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青海祁漫塔格多金属成矿带典型矿床地质地球化学研究
【作者】 徐国端；
【导师】 韩润生；
【作者基本信息】 昆明理工大学 ， 矿产普查与勘探， 2010， 博士
【摘要】 青海祁漫塔格铁-铜-铅-锌-钨-锡-金-钴多金属成矿带是我国西部秦(岭)-祁(连)-昆(仑)一级成矿带(亦称中央成矿带)中的主要组成部分。该成矿带近年来在地质找矿方面取得了重要进展,资源潜力巨大。因此,该成矿带典型矿床地质地球化学及其成矿规律的系统研究具有重要的科学价值和现实意义。本文“青海祁漫塔格多金属成矿带典型矿床地质地球化学研究”紧密结合中国地质调查局青藏高原地质矿产调查与评价专项“祁漫塔格地区成矿条件研究与找矿靶区优选”(项目编码：1212010818091)项目选题,针对研究区地质研究程度低、矿床类型多、成矿作用复杂的现状,以祁漫塔格成矿带典型矿床为主要研究对象,通过矿床解剖和细致研究,应用岩石学和微量元素、同位素、流体包裹体地球化学及数理统计分析等综合研究方法,从广度和深度为找矿靶区优选和西部高寒荒漠地区找矿靶区快速评价技术组合探索提供了科学依据。论文取得以下的主要成果和认识：(1)厘定了该成矿带典型矿床的矿床类型,建立了构造-岩浆活动演化与矿床关系模式。在区域地质背景和矿床地质特征研究的基础上,系统地分析了典型矿床的控矿因素及其成因,认为该区是多矿床类型、多成矿系统复合叠加的多金属成矿带,具有优越的成矿地质条件与寻找喷流沉积型-岩浆热液叠加型铜钴多金属矿床、矽卡岩-斑岩型铁铜多金属矿床和造山带型金矿床的良好前景；肯德可克矿床属喷流沉积型-矽卡岩型叠加复合型铁钴多金属矿床,卡尔却卡矿床属岩浆热液型铜多金属矿床,四角羊沟矿床属矽卡岩型铅锌矿床,虎头崖矿床属矽卡岩型铜铅锌银矿床。结合构造-岩浆演化过程,建立了构造-岩浆活动演化与各类矿床关系模式。(2)系统总结了典型矿床地球化学特征。在矿床地质特征分析的基础上,从岩石学、岩石化学、稀土元素、微量元素、数理统计分析等方面总结了四个典型矿床地球化学特征。除肯德可克地区闪长岩(SiO2 62.30%)外,其它成矿岩体均为典型酸性钙碱性花岗岩(SiO2≥65%；里特曼指数σ：0.57-2.16)；稀土配分模式属铕亏损-轻稀土富集型(δEu：0.56-0.76),表现出S型花岗岩和造山型花岗岩的特征；稀土分配模式显示,除矿石∑REE明显偏低与岩体和围岩有明显分离外,与岩体和围岩分配模式相似,反映了其成矿作用与岩体、围岩有密切的亲缘关系,岩体为主要的成矿地质体；微量元素特征对比显示肯德可克、卡尔却卡矿床靠近岩体的矽卡岩内接触带有利于成矿元素富集,而虎头崖矿床的外接触带有利于成矿元素富集。(3)同位素示踪成矿物质具有多源性。通过典型矿床矿石铅同位素特征分析,发现矿石铅同位素组成以岩浆作用有关的幔源铅与壳源铅相混合的造山带铅为特征,认为成矿物质在成矿过程中受到多源混染的强烈影响,幔源物质可能参与了成矿作用,成矿过程伴随有强烈的火山活动；通过硫同位素特征研究,硫同位素组成较分散(-3.08‰-12.23‰)。其中卡尔却卡、四角羊沟矿床634S集中于4.37‰-6.39‰之间,反映了硫主要来源于成矿岩体。(4)典型矿床矿物流体包裹体特征反映成矿流体来源以岩浆水为主,矿床的形成是两种成矿流体发生混合作用的产物。矿物流体包裹体形态不规则,大小悬殊(4gm-46μm),均一温度、盐度范围大(89℃～344℃；0.71～42.4.wt％NaClequiv),流体密度范围较大(0.651 g/cm3-1.033g/cm3)。这一特征显示出成矿过程中存在两种成矿流体：高盐度-中高温度-高密度流体与中低温-低盐度-低密度流体,反映了成矿热液主要来源于岩浆水,并有加热的大气降水加入,显示出该类矿床成矿热液的共性特点。(5)提出该区处于柴达木盆地西南缘与东昆仑造山带之间的多期复合造山带成矿构造背景的新认识。在前人研究的基础上,认为祈漫塔格地区未出现有明显的俯冲带岛弧、深海沟和弧前弧后盆地等板块空间结构序列,在总体构造格架上为柴达木盆地西南缘与东昆仑造山带之间的多期复合造山带。(6)划分了5个成矿亚带,并提出其找矿前景。在研究该区构造演化的基础上,依据地质构造、岩浆活动、矿床类型的差异,编制了祁漫塔格地区(青海段)的(三级)矿化分区图,共圈出五个成矿亚带：①滩北雪峰加里东隆起区W-Sn-Au-Cu成矿亚带；②祁漫塔格前山加里东—印支叠加复合坳陷区Fe-Cu多金属成矿亚带；③祁漫塔格前山印支造山隆起区Cu-Mo多金属成矿亚带；④那棱格勒河坳陷区Fe多金属成矿亚带；⑤祁漫塔格后山加里东一印支叠加复合隆起区Cu-W-Sn多金属成矿亚带。在此基础上,探讨了各亚带的找矿类型与找矿前景。
【Abstract】 The Qimantage Fe-Cu-Pb-Zn-W-Sn-Au-Co polymetallic ore belt in Qinghai is the the major component of the first order Qing (Ling)-Qi (Lian)-Kun (lun) metallogenic belt (also known as central metallogenic belt) in western China. In recent years, the geological prospecting of this metallogenic belt has made significant progress, and resources shows great potential. Therefore, the systematic geological and geochemical research of this typical ore deposits has the important scientific value and practical significance.The topic selection of this thesis combines with the Bureau of Geology and Mineral Resources Survey and Evaluation of Qinghai-Tibet Plateau special project of China Geological Survey (project number:1212010818091). According to the low level of geological research in the study area, multi-type deposits and complex mineralization, aim at Qimantage typical deposit metallogenic belt as the main object, through careful study and the anatomy of deposits, applied petrological and trace elements, isotopes, geochemistry and fluid inclusion analysis, mathematical statistics, comprehensive research methods, from the breadth and depth of the ore-prospecting target selection and prospecting target areas in western alpine desert to explore the rapid assessment technology portfolio, the thesis provides the scientific basis. The thesis achieves the following main results:(1) The thesis determines deposit types and established the model of the relationship between magmatic evolution and deposit models. Based on the regional geological background and mineral geological characteristics, the ore-controlling factors and its genesis are systematic analyzed. It concludes that deposits are multi-metal ore belt of multi-deposit type and multi-composite superimposed metallogenic system, with superior the ore-forming geological conditions and prospects and looking for SEDEX-type overlay-type Cu-Co magmatic hydrothermal polymetallic deposits, skarn-Cu-porphyry iron deposits and orogenic-type gold deposits. Kendekeke deposit belongs to SEDEX-skarn overlay-type Fe-Co polymetallic ore deposit. Kaer belongs to the magmatic hydrothermal polymetallic ore deposit, Sijiaoyanggou belongs to skarn-type lead-zinc deposit. hutouya belongs to skarn-type copper-lead-zinc silver deposit. Combination of tectonic-magmatic evolution, the thesis established tectonic-magmatic activity evolution model and the relationship between various types of deposits.