柴北缘地区的两类块状硫化物矿床——Ⅱ.青龙滩式VHMS型Cu-S矿床

文章综述了柴北缘地区的VHMS型Cu_S矿床———青龙滩式矿床,指出其容矿岩石为加里东造山带中被改造过的岛弧火山岩,该矿床中含铜硫化物矿层形成后不但遭受过构造的强烈改造,而且也受后期矽卡岩化的改造和叠加。放射性同位素测年结果表明,青龙滩矿床的主岩———安山岩形成于晚寒武世(514.2±8.5)Ma,后期的矽卡岩矿化大约发生在290Ma。柴北缘加里东造山带中既产有VHMS型Cu_S矿床(如青龙滩矿床),也产有SEDEX型Pb_Zn矿床(如锡铁山矿床),两者的成矿地质构造背景和形成年龄不相同。柴北缘地区的早古生代洋(海)盆于晚寒武世俯冲消减,出现岛弧,并形成青龙滩等VHMS型Cu_S矿床,之后(早奥陶世),发生弧后拉张,形成弧后盆地及锡铁山等SEDEX型铅锌矿床。

新疆阿尔泰阿舍勒VHMS型铜锌矿床成矿流体的氦——氩同位素示踪

阿舍勒大型铜锌矿是我国典型的海相火山岩块状硫化物（VHMS）型矿床，赋存于阿舍勒盆地早一中泥盆世阿舍勒组海相火山一沉积岩系中。1号主矿体呈似层状或大透镜体状，矿石呈块状、浸染状、条带状、层纹状、细脉状。本文对块状、浸染状、条带状矿石的黄铁矿中流体包裹体He和Ar同位素进行了研究。黄铁矿中流体包裹体的。He含量为（64．5～173．0）×10-7cm-3STP／g，n（3He）／n（4He）值为（0．1358～0．379）Ra，幔源He的含量为1．79％～5．55％，表明成矿流体中He主要来源于地壳。40Ar含量为（0．318～4．69）×10-7cm3STP／g，n（40Ar）／n（36Ar）值变化于389．1～9425，40Ar＊含量为24．06％-96．89％，表明成矿流体中存在含有放射性成因Ar的海水加入。结合矿床的氢、氧、硫同位素特征，认为成矿流体来源为海水和幔源岩浆热液。

四川呷村VHMS矿床:从野外观察到成矿模型

呷村矿床是一个与晚三叠世海相钙碱性酸性火山岩系有关的典型块状硫化物（ＶＨＭＳ）矿床。热水流体系统和贱金属成矿作用发育于义敦岛弧碰撞造山带上的弧间裂谷盆地内，并受其内部的一系列局限盆地及ＳＮ向基底断裂－裂隙系统控制。含矿岩系为双峰岩石组合，具火山碎屑岩－矿体－喷气岩“三位一体”特征。硫化物矿床具有“块状矿席＋层控网脉状矿带”式三维结构特征。块状矿席发育多旋回的硫化物－硫酸盐韵律型式，揭示热水流体在海底的幕式排泄以及硫化物－硫酸盐在卤水池内的韵律式化学淀积和滑塌堆积过程。层控网脉状矿带产出于流纹质火山岩系，与上覆的块状矿席平行展布，揭示高渗透性碎屑岩层和多条同级别断层或断裂共同约束海底下部热水流体，并诱导其“弥散式”排泄和侧向流动交代。热水流体的传导冷凝过程导致硫化物沉积，热水流体与冷海水的简单混合导致硅质岩或／和重晶石淀积，传导冷凝与海水混合的联合作用导致含硫化物重晶石、硅质岩和红碧玉形成。

四川呷村VHMS矿床:从矿石化学分析到地球化学模型

中国四川呷村矿床是一个典型的含金富银多金属 ＶＨＭＳ矿床，其主要成矿金属元素 Ｃｕ，Ｚｎ，Ｐｈ，Ａｇ，Ａｕ丰度型式均呈非正态分布，多由两重或多重母体构成，揭示矿床经历了两次以上的成矿作用过程。成矿金属元素总体上集中于块状矿带，但贱金属 Ｃｕ，Ｚｎ， Ｐｈ没有明显的下部富 Ｃｕ＋ Ｚｎ、上部富 Ｐｈ＋ Ｚｎ的分带，贵金属 Ａｇ、 Ａｎ没有显示明显的层位优选性。矿床构造恢复和化学结构图像显示，金属元素的空间分布和富集机制严格受海底凹陷盆地的基底张性断裂和热水喷口位置控制。至少有４条近ＳＮ走向的盆地基底断裂带构成海底下部热水流体的迁移－排泄通道和网脉状矿带的容矿空间；近ＥＷ向断裂与４条ＳＮ向断裂的交汇部位，成为向上排泄的热水流体在海底的主要喷口，控制了金属元素在海底回地的空间分布。分别处于凹陷盆地东缘和西缘的热水喷口，因正地形地貌形态而形成山丘堆式矿体（ｍｏｕｎｄ－ｓｔｙlｅ），而处于凹陷盆地中心的热水喷口则积聚大量热水流体，构成卤水池，淀积席状块状矿体（ｓｈｅｅｔ－ｓｔｙlｅ）。

