辽东五龙金矿鸡心岭断裂的年代学约束及其对成矿潜力的指示

五龙金矿是辽东地区形成于早白垩世的代表性石英脉型金矿, 与胶东地区"玲珑式"金矿相似。胶东地区早白垩世金矿受北东向断裂控制且规模宏大, 五龙金矿已知矿体主要赋存于北西向和近南北向断裂内, 其北东向断裂研究程度较低、成矿潜力尚不清楚。针对五龙矿区的鸡心岭断裂开展了地质调查, 对侵位其中的岩脉和热液白云母进行定年, 为断裂内构造-岩浆-热液活动提供年代学约束。调查发现, 鸡心岭断裂整体为脆性变形, 具有多期活动的特征, 依次有煌斑岩、含白云母石英脉和闪长岩脉侵入其中。测年结果显示, 煌斑岩的锆石206Pb/238U年龄加权平均值为132.1±1.7 Ma, 热液白云母的40Ar/39Ar坪年龄为126.8±0.5 Ma, 闪长岩的锆石206Pb/238U年龄加权平均值为112.9±1.4 Ma。年龄数据指示, 鸡心岭断裂在132 Ma之前形成, 在132~113 Ma之间经历了岩浆-热液活动, 依次对应区域上的早白垩世初期北北西-南南东向挤压和早白垩世中期北西-南东向/北西西-南东东向伸展背景。从现有调查程度看, 鸡心岭断裂较胶东地区北东向断裂具有序次低、规模小、构造和流体活动较弱的特征。辽东地区燕山期金矿找矿应注意关注更高序次的低角度断裂, 五龙一带的北东向断裂找矿工作应优先评价断裂走向变化、深部由陡变缓的部位。     

甘肃北山地区拾金坡式岩浆热液型金矿成矿模式建立

通过对拾金坡金矿的区域地质背景和成矿地质环境（含矿地层、控矿构造、侵入岩、矿质来源、含矿热液运移方式及矿体赋存形态等）分析认为：拾金坡金矿床矿质主要来源于拾金坡复式岩体,受断层构造控制,后期构造活动及热液扰动促使了成矿作用的发生。本文总结归纳了主要成矿要素,揭示了典型矿床的成矿规律,并尝试性的建立了拾金坡式岩浆热液型金矿成矿模式,以期指导拾金坡—金场沟侵入岩区金成矿带的矿产勘查与研究。     

广西镇龙山岩浆热液成矿系统——来自成矿流体、成矿物质的证据

镇龙山岩浆热液成矿系统位于广西"山字形构造"前弧一个较大的短轴背斜构成的穹窿中,矿床（点）主要赋存于寒武系和泥盆系碎屑岩中。为探讨各矿床（点）之间的成因联系,在野外调查的基础上,对典型矿床进行了流体包裹体测温、激光拉曼及氢-氧-硫同位素研究。研究结果表明,包裹体主要为水溶液、气液两相包裹体,且含CO2和CH4包裹体较多,偶见含NaCl子晶的包裹体。高温矿床均一温度为320~339℃,盐度为8%~9% NaCl eqv;中温矿床均一温度为280~299℃,盐度为7%~8% NaCl eqv;低温矿床均一温度为160~179℃,盐度为5%~6% NaCl eqv。石英中流体包裹体δDV-SMOW集中在-55‰~-80.1‰之间,δ18OV-PDB集中在-9.1‰~-18.8‰之间,氢-氧同位素图解主要落在岩浆水的范围内,并有向大气降水偏移的趋势,表明上述矿床流体的主要来源可能是岩浆水,后期有大气降水的混入。单矿物的硫同位素峰值集中在-2‰~2‰之间,其中毒砂以正值为主,辉锑矿以负值为主,总体具有相对均一的硫源,说明硫化物中的硫均来自岩浆。上述研究表明,镇龙山地区矿床（点）分布具有明显的岩浆-热液成矿系统的分带特点,岩体及其边缘发育斑岩型高温热液矿床,外围逐渐过渡到中温和中低温热液矿床,建立了镇龙山地区岩浆热液成矿系统的水平和垂直矿化分带模型。     

