柴北缘双口山金- 银- 铅矿床赋矿围岩及含金石英脉热液锆石U- Pb定年对成矿时代的限定及其成因启示

双口山金- 银- 铅矿床地处柴北缘西段,赋存在滩间山变基性- 超基性变火山岩中。矿体由金矿体和银铅矿体组成,成矿作用与热液活动密切相关。本文通过对双口山含金矿体赋矿围岩及含金石英脉进行LA- ICP- MS锆石U- Pb年代学分析和研究。结果表明,赋矿围岩形成时代为443±2. 9Ma,与区域滩间山群火山岩形成年代一致(440~490Ma)。含金石英脉热液锆石U- Pb年代为402. 8±4. 2Ma,与区域金矿床成矿年龄以及韧性剪切带年龄相接近(~400Ma),代表了金矿体热液作用及成矿时代。结合地质特征及前人研究,表明双口山金银铅矿床是柴北缘造山带在不同造山带演化阶段,由不同成矿作用,在不同时期,相互叠加形成的复合型多金属矿床。金矿体具有典型造山型金矿床特征的变质热液型金矿,其成因主要与造山运动过程中的变质和变形作用有关, 成矿物质和流体来源于绿片岩相的滩间山群变基性- 超基性变火山岩。银铅矿体为岩浆热液型,成矿与后碰撞造山作用伸展- 构造转换有关的岩浆作用有关,成矿物质和流体来源于晚泥盆世深部含矿岩浆作用。     

新疆西天山果子沟地区开亚他斯火山机构及成矿潜力浅析

新疆西天山地区的早石炭世古火山机构是形成金矿床的重要构造。本文通过对新疆西天山果子沟地区开亚他斯古火山机构的形成时代、岩石类型、火山岩相、喷发旋回、喷发韵律、成矿条件的调查研究, 初步确定开亚他斯古火山机构形成于331Ma±2Ma(早石炭世), 为一套钙碱性系列岩石组合, 具有爆发相—喷溢相—爆发相的火山活动特征, 火山岩中金、锑、铋、锌、钼元素背景值较高, 有形成阿希火山岩型金床的成矿背景和潜力。      

黑龙江多宝山矿田争光金矿床类型、U-Pb年代学及古火山机构

争光金矿床(伴生锌)位于我国东北地区黑龙江省多宝山Cu-Au-Mo成矿带南东端,构造上处于古亚洲成矿构造域和滨太平洋成矿构造域的叠加部位。该金矿距北西向的多宝山铜金矿和铜山铜矿分别约为10km和5km,因此,深入研究其成矿时代、成因类型归属,理清与多宝山铜金矿-铜山铜矿的关系具有重要科学价值。争光金矿赋矿围岩为奥陶系多宝山组安山质火山岩地层,发育爆发相、溢流相、火山碎屑流相、火山沉积相等,且爆发相和喷溢相交替出现,具有喷发时期熔岩溢流与火山碎屑物的喷发交替进行或具多旋回火山活动的特征;根据火山集块岩、火山角砾岩、火山碎屑岩的空间展布及岩相变化特征,推测矿区内发育有古火山机构。受后期北西向构造影响,火山岩地层具北西向弱定向变形特征。含金脉系呈脉状、网脉状沿北西向、北东向及南北向构造产出;矿石矿物以黄铁矿、闪锌矿、黄铜矿、方铅矿为主,金以裂隙金、粒间金和包裹金的形式赋存于上述硫化物中,部分赋存在石英中。综合脉系特征、矿物组合、蚀变类型、闪锌矿Fe含量等,本文明确提出该矿床为中硫型浅成低温热液型金矿。对矿区内发育的成矿后闪长玢岩、花岗闪长斑岩及长石斑岩等脉岩的锆石U-Pb测年结果初步厘定争光金矿金成矿作用早于454Ma。综合判断争光金矿与多宝山含金斑岩铜矿、铜山铜矿同形成于480~454Ma受古亚洲洋俯冲作用控制的岛弧背景,构成完整的斑岩Cu-Au与中硫化型浅成低温热液Au成矿系统。     