SEDEX型和VHMS型矿床及其成矿地球动力学背景的对比

尽管SEDEX型和VHMS型矿床都是成矿热液在海底喷出形成的矿床,但二者的成矿大地构造背景、成矿盆地类型、成矿金属和成矿流体的来源、成矿金属元素共生组合、控矿地质因素、成矿地球化学和物理化学条件、以及成矿地质时代和矿床空间分布等方面都存在很大的差异。

北秦岭铜峪VHMS型铜矿床赋矿火山岩地球化学、锆石U-Pb年龄及其地质意义

铜峪铜矿床是迄今在北秦岭西部认定的少数具有工业价值的VHMS型铜矿床,但该矿床研究程度较低(戴文晗,1982;宁晰春,1984;Lee et al.,2010;朱赖民等,2010)。铜峪铜矿床位于秦岭造山带北秦岭构造带中段斜峪关群中,在大地构造位置上处于商丹缝合带北侧,秦岭与祁连造山带的交汇部位。矿区地层总体走向北西西,东西两端分别被太白花岗岩体、宝鸡花岗岩体所截,中部煤沟花岗闪长岩体侵入于矿区背斜南翼。

中国两种VHMS型银矿床的基本特征

中国存在两种类型的ＶＨＭＳ型银矿床．其一为裂谷ＶＨＭＳ型银矿床，产于大陆裂谷构造环境中，受碱性橄榄玄武岩系列火山活动控制．银、铜为主要成矿元素；其二为岛弧ＶＨＭＳ型银矿床，产于岛弧带之上，其成矿作用与岛弧钙碱性系列火山活动关系密切．两种银矿床分别就位于粗安岩和流纹岩之中，它们的主成矿作用均发生于整个火山活动的晚期阶段．

陆相火山—斑岩Au、Ag、Pb、Zn、Cu矿床系统与VHMS矿床系统对比研究

陆相火山—斑岩型Ａｕ、Ａｇ、Ｐｂ、Ｚｎ、Ｃｕ、Ｍｏ矿床与海相火山岩块状硫化物型矿床，这两类极为重要的成矿系统，似乎属于两类完全不同的成矿体系。前者产于造山后挤压陆壳环境，与侵入作用关系密切，形成时代新、品位较低、规模大，易遭剥蚀；后者产于拉张洋壳和过渡壳环境，与火山喷发作用关系更密切，形成时代跨度大（太古代～至今），品位较高，且易遭受变质改造。然而相似之处亦很明显并具有某些内在联系，如均具双层矿床结构，火山—侵入建造组合具可比性，定位空间均以岩浆热源为中心，均存在中间岩浆房，矿化均与以绢英岩化为代表的热液蚀变相伴，成岩、成矿温度相近，成矿系列矿床组合相似。某些地区由于所处构造环境的变化，早期形成ＶＨＭＳ矿化，晚期形成斑岩铜矿化系列，后者继承了前者的成矿物质。但陆相系列岩石（富Ｋ、Ｍｏ、Ａｇ）分异程度要高一些。关于这两类矿床的关系，长期以来存在诸多混乱认识。在对两类成矿体系进行系统对比的基础上，本文提出前述相似性暗示洋底与陆壳背景下火山岩浆活动具有统一的岩浆起源和成矿作用。二者之间的差别系由岩浆侵位浅表环境、地壳厚度、流体介质不同、造山作用的时空演化所造成。分析了该项研究所涉及的关键技术问题。最后指出了该项对?