辽东三股流岩体是否为五龙金矿成矿提供必要的能量？

辽东地区五龙金矿是华北克拉通东部一个典型的石英脉型金矿床,其成矿过程尚存争议.多种证据表明五龙金矿成矿流体属于岩浆热液,成矿时代又与距离较近的三股流岩体的侵位年龄接近,因而有一种观点认为二者密切相关.目前尚未有充足的地质证据表明三股流岩体释放了五龙金矿成矿所需要的含金岩浆热液,那么三股流岩体是否为其提供必要的能量呢？利用现有的地球化学和地球物理数据,建立三股流岩体仅作为热源驱动大气降水和释放岩浆热液的对流数值模型,模拟三股流岩体周边的流场和温度场.数值模拟结果表明,三股流岩体自侵位后可在其周边1 km范围内形成300℃以上的热场,并维持数十万年,因而有利于形成岩浆热液型矿床.然而,五龙金矿所在的位置受三股流岩体侵位后的热场影响不显著.如果三股流岩体释放了充足的岩浆热液,岩浆热液可在岩体边缘和接触带形成热液蚀变和金矿化,这与现有的地质证据不符.故五龙金矿可能与三股流岩体没有直接成因关系,而金成矿热液来源仍需深入研究.      

北山拾金坡—金场沟金成矿带岩浆热液型金矿区域成矿模式的建立

拾金坡—金场沟金成矿带是北山地区最重要的金成矿带之一,成矿带内已发现金矿化线索38处,中小型金矿床9处,均与中酸性岩浆岩有关,主要成矿类型有岩浆热液型和矽卡岩型,其中岩浆热液型金矿是成矿带最主要的成矿类型。优选拾金坡金矿床和金场沟金矿床作为拾金坡式金矿的典型矿床,通过分析矿床的成矿地质环境、矿体特征、矿床成因和成矿模式等,建立了成矿带区域成矿模式。成矿模式的建立,将有助于促进对矿床成矿规律的认识,明确该成矿带金矿找矿方向。     

辽宁省五龙金矿床成岩成矿年代学及同位素地球化学特征

五龙矿床是中国辽东地区最大的石英脉型金矿床,赋存于中生代黑云母花岗岩中。金矿体多呈脉状产出,与中生代细粒闪长岩有成因联系。文章采用LA-ICP-MS锆石U-Pb定年方法,获得矿区内黑云母花岗岩、花岗斑岩、细粒闪长岩的结晶年龄分别为(155.4±0.9)Ma、(154.2±1.2)Ma、(123.1±0.9)Ma。文章选取金矿石中绢云母样品开展了Ar-Ar定年,获得Ar-Ar坪年龄为(122.8±0.8)Ma(MSWD=0.09)。金属硫化物的δ34S值介于+1.1‰~+2.4‰,平均值为+1.8‰,表明硫主要来自深源岩浆。黄铁矿中流体包裹体3He/4He比值为0.36~0.65Ra,平均值为0.50 Ra,表明地幔流体参与成矿作用的比例为3.9%~7.2%,地壳流体占主导地位。五龙金矿的成矿时代为早白垩世,形成于华北克拉通东部的构造体制转折和大规模岩石圈减薄背景。     

晓天-磨子潭火山岩盆地与碱性岩相关的浅成低温热液型金矿成矿模型初构

北淮阳成矿带东段安徽霍山县晓天-磨子潭火山岩盆地自西向东产出隆兴金矿、戴家河金矿、东溪金矿、南关岭金矿等一系列浅成低温热液型金矿床。作者在充分收集、消化吸收以往各矿床勘查报告、区调报告及最新科研成果的基础上,结合野外考察,对矿床成矿作用与成矿地质体、控矿构造及成矿地质作用特征标志进行系统总结,初步认为晓天-磨子潭火山岩盆地金矿是与碱性岩相关的浅成低温热液型金矿,并初步构建本地区成矿模型。以期抛砖引玉,为该地区下步金矿勘查工作提供新的思路。     

Genesis of the Wulong gold deposit,Liaoning Province,NE China:Constrains from noble gases,radiogenic and stable isotope studies