中国东部中生代岩浆岩的时空分布及其与热液型铀矿的关系

中国东部中生代岩浆活动强烈,热液型铀矿分布广泛。空间上,自北而南可划分出大兴安岭、小兴安岭-长白山、冀北-辽西、大别山北缘、长江中下游、扬子陆块东南缘、武夷-云开、东南沿海8个火山-侵入岩带和沽源-红山子、青龙-兴城、庐枞-栖霞、赣杭、武夷山、桃山-诸广、郴州-钦州、湘中、雪峰山-摩天岭9个热液型铀成矿带以及满洲里-额尔古纳、扎兰屯、伊春、金寨、天目山5个铀成矿远景带;时间上,从早到晚可划分出250~230Ma、228~205Ma、195~175Ma、165~150Ma、145~130Ma、126~115Ma、110~100Ma、97~80Ma 8个不同时期的岩浆活动和早期深源高温、晚期浅源低温两个成矿系统,深源高温成矿系统可划分出11个矿床式,浅源低温成矿系统可划分出15个矿床式。勘查成果显示,热液型铀矿对岩浆岩的岩性岩相没有选择性,但与特定时期的岩浆岩有密切的关系,其中与花岗岩有关的热液型铀矿主要赋存在三叠纪花岗岩中,与火山岩有关的热液型铀矿主要赋存在早白垩世早期高钾钙碱性流纹岩-碱性粗面岩组合中,而且晚期高侵位小岩体或火山斑岩体的内、外接触带是有利的赋矿部位。     

Three Palaeoproterozoic basins—Yerrida,Bryah and Padbury—Capricorn Orogen,Western Australia

The Palaeoproterozoic Yerrida, Bryah and Padbury Basins record periods of sedimentation and magmatism along the northern margin of the Archaean Yilgarn Craton. Each basin is characterised by distinct stratigraphy, igneous activity, structural and metamorphic history and mineral deposit types. The oldest of these basins, the Yerrida Basin (ca 2200 Ma) is floored by rocks of the Archaean Yilgarn Craton. Important features of this basin are the presence of evaporites and continental flood basalts. The ca 2000 Ma Bryah Basin developed on the northern margin of the Yilgarn Craton during backarc sea‐floor spreading and rifting, the result of which was the emplacement of voluminous mafic and ultramafic volcanic rocks. During the waning stages of the Bryah Basin this mafic to ultramafic volcanism gave way to deposition of clastic and chemical sedimentary rocks. At a later stage, the Padbury Basin developed as a retroarc foreland basin on top of the Bryah Basin in a fold‐and‐thrust belt. This resulted from either the collision of the Pilbara and Yilgarn Cratons (Capricorn Orogeny) or the ca 2000 Ma westward collision of the southern part of the Gascoyne Complex and the Yilgarn Craton (Glenburgh Orogeny). During the Capricorn Orogeny the Bryah Group was thrust to the southeast, over the Yerrida Group. Important mineral deposits are contained in the Yerrida, Bryah and Padbury Basins. In the Yerrida Basin a large Pb–carbonate deposit (Magellan) and black shale‐hosted gossans containing anomalous abundances of Ba, Cu, Zn and Pd are present. The Pb–carbonate deposit is hosted by the upper units of the Juderina Formation, and the lower unit of the unconformably overlying Earaheedy Group. The Bryah and Padbury Basins contain orogenic gold, copper‐gold volcanogenic massive sulfides, manganese and iron ore. The origin of the gold mineralisation is probably related to tectonothermal activity during the Capricorn Orogeny at ca 1800 Ma.     

内蒙古中部大青山新地沟绿岩带型金矿的成矿时代

内蒙古新地沟金矿床产于大青山太古宙花岗岩-绿岩带中,受色尔腾山群柳树沟组中基性火山岩系和韧性剪切带控制.容矿岩石主要是变安山质-英安质火山岩类.为解决主矿体的形成时代,采用石英40Ar/39Ar法,直接测定了含金石英细脉浸染状矿石中石英的形成时代,结果表明新地沟金矿的形成时代为1991.43～1988.93Ma.由此提出新地沟金矿的成因主要与吕梁期韧性剪切带中的变质变形作用有关.     

西秦岭岗岔金矿赋矿围岩成岩时代及其地质意义

岗岔金矿是在西秦岭西段北缘发现的中型金矿床,有潜力达到大型。该金矿目前发现的5条金矿脉明显受断裂控制,赋矿围岩浅部主要是一套火山岩和火山碎屑岩。该套火山岩长期以来被认为是侏罗系郎木寺组。采用锆石U-Pb法对其中的凝灰岩进行定年测试,结果显示年龄为(245±2) Ma,说明该火山岩不是侏罗系而应该属于三叠系。矿区内与金矿脉空间关系密切的花岗闪长岩和石英闪长岩锆石U-Pb定年结果显示,二者年龄也分别为(242±2) Ma和(246±3) Ma。这说明矿区内侵入体与赋矿围岩属于近乎同时代(印支期)岩浆活动的产物。上述测年结果进一步限定了岗岔金矿形成时间为三叠纪早期,即构造岩浆活动之期后的热液期。该结论为深入认识矿床成因、总结成矿规律和指导勘查方向提供了新的依据。     