东昆仑—柴北缘地区VHMS型矿床多元信息定位预测

运用基于GIS的多元信息成矿预测系统MRAS软件对东昆仑—柴北缘地区的VHMS型矿床进行定位预测,共圈出13个找矿靶区。东昆仑南带VHMS型矿床最具找矿潜力,构成了一条受地质与物、化探综合异常控制下的近东西向展布的铜钴金矿化远景区带,其中的万保沟、督冷沟、雪山峰、驼路沟及诺木洪河上游地区是重要的找矿靶区。

北秦岭铜峪VHMS型铜矿床地质特征及硫-铅同位素地球化学

铜峪铜矿床是迄今在北秦岭西部认定的少数具有工业价值的VHMS型铜矿床,但该矿床研究程度较低(戴文晗,1982;宁晰春,1984;Lee et al.,2010;朱赖民等,2010)。铜峪铜矿床位于秦岭造山带北秦岭构造带中段斜峪关群中,在大地构造位置上处于商丹缝合带北侧,秦岭与祁连造山带的交汇部位。

Zircon U-Pb Geochronology and Geochemical Characteristics of the Volcanic Host Rocks from the Tongyu VHMS Copper Deposit in the Western North Qinling Orogen and Their Geological Significance

Precise in situ zircon U-Pb dating and Lu-Hf isotopic measurement using an LA-ICP-MS system, whole-rock major and trace element geochemistry and Sr-Nd isotope geochemistry were conducted on the volcanic host rocks of the Tongyu copper deposit on the basis of further understanding of its geological characteristics. Three zircon samples from the volcanic host rocks yielded 206Pb/238 U weighted average ages ranging from 436±4 Ma to 440±5 Ma, which are statistically indistinguishable and coeval with the ca. 440 Ma northward subduction event of the Paleo-Qinling oceanic slab. The volcanic host rocks were products of magmatic differentiation that evolved from basalt to andesite to dacite to rhyolite, forming an integrated tholeiitic island arc volcanic rock suite. The primitive mantle-normalized trace element patterns for most samples show characteristics of island arc volcanic rocks, such as relative enrichment of LILE（e.g. Th, U, Pb and La） and depletion of HFSE（e.g. Nb, Ta, Ti, Zr and Hf）. Discrimination diagrams of Ta/Yb vs Th/Yb, Ta vs Th, Yb vs Th/Ta, Ta/Hf vs Th/Hf, Hf/3 vs Th vs Nb/16, La vs La/Nb and Nb vs Nb/Th all suggest that both the volcanic host rocks from the Tongyu copper deposit and the volcanic rocks from the regional Xieyuguan Group were formed in an island arc environment related to subduction of an oceanic slab. Values of ISr（0.703457 to 0.708218） and εNd（t）（-2 to 5.8） indicate that the source materials of volcanic rocks from the Tongyu copper deposit and the Xieyuguan Group originated from the metasomatised mantle wedge with possible crustal material assimilation. Most of the volcanic rock samples show good agreement with the values of typical island arc volcanic rocks in the ISr-εNd（t） diagram. The involvement of crustal-derived material in the magma of the volcanic rocks from the Tongyu copper deposit was also reflected in the zircon εHf（t） values, which range from-3.08 to 10.7, and the existence of inherited ancient xenocrystic zircon cores（2616±39 Ma and 1297±22 Ma）. The mineralization of the Tongyu copper deposit shows syn-volcanic characteristics such as layered orebodies interbedded with the volcanic rock strata, thus, the zircon U-Pb age of the volcanic host rocks can approximately represent the mineralization age of the Tongyu copper deposit. Both the Meigou pluton and the volcanic host rocks were formed during the ca. 440 Ma northward subduction of the Paleo-Qinling Ocean when high oxygen fugacity aqueous hydrothermal fluid released by dehydration of the slab and the overlying sediments fluxed into the mantle wedge, triggered partial melting of the mantle wedge, and activated and extracted Cu and other ore-forming elements. The magma and ore-bearing fluid upwelled and erupted, and consequently formed the island arc volcanic rock suite and the Tongyu VHMS-type copper deposit.

VHMS系统和接口模块在830E-1AC卡车上的应用

小松830E-1AC型电传动卡车作为具有代表性的交流卡车,安装有一套VHMS系统及与其配合进行故障检测、诊断的接口模块。文章主要通过日常积累的经验对其VHMS系统和接口模块的特性及使用方法进行总结,从而对日后设备的维修提供借鉴。