TheWulong lode deposit contains over 80 tonnes of gold with an average grade of 5.35 g/t.It is one of the largest deposits in Dandong City,Liaoning Province in northeast China.Previous studies on the deposit focused on its geological characteristics,geochemistry,fluid inclusions,and the timing of gold mineralization.However,controversy remains regarding the origin of the ore-forming fluids and metals,and the genesis of the gold deposit.This paper presents zircon UePb and pyrite RbeSr ages and S,Pb,He,and Ar isotopic results along with quartz H and O isotopic data for all litho-units associated with the deposit.Laser ablation inductively coupled mass spectrometry measurements yielded zircon UePb dates for samples of pre-mineralization rocks like granite porphyry dike,the Sanguliu granodiorite,fine-grained diorite,and syn-mineralization diorite,as well as post-mineralization dolerite,and lamprophyre;their emplacement ages are 126
1 Ma,124
1 Ma,123
1 Ma,120
1 Ma,119
2 Ma,and 115
2 Ma,respectively.The pyrite RbeSr isochron age is 119
1 Ma,indicating that both magmatism and mineralization occurred during the Early Cretaceous.The d18OH2O values of ore-forming hydrothermal fluids from the quartzepolymetallic sulfide vein stage vary from 4.8&to 6.5&,and the dDV-SMOW values are between67.7&and75.9&,indicating that the ore-forming fluids were primarily magmatic.The noble gas isotope compositions of fluid inclusions hosted in pyrite suggest that the ore-forming fluids were dominantly derived from crustal sources with minor mantle input.Sulfur isotopic values of pyrite vary between 0.2&and 3.5&,suggesting that S was derived from a homogeneous magmatic source or possibly from fluids derived from the crust.The Pb isotopic compositions of sulfides(207Pb/204Pb?15.51 e15.71,206Pb/204Pb?17.35e18.75,208Pb/204Pb?38.27e40.03)indicate that the Pb of the Wulong gold deposit is a mixture of crust and mantle components.Geochronological and geochemical data,together with the regional geological history,indicate that Early Cretaceous magmatism and mineralization of the Wulong gold deposit occurred during the rollback of the subducting Paleo-Pacific Plate,which resulted in lithospheric thinning and the destruction of the North China Craton(NCC),which indicates that the deposit is of magmaticehydrothermal origin.     

辽宁五龙金矿构造叠加晕研究

五龙金矿是辽东矿集区的大型石英脉型金矿床,累计黄金储量超过80吨,平均品位为5.35g/t。随着开采量的增加,目前该矿床开采深度达近千米,保有储量不断减少,步入危机矿山行列,急需开展矿区深部找矿预测研究,实现寻找深部盲矿的有效突破。本次研究在前人研究工作的基础上,分析五龙金矿床矿石微量元素地球化学特征,运用相关分析、聚类分析、因子分析等多元统计方法,对五龙金矿构造叠加晕进行了系统研究。结果显示,五龙金矿成矿过程具有多期次和多阶段的特征,各指示元素在矿体轴向上具有前缘晕、近矿晕、与尾晕相互叠加的现象,该现象是深部盲矿预测的重要依据,反映了深部有盲矿存在的可能性。     

新疆吐拉苏盆地京希-伊尔曼德金矿地质和地球化学特征研究

京希-伊尔曼德金矿位于新疆北天山吐拉苏盆地的西北缘,赋存于泥盆纪-早石炭世火山-沉积地层底部的凝灰岩、凝灰质砂岩中,围岩经历了绢云母化、黄铁矿化、多期硅化和角砾化、碳酸盐化和重晶石化,金矿化与硅化围岩紧密伴生。矿体呈透镜状、层状和似层状,产状与围岩基本一致,主要由热液角砾岩型矿石组成,其热液演化期由四个阶段组成:I:硅化及绢云母化——在围岩凝灰岩和凝灰质砂岩中形成大量浸染状石英、绢云母和少量黄铁矿;II:角砾化及硅化——形成含金热液角砾岩a,角砾为早期蚀变围岩,胶结物为烟灰色玉髓状石英、黄铁矿、毒砂和少量金矿物;III:角砾化及硅化——形成含金热液角砾岩b,角砾为热液角砾岩a和蚀变围岩,胶结物为细粒石英、黄铁矿、毒砂和少量金矿物;IV:方解石-重晶石阶段——形成大量粗大的方解石-重晶石脉。京希-伊尔曼德金矿成矿流体本身富集V、Cr、Ni、Cu、Sb,且其中的Mn、Co、Zn、Bi以及大离子亲石元素LILE主要来自火山岩围岩。从成矿早期到晚期,成矿流体轻稀土元素逐渐富集、氧化性增强。水-岩体系氢、氧同位素组成模拟计算表明,京希-伊尔曼德金矿成矿流体主要为与区内火山岩再平衡的岩浆水,其中金浓度为1×10-6～2×10-6,形成该矿需要约1×108～0.5×108t岩浆热液,蚀变围岩和矿石中黄铁矿富集轻稀土元素。角砾化作用及其伴随的氧逸度升高是导致金沉淀的主要机制。     