黑龙江省东部火山岩型金矿找矿前景浅析

黑龙江省东部中一新生代火山岩（包括次火山岩）大面积分布,它们形成于以前寒武纪变质岩为基底的构造-岩浆活化区,从属于环太平洋火山岩带。资料表明,该区具有寻找火山岩型金矿的良好前景,团结沟大型火山热液金矿床即是范例。本文从地质背景、典型金矿特征、成矿条件及地球化学异常等方面,探讨了该区中一新生代火山岩型金矿的找矿前景并划分出三个成矿远景区。     

对辽宁二道沟金矿床成矿机制的讨论──稀土元素地球化学证据

通过对火山岩、对面沟花岗（斑）闪长岩和金矿石的稀土元素组成及分布模式的研究对比，表明成矿物质来源于二道沟的火山岩系，成矿热液来源于沿火山岩中裂隙下渗的被加热的大气降水来源的地下水，是一典型的浅成低温热液型金矿床     

新疆西天山吐拉苏-也里莫墩火山岩带年代学:对加曼特金矿成矿时代的约束

吐拉苏一也里莫墩火山岩带是西天山北段晚古生代构造一岩浆成矿带的重要组成部分,它严格控制着矿带内金矿床的时空分布.在充分研究前人资料的基础上,本文实测了也里莫墩地区加曼特金矿围岩大哈拉军山组火山岩剖面,发现火山岩地层与矿化关系密切.利用LA-ICP-MS锆石U-Pb方法测定了金矿赋矿围岩(英安岩)的形成时代,其206pb...     

辽宁分水金矿床地质及成因

分水金矿属岩浆期后中温热液(石英脉)型矿床,位于石棚峪超单元北西外接触带上,二者有着密切的空间分布关系.铅同位素特征显示,金矿成矿物质来源于186±13Ma及2800Ma的两个源区.燕山早期阶段,石棚峪超单元黑云母碱长花岗岩中深成侵入活动(186±13Ma)所分异的岩浆期后热液在运移就位过程中萃取了部分围岩(约2800Ma)的成矿物质,稍晚于186±13Ma形成金、铅矿床.     

The Crater Mountain Deposit,Papua New Guinea: Porphyry‐related Au–Te System

Ore mineralization and wall rock alteration of Crater Mountain gold deposit, Papua New Guinea, were investigated using ore and host rock samples from drill holes for ore and alteration mineralogical study. The host rocks of the deposit are quartz‐feldspar porphyry, feldspar‐hornblende porphyry, andesitic volcanics and pyroclastics, and basaltic‐andesitic tuff. The main ore minerals are pyrite, sphalerite, galena, chalcopyrite and moderate amounts of tetrahedrite, tennantite, pyrrhotite, bornite and enargite. Small amounts of enargite, tetradymite, altaite, heyrovskyite, bismuthinite, bornite, idaite, cubanite, native gold, CuPbS₂, an unidentified Bi‐Te‐S mineral and argentopyrite occur as inclusions mainly in pyrite veins and grains. Native gold occurs significantly in the As‐rich pyrite veins in volcanic units, and coexists with Bi‐Te‐S mineral species and rarely with chalcopyrite and cubanite relics. Four mineralization stages were recognized based on the observations of ore textures. Stage I is characterized by quartz‐sericite‐calcite alteration with trace pyrite and chalcopyrite in the monomict diatreme breccias; Stage II is defined by the crystallization of pyrite and by weak quartz‐chlorite‐sericite‐calcite alteration; Stage III is a major ore formation episode where sulfides deposited as disseminated grains and veins that host native gold, and is divided into three sub‐stages; Stage IV is characterized by predominant carbonitization. Gold mineralization occurred in the sub‐stages 2 and 3 in Stage III. The fS₂ is considered to have decreased from ～10^?2 to 10^?14 atm with decreasing temperature of fluid.     