北秦岭西部陕西铜峪VHMS型铜矿床矿化地质特征、成矿背景与矿床成因

本文对位于北秦岭西部斜峪关群中的陕西铜峪铜矿床矿化地质特征和矿石、矿化岩、赋矿火山岩围岩的主量、微量元素地球化学特征进行了详细研究,并对侵入于矿区南部的煤沟花岗闪长岩进行了单颗粒锆石LA-ICP-MSU-Pb精确定年、Lu-Hf同位素分析及岩石地球化学研究.研究表明,赋矿火山岩围岩为钙碱性岛弧火山岩,成矿物质与火山岩围岩具有相同的物质来源.铜峪铜矿床是古秦岭洋板片在472Ma左右的俯冲事件中,由俯冲板片脱水产生的高氧逸度流体进入地幔楔,活化萃取地幔楔的Cu等金属元素并导致地幔楔部分熔融产生的钙碱性岩浆在岛弧区喷发形成的VHMS型矿床.煤沟花岗闪长岩锆石U-Pb加权平均年龄为(439.3±3)Ma,显示其形成与古秦岭洋板片在440Ma左右的俯冲事件有关,岩石具有高Mg#,富Ni和Cr,轻重稀土强烈分馏,Eu异常不明显,高Sr、低Y、高Sr/Y比值,锆石Hf二阶段模式年龄集中在908～723Ma之间,εHf(t)>0,表明煤沟花岗闪长岩体属于俯冲的古秦岭洋玄武质板片部分熔融产生的熔体与地幔楔发生交代作用形成的具埃达克岩性质的岛弧花岗岩.铜峪铜矿床属形成于奥陶-志留纪之交((439.3±3)～(472±11)Ma))岛弧环境中的VHMS型块状硫化物矿床,与火山岩同期的火山喷流-沉积作用形成了该矿床的初始矿化;初始矿体形成后,伴随秦岭造山带印支期全面碰撞造山过程,矿体和含矿层受到强烈的构造改造和叠加.铜峪铜矿床与经典的VHMS型如日本黑矿型块状硫化物矿床存在差异,其矿化地质特征显示出岛弧火山喷发沉积和构造叠加改造成矿的双重特点.因此,铜峪铜矿床应为岛弧火山喷发沉积-构造叠加改造型矿床。

Geological characteristics,metallogenic background,and genesis of the Tongyu VHMS copper deposit in the west part of the North Qinling,Shaanxi Province

The Tongyu volcanic-hosted massive sulfide(VHMS) copper deposit is located in the west part of the North Qinling(NQL),Shaanxi Province.Here we report geological features and trace elemental characteristics of ores,mineralized rocks,and volcanic host rocks of this deposit.We also conducted in situ zircon U-Pb and Lu-Hf LA-ICP-MS dating and lithogeochemical study of the Meigou granodiorite,which is intruded in the south of the Tongyu mining district.It is inferred that the volcanic host rocks of the Tongyu Cu deposit belong to calc-alkaline island arc volcanic rocks,and the volcanic host rocks and the ore-forming materials share common material sources.During subduction of the Paleo-Qinling oceanic slab at around 472 Ma,high oxygen-fugacity aqueous fluid released by dehydration reaction of the subducting slab rose into the mantle wedge,leached Cu and other metal elements,and triggered partial melting of the mantle wedge.Associated with the ore-forming materials,the arc calc-alkaline magmas erupted and formed the Tongyu VHMS deposit.The weighted average zircon U-Pb age of the Meigou granodiorite is 439.3±3 Ma,suggesting its genesis is associated with the subduction event of the Paleo-Qinling oceanic plate around 440 Ma.In terms of the granitoid's geochemical characteristics,the Mg#,Ni,and Cr contents are high.REE show strongly fractionated patterns with unobvious Eu anomalies.Sr contents are high while Y contents are low,resulting in high Sr/Y ratios.Two-stage zircon Hf model ages mostly range between 908 and 723 Ma,with εHf(t)>0.Therefore,we classify Meigou granodiorite as island arc granite with adakitic geochemical features.It was generated by interaction between mantle wedge and melt produced by partial melting of the subducted basaltic slab of the Paleo-Qinling Ocean.The Tongyu VHMS deposit was formed in the island arc tectonic setting during Ordovician-Silurian between 439.3±3 Ma and 472±11 Ma.The volcanic exhalation-sedimentation,which was contemporaneous with the submarine volcanics,produced the primary mineralization of the Tongyu Cu deposit.Afterward,the ore bodies and host rocks were reworked and overprinted intensively by structures corresponding with the overall collisional orogenic process of the Qinling Orogenic Belt during the Indosinian period.In contrast to classic VHMS deposits such as the Kuroko deposit in Japan,the Tongyu Cu deposit possesses the dual characteristics of island arc volcanic exhalation and sedimentation as well as structural reworking and overprinting.Therefore,the Tongyu VHMS Cu deposit is a volcanic exhalation and sedimentation-structural reworking and overprinting type deposit.