(2) The typical geochemical characteristics of deposits were systematically summarized. Based on the analysis of geological features, the petrology, petrochemistry, REE, trace elements, mathematical statistics and so on, sums up the four typical geochemical characteristics of deposits. Expect the Kendekeke area can be diorite (SiO2 62.30%), other rock forming calc-alkaline granites are typical of acid (SiO2≥65%; Rittmann indexσ:0.57～2.16); REE patterns are Eu loss-LREE enrichment type (δEu: 0.56～0.76), show S-type granites and orogenic-type granites; REE distribution patterns were similar with the rock and surrounding rock, except to the ore∑REE significantly lower with a clear separation. It reflects that the mineralization and rock, surrounding rock has a close genetic relationship. The rocks are the main ore-forming geological bodies. The comparison of trace element characteristics shows that Kedekeke, Caerque close to the skarn inner contact zone are favorable to enrichment of ore-forming elements, while the external contact zone of hutouya deposit are favorable to enrichment of ore-forming elements.(3) The thesis concludes that the isotope tracer has multi-sources. Through the typical characteristics of lead isotope in ore deposits, it can be concluded that the ore lead isotopes composed with the mantle-derived magmatism lead and crust-derived lead. The ore-forming materials are processed by the multi-source contamination, and the mantle-derived substances may be involved in mineralization. The mineralization are accompanied by strong volcanic activity. The sulfur isotopic characteristics are more decentralized (-3.08‰～12.23‰).δ34S of Kaerqienei and Sijiaoyanggou focused on the 4.37‰～6.39‰, reflecting the mineralization of sulfur comes mainly from rock.(4) the typical characteristics of fluid inclusions in mineral deposits reflects that the sources of ore-forming fluid are mainly magmatic water, mineral deposit formation are two ore-forming fluid mixing. The fluid inclusions are irregular shape, size disparity (4μm～46μm), homogenization temperature, salinity range (89℃～344℃; 0.71～42.4 wt% NaCl equiv), fluid density range (0.651 g/cm3～1.033g/cm3). This feature shows that there are two ore-forming process of ore-forming fluids:high salinity-high temperature high-density fluid and low temperature-salinity-low-density fluid, reflecting the ore-forming hydrothermal mainly from magmatic water, with the heated meteoric water. It shows the common feature of hydrothermal ore deposits.(5) The thesis proposes that the study areas located at the multi-phase composite orogenic tectonic between the southwestern edge of the Qaidam Basin and East Kunlun. Based on the previous studies, it is conclude that Qimantage areas do not appear significantly island arc subduction zones, deep trench and fore-arc-arc basin sequence, and the spatial structure is the multi-phase composite orogenic belt between the southwestern edge of the Qaidam Basin and the East Kunlun orogenic belt.(6) The thesis sub-divides the study area into five metallogenic belt, and proposes minimization prospecting. Based on the geological structure, magmatic activity and comparison of deposits types, prepared Qimantage region (Qinghai Section) (3) mineralization zoning map, and five ore deposit sub-band:①Tanbeixuefeng Caledonian uplift W-Sn-Au-Cu metallogenic ore belt;②Qimantage Maeyama Caledonian-Indo-overlay composite Depression Fe-Cu-polymetallic metallogenic ore belt;③Qimantage before the Indo-orogenic uplift Mountain Cu-Mo-polymetallic ore belt;④Nalenggele river depression Fe-polymetallic ore belt;⑤Qimantage Caledonian-Indo-Chinese superposition compound uplift Cu-W-Sn-polymetallic ore belt. On this basis, the thesis discusses the different of ore belt and the deposit prospection.