Provenance and tectonic setting of neoproterozoic supracrustal rocks from the Ceará Central Domain,Borborema Province (NE Brazil): constraints from geochemistry and detrital zircon ages

Major- and trace-element and U–Pb analyses of detrital zircons were performed on metavolcano sedimentary sequences and igneous rocks from the Ceará Central Domain (CCD) in the Borborema Province of northeastern Brazil. No significant geochemical differences were found between these rocks, which were possibly initially deposited as parts of a very large metavolcano-sedimentary sequence. Weathering in the source area was moderate, and the sediments were deposited as both sands and clays. The sources of the sediments were likely mixtures of felsic and intermediate rocks deposited predominantly in an active-margin setting with minor contributions of both continental arc and passive margin components. Three main source ages were identified: Palaeoproterozoic (~2.2 Ga), for which potential sources include the Palaeoproterozoic Madalena-Algodões Suite; early Neoproterozoic (~850 Ma), related to felsic volcanic magmatism due to continental rifting, initial phases of the Santa Quitéria Magmatic Arc, or magmatic arc systems on the margins of the Palaeoproterozoic crust; and late Neoproterozoic (~650 Ma), associated with extensive granite generation and migmatization events accompanying Santa Quitéria Arc activity. Deposition of the CCD volcanosedimentary rocks occurred shortly before regional, collision-type metamorphism accompanying the amalgamation of the São Francisco-Congo Cratons (~ 620–630 Ma).     

河南嵩县庙岭金矿地质特征与钾长石~（40）Ar/^（39）Ar定年

河南嵩县庙岭金矿位于华北陆块南缘熊耳山—外方山地区。矿床赋存于中元古界熊耳群火山岩中近南北向断裂带内,矿体呈似层状、透镜状产出,矿石具浸染状、细网脉状构造和微细粒它形粒状晶粒结构、交代结构,围岩热液蚀变有硅化、钾长石化、绢云母化、黄铁矿化等,矿化具有多阶段的特点,属破碎带蚀变岩型金矿。成矿热液蚀变矿物钾长石Ar-Ar法测年的结果：坪年龄为121.6Ma±1.2Ma,等时线年龄为117.0Ma±1.6Ma,表明矿床形成于早白垩世,与熊耳山地区祁雨沟、瑶沟等金矿床形成于同一时期,属与早白垩世构造-岩浆-流体活动有关的产物。     

河南嵩县庙岭金矿地质特征与钾长石40Ar/39Ar定年

河南嵩县庙岭金矿位于华北陆块南缘熊耳山—外方山地区。矿床赋存于中元古界熊耳群火山岩中近南北向断裂带内,矿体呈似层状、透镜状产出,矿石具浸染状、细网脉状构造和微细粒它形粒状晶粒结构、交代结构,围岩热液蚀变有硅化、钾长石化、绢云母化、黄铁矿化等,矿化具有多阶段的特点,属破碎带蚀变岩型金矿。成矿热液蚀变矿物钾长石Ar-Ar法测年的结果：坪年龄为121.6Ma±1.2Ma,等时线年龄为117.0Ma±1.6Ma,表明矿床形成于早白垩世,与熊耳山地区祁雨沟、瑶沟等金矿床形成于同一时期,属与早白垩世构造-岩浆-流体活动有关的产物。     

阿尔泰萨热阔布金矿床的自然铋及其与金矿化关系

萨热阔布金矿是阿尔泰山南缘金一多金属矿带中与断裂变质作用有关的石英脉一蚀变岩型金矿床。本文通过电子探针的研究,在该矿区发现较多的自然铋矿物,它与金矿化关系非常密切,产出于多金属硫化物阶段,与方铅矿、黄铜矿等共生。矿区蚀变岩和矿石的微量元素R型聚类分析表明,Bi与Au相关最密切,Au、Cu、Ag、Bi是主要的成矿元素组合。Bi异常可以作为金矿化的重要指示,自然铋矿物的出现可以作为含金石英脉富矿地段的重要标志。     

The Xitieshan volcanic sediment-hosted massive sulfide deposit,North Qaidam,China: Geology,structural deformation and geochronology