^(40)Ar/^(39)Ar ages and stable isotopes of supergene jarosite from the Baiyin VHMS ore field, NE Tibetan Plateau with paleoclimatic implications

Supergene jarosite is widely distributed in weathering profiles derived from hypogene sulfide ores.Precise40Ar/39Ar dating and determination of hydrogen and oxygen isotopes of supergene jarosite can not only place tight constraints on the timing and history of continental weathering and supergene enrichment of sulfide ore deposits,but also shed significant insights into paleoclimatic conditions and tectonic uplift responsible for the weathering.In this paper,we present a preliminary study of40Ar/39Ar geochronology and stable isotope geochemistry of supergene jarosite from the early Paleozoic Zheyaoshan volcanic-hosted massive sulfide deposit of the Baiyin ore field located in the eastern portion of the Qilian Mountain along the northeastern(NE)margin of the Tibetan Plateau in an attempt to better understand the climatic conditions prevailed during the pervasive weathering in the region.Jarosite from the Zheyaoshan mining area occurs either as gravels within alluvial deposits over low-relief flat-top hills or cm-wide veins crosscutting weathered sulfide ores or their wall rocks.The gravels consist of massive jarosite aggregates with tabular crystal morphology and contain 8.21 wt%–8.31 wt%K2O on average.Two jarosite grains extracted from the gravels(08-02-2 and 08-02-5)yield well-defined40Ar/39Ar plateauages of 37.1±0.3 and 41.2±0.4 Ma(2r),respectively.They have dD values of-133%and-156%,and d18OSO4values of 2.6%and 2.5%.The vein-type jarosite consists of hexagonal pyramid crystals and contains much lower K2O,averaging at 2.44 wt%–2.72 wt%.Two jarosite veins(06-16-3 and 06-16-4)yield similar plateau ages of 3.2±0.1 and 3.3±0.1 Ma(2r),respectively.These jarosite veins have dD values of-158%and-160%,and d18OSO4values of 2.8%and 2.5%.The40Ar/39Ar ages indicate that sulfide ores of the Zheyaoshan deposit must have been brought to the surface since the late Eocene,and subsequently subjected to prolonged oxidation and supergene enrichment.The precipitation and preservation of jarosite in weathering profiles indicate that arid–semiarid climatic conditions must have been prevailed since the late Eocene.The hydrogen and oxygen isotopes of the jarosite further point to variation of climatic conditions in the area,with the Pliocene being slightly cooler relative to the late Eocene.Given that weathering profiles overlying sulfide ore deposits are widely distributed along the Qilian Mountain,systematic studies of40Ar/39Ar geochronology and stable isotope geochemistry of jarosite-group minerals from these profiles would provide valuable information on the timing and evolution of regional tectonic uplift,paleoclimatic changes,and supergene mineralization in this mountainous belt along the NE edge of the Tibetan Plateau.

海上风电吸力桩基础破坏包络面理论研究

在竖向荷载、水平荷载与弯矩荷载(VHM)共同作用的复合加载模式下,吸力桩基础地基达到整体破坏时各个荷载分量的组合在三维荷载空间中将形成1个不依赖于加载路径的椭圆曲面为破坏包络面。该文通过求解VHM三维荷载空间内的破坏包络面方程,分析海上风机机组吸力桩基础承载能力并确定吸力桩基础的失稳破坏模式,若设计基础承载力在屈服包络面之内,则认为基础的承载力和整体稳定性满足设计要求,并初步确定吸力桩基础的尺寸,为初步设计阶段提供方案设计指导性意见。在方案设计阶段,使用VHM三维荷载空间内的破坏包络面理论方法判断吸力桩承载力和稳定性是否符合要求,避免了繁琐的有限元计算,具有简化输入参数、无需划分网格和计算速率快等特点,研究成果可供工程设计参考。

哈萨克斯坦阿尔泰巨型成矿带的地质特征和成矿模型

概要介绍了哈萨克斯坦阿尔泰巨型成矿带的构造背景、地质特征、成矿规律、典型矿床特征及成矿模型。矿山阿尔泰是世界上著名的海相火山岩型块状硫化物（VHMS）铜-铅-锌多金属矿富集区，已发现十几个大型和超大型矿床。VHMS型矿床形成于泥盆纪裂谷发育阶段，赋存于玄武岩-流纹岩双峰式火山岩和陆源碎屑沉积岩中。与成矿有关的火山岩主要为中泥盆世吉维特期（380～370Ma），部分为早泥盆世和晚泥盆世。泥盆纪之后的大陆边缘俯冲、碰撞、岩浆热液活动，对裂谷阶段形成的VHMS型矿床进行不同程度的叠加改造。在早二叠世形成了与花岗岩有关的钨、锡，铌、钽、锂等稀有金属矿化。

