿床金成矿作用与海西期构造-岩浆活动密切相关。矿石中黄铁矿和磁黄铁矿的硫同位素结果表明,该矿床的硫具有相对均一的来源,主要来源于受碳酸盐污染的花岗岩岩浆。矿石铅同位素结果表明,浩尧尔忽洞金矿铅具有壳幔混合来源的特征,并受到后期海水沉积作用的改造。
[Abstract]:The Haoyao Erhuodong gold deposit is located in the western section of the North China Taipei margin, and administratively belongs to the Xinhuarge Township of Wulat Middle Banner, Bayannur City, Inner Mongolia Autonomous region. The gold deposit is a large reserve, low grade ore deposit, the proven reserves of gold resources up to 148 t, the average grade of ore is about 0.82g / t. On the basis of collecting and arranging the previous achievements, combining with many field geological surveys and a lot of indoor research work, this paper synthesizes the regional geological background, the geological characteristics of the deposits, the main trace and rare earth elements of magmatic rocks, the ore S, The geochemical characteristics and genesis of the Haoyaolhuodong gold deposit are discussed in terms of Pb isotopic and biotite 40Ar/39Ar isotopic ages. The ore body of the deposit is stratiform, similar to stratiform, and is strictly controlled by structural fracture zone and compressional sheet physical and chemical belt. The ore-controlling rocks are mainly carbon-bearing fine-grained sandstone, slate and thousand slate in the first and second member of the Bilutt formation. The fold and fault structures are well developed in the mining area, and a large number of Hercynian granitic rocks and veins are distributed. According to the principal trace and REE composition data of magmatic rock samples taken from the mining area, it is concluded that the main rock types of magmatic rocks in the Haoyaolhuodong gold deposit area are diorite, granite, gabbro, diorite porphyrite, biotite granite, etc. All kinds of rocks belong to high potassium calc-alkaline series; All kinds of rocks are characterized by the relative enrichment of large ion lithophile elements, the relative depletion of high field strength elements, the enrichment of light rare earth elements and the obvious fractionation of light rare earth elements. Based on the main trace and rare earth element data, it is found that the intermediate-acid intrusive rocks in the Haoyaodong gold deposit are mainly formed in the pre-collision and syncollision tectonic environments. It is closely related to the collision movement of the North China plate and the Siberian plate in the late Permian. The intrusion of the rock mass from the plate collision to the same collision period played a key role in the formation of the Haoyaolhuodong gold deposit. The 40Ar/39Ar isotopic plateau age of biotite in quartz vein is (260.1 卤2. 9) Ma, antiisochron age of (260.9 卤3. 4) Ma,. The age can indicate indirectly the metallogenic age of the Haoyaoerhudong gold deposit, which belongs to the late Permian period. In accordance with the geological age of a large number of Hercynian magmatic rocks in the region, it is fully proved that the gold mineralization of the deposit is closely related to the Hercynian tectonic-magmatic activity. The sulfur isotopic results of pyrite and pyrrhotite in the ore show that the sulfur of the deposit is relatively uniform, mainly from the granite magma contaminated by carbonate. The results of ore lead isotope show that lead in Haoyaolhuodong gold deposit is characterized by mixing of crust and mantle and has been modified by late seawater sedimentation.
【学位授予单位】：长安大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：P618.51

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