The Xitieshan deposit (~ 64 Mt at 4.86% Zn, 4.16% Pb, 58 g/t Ag, and 0.68 g/t Au) is hosted by the Middle to Late Ordovician Tanjianshan Group of the North Qaidam tectonic metallogenic belt, NW China. This belt is characterized by island arc volcanic, ultra-high pressure (UHP) metamorphic and ophiolitic rocks. The Tanjianshan Group constitutes a succession of metamorphosed bimodal volcanic and sedimentary rocks, which are interpreted to have formed on the margin of a back-arc ocean basin between the Qaidam block and the Qilian block.Four stratigraphic units are identified within the Ordovician Tanjianshan Group. From northeast to southwest they are: 1) unit a, or the lower volcanic-sedimentary rocks, comprising bimodal volcanic rocks (unit a-1) and sedimentary rocks (unit a-2) ranging from carbonates to black carbonaceous schist; 2) unit b, or intermediate-mafic volcaniclastic rocks, characterized by intermediate to mafic volcaniclastic rocks intercalated with lamellar carbonaceous schist and minor marble lenses; 3) unit c, a purplish red sandy conglomerate that unconformably overlies unit b, representing the product of the foreland basin sedimentation during the Early Silurian; 4) unit d, or mafic volcanic rocks, from base to up, comprising the lower mafic volcaniclastic rocks (unit d-1), middle clastic sedimentary rocks (unit d-2), upper mafic volcaniclastic rocks (unit d-3), and uppermost mafic volcanic rocks (unit d-4). Unit a-2 hosts most of the massive sulfides whereas unit b contains subordinate amounts.The massive stratiform lenses constitute most of the Xitieshan deposit with significant amount of semi-massive and irregularly-shaped sulfides and minor amounts in stringer veins. Pyrite, galena and sphalerite are the dominant sulfide minerals, with subordinate pyrrhotite and chalcopyrite. Quartz is a dominant gangue mineral. Sericite, quartz, chlorite, and carbonate alteration of host rocks accompanies the mineralization.U-Pb zircon geochronology yields three ages of 454 Ma, 452 Ma and 451 Ma for the footwall felsic volcanic rocks in unit a-1, sedimentary host rocks in unit a-2 and hanging-wall unit b, respectively. The Xitieshan deposit is considered to be coeval with the sedimentation of unit a-2 and unit b of the Tanjianshan Group. The Xitieshan deposit has been intensely deformed during two phases (main ductile shear and minor ductile-brittle deformation). The main ductile shear deformation controls the general strike of the ore zones, whereas minor deformation controls the internal geometry of the ore bodies. ⁴⁰Ar-³⁹Ar age of muscovite from mylonitized granitic gneisses in the ductile shear zone is ~ 399 Ma, which is interpreted to date the Xitieshan ductile shear zone, suggesting that Early Devonian metamorphism and deformation post-dated the Tanjianshan Group.The Xitieshan deposit has many features similar to that of the Bathurst district of Canada, the Iberian Pyrite Belt of Spain, the Wolverine volcanogenic massive sulfide deposit in Canada. Based on its tectonic setting, host-rock types, local geologic setting, metal grades, geochronology, temperatures and salinities of mineralizing fluid and source of sulfur, the Xitieshan deposit has features similar to sedimentary exhalative (SEDEX) and VMS deposits and is similar to volcanic and sediment-hosted massive sulfide (VSHMS) deposits.     

安徽当涂杨庄铁矿床地质地球化学特征与成因研究

杨庄铁矿床位于宁芜中生代火山岩盆地西南段的钟姑山矿田内,属于宁芜地区玢岩型铁矿中次火山岩体与前火山岩系沉积岩接触带中的铁矿床。该矿床的主矿体呈层状、似层状、透镜状,产于闪长玢岩岩体与徐家山组接触带部位以及闪长（玢）岩岩体内部。矿石矿物主要为磁铁矿、假象赤铁矿,脉石矿物主要为辉石、角闪石、长石、绿泥石、石膏、绢云母等。通过对该矿床地质地球化学特征和控矿因素的研究,认为杨庄铁矿床成矿物质主要来源于岩浆,属于玢岩型热液充填-交代型铁矿床。     

河南省洛宁县三官庙金矿床构造控矿特征

三官庙金矿位于太华群与熊耳群接触带附近的似斑状花岗岩体南侧,矿床明显受断裂构造控制。矿区内拆离断裂带和层间滑脱断裂蚀变带发育,含金蚀变破碎带中的构造岩石为含矿主岩。矿体形态以较稳定的似层状为主,金矿物为银金矿等;金的载体矿物为黄铁矿、石英和方铅矿。围岩蚀变为硅化、黄铁矿化、方铅矿化、绿泥石化和绢云母化等,矿化类型属蚀变岩型金矿。在多期次强烈构造-岩浆活动、区域变质和混合岩化作用过程中,Au元素得以沿层间滑脱断裂蚀变带富集成矿。     

辽宁阜新排山楼金矿的40Ar/39Ar成矿年龄

排山楼大型金矿床产于辽西高级变质太古宙花岗岩-绿岩带中,受绿岩中、上部层位的基性-中酸性火山岩系和东西向韧性剪切带控制。容矿岩石主要是变质安山质-英安质火山岩类。为解决主矿体的形成时代,选取含金石英细脉浸染状矿石中的石英测定了⁴⁰Ar/³⁹Ar年龄为2105.2±10.4Ma。谱线特征为马鞍型,其底坪年龄为石英的结晶年龄。由此提出排山楼金矿的成因主要与吕梁期的东西向韧性剪切带有关。