云南大红山层状铜矿床成矿流体研究

云南大红山层状铜矿是大红山铁铜矿床的一部分。其成矿主要分为两个阶段:早期火山喷流作用形成了层状铜矿矿胚,而后期热液对原先的矿胚进行了改造和富集。本文选取大红山层状铜矿中石英脉型铜矿石石英样品系统地进行了流体包裹体的研究,主要发现了富液相(L+V)、含子晶多相(L+S±V)和纯 CO_2三类主要包裹体。显微测温结果表明,其均一温度在103～456℃之间;盐度范围为0.53%～59.76%NaCl equiv.,密度为0.80～1.45g/cm^3;纯 CO_2包裹体均一温度为-34.3～20.8℃,对应密度为0.77～1.09g/cm^3。稳定同位素测定结果表明,硫化物δ^(34)S 分布范围为-0.6‰～+10.9‰,表明岩浆硫和海水硫酸盐还原成因硫参与了早期成矿过程。方解石δ^(13)C_(PDB)值范围为-5.6‰～-3.1‰,与地幔碳同位素值(-5.0±2‰)完全吻合,暗示了热液中碳质有地幔来源。根据氧同位素方解石-水及石英-水之间的分馏方程,计算得到成矿流体中水的δ^(18)O_(SMOW)值在-1.9‰～13.7‰之间,与火成岩δ^(18)O 范围(5‰～15‰)基本一致。根据矿体地质特征、岩相学、流体包裹体以及稳定同位素等方面的综合研究,本文认为在喷流沉积之后的挤压环境下,从地幔分异出来的高温、中-高盐度并富含 CO_2的流体和海水一起改造了原岩,形成了变质火山—沉积岩,并使原先的铜矿矿胚活化富集。

三江北段治多-玉树地区火山成因铜多金属矿床地质特征及成矿构造环境

三江成矿带北段治多-玉树地区已显示出较大的铜多金属矿成矿潜力。在已有研究成果的基础上,结合详细的野外调查和室内研究,对三江北段治多-玉树地区新发现的典型铜多金属矿床的地质特征、成因类型和成矿构造环境进行了综述。这些矿床普遍赋存于中酸性火山岩中,空间上具"火山碎屑岩-矿体-热水沉积岩"的分布特征。矿体多为层状、似层状,且矿石品位较高。对比研究表明,治多-玉树地区铜多金属矿床地质特征与四川呷村矿床和日本"黑矿"矿床相似,成矿流体可能系岩浆水和海水的混合流体;成矿物质可能源于岛弧岩浆作用,并含有热液交代围岩所萃取的金属元素。研究结果表明该区以火山岩为赋矿围岩的铜多金属矿床应归属为VHMS型,成矿构造环境可能与晚三叠世甘孜-理塘洋向南俯冲的大洋岛弧-大陆边缘岛弧环境有关。

内蒙古别鲁乌图铜多金属矿床锆石U-Pb年龄和S、Pb同位素特征及其地质意义

为了明确内蒙古别鲁乌图铜多金属矿床的成矿年龄与矿床成因,对该矿床中与成矿关系密切的流纹岩进行了锆石U-Pb年龄以及主要金属硫化物的S、Pb同位素测试。其中流纹岩的锆石206Pb/238U加权平均年龄为(271.7±1.6)Ma(MSWD=1.02),显示成矿作用发生于二叠纪。金属硫化物的S同位素分析结果显示δ34SV-CDT值分布在-0.6‰~1.0‰之间,平均为0.49‰,变化范围较窄,显示S的来源单一;Pb同位素组成比较集中,206Pb/204Pb为18.207~18.674,207Pb/204Pb为15.620~15.699,208Pb/204Pb为38.144~38.790,具有壳幔混源的特征。S、Pb同位素特征均指示成矿物质主要来源于岩浆热液。结合区域地质、矿床地质、空间分带等特征以及S、Pb同位素组成可知,别鲁乌图铜多金属矿床为VHMS型矿床,形成于二叠纪陆缘弧裂谷中。