南澜沧江带勐满热泉型金矿床成矿作用:热液蚀变与元素地球化学制约

勐满金矿床是西南三江特提斯造山带迄今为止报导的为数不多的热泉型金矿床之一,也是南澜沧江带唯一发现的该成因类型的金矿床。然而目前对勐满金矿床热液蚀变特征的分析不足和地球化学数据的缺乏,一直制约着对其成矿过程的深入理解。勐满金矿床原生矿体产于早古生代澜沧群曼来组片岩和侏罗纪花开左组碎屑岩不整合面附近,断裂构造导流、控矿作用显著。矿区两类围岩均发生强烈蚀变,但蚀变类型简单,仅为硅化和高岭土化,与金成矿密切相关。热液高岭土化的大量发育,反映围岩中的长石等含铝矿物与呈酸性的流体发生作用。全岩微量元素组成对比研究表明,近矿围岩蚀变过程中未发生明显的微量元素迁移。镜下观察到Au与黄铜矿等金属硫化物共生,元素相关性分析显示Au与Ag、Cu、Pb、As、S、Sb等元素有正相关趋势,表明它们由统一热液系统携带并发生卸载。在弱酸性成矿流体中,Au主要以金硫络合物的形式进行迁移。当含Au流体运移至地层不整合面附近时,与围岩反应并发生强烈高岭土化,导致流体中的SiO_2和高岭石含量急剧增加,逐渐在矿区导流断裂中沉淀下来。断裂变窄甚至封闭,流体内压持续升高,最终发生爆破,成矿流体强烈减压沸腾,引发金硫络合物失稳,Au发生卸载并沉淀。该过程反复多次发生,形成了矿区含金硅质角砾岩及蚀变岩型矿石。     

40Ar/39Ar dating of the Jiehe gold deposit in the Jiaodong Peninsula,eastern North China Craton: Implications for regional gold metallogeny

The Jiehe gold deposit, containing a confirmed gold reserve of 34 tonnes (t), is a Jiaojia-type (disseminated/stockwork-style) gold deposit in Jiaodong Peninsula. Orebodies are hosted in the contact zone between the Jurassic Moshan biotite granite and the Cretaceous Shangzhuang porphyritic granodiorite, and are structurally controlled by the NNE- to NE-striking Wangershan-Hedong Fault. Sulphide minerals are composed predominantly of pyrite with lesser amounts of chalcopyrite, galena, and sphalerite. Hydrothermal alteration is strictly controlled by fracture zones, in which disseminated sulfides and native gold are spatially associated with pervasive sericitic alteration. Mineralogical, textural, and field relationships indicate four stages of alteration and mineralization, including pyrite-bearing milky and massive quartz (stage 1), light-gray granular quartz–pyrite (stage 2), quartz–polysulfide (stage 3) and quartz–carbonate (stage 4) stages. Economic gold is precipitated in stages 2 and 3.The Jiehe deposit was previously considered to form during the Eocene (46.5 ± 2.3 Ma), based on Rb-Sr dating of sericite. However, ⁴⁰Ar/³⁹Ar dating of sericite in this study yields well-defined, reproducible plateau ages between 118.8 ± 0.7 Ma and 120.7 ± 0.8 Ma. These ⁴⁰Ar/³⁹Ar ages are consistent with geochronological data from other gold deposits in the region, indicating that all gold deposits in Jiaodong formed in a short-term period around 120 Ma. The giant gold mineralization event has a tight relationship with the extensional tectonic regime, and is a shallow crustal metallogenic response of paleo-Pacific slab subduction and lithospheric destruction in the eastern NCC.     

Gold mineralizing efficiency during hydrothermal alteration of the Mesozoic granitoids in the northwest Jiaodong Peninsula: Contrasting conditions between the Guojialing and Linglong plutons

Mesozoic granitoids were extensively altered by hydrothermal fluids in the northwest Jiaodong Peninsula, and gold precipitated from the fluids developing prevalent mineralization in this district. The 160–158 Ma Linglong granite and 130–120 Ma Guojialing granodiorite are the major Mesozoic granitoids in this district, both of which are hydrothermally altered and intimately associated with gold mineralization. Although numerous studies were carried out by previous researchers, mainly focusing on tectonics, lithology, mineralogy, geochronology, and fluid geochemistry, knowledge about hydrothermal alteration processes of these granitoids and their gold mineralization efficiency (i.e. which one is more effective to precipitate the gold from its parent solution) is far beyond clear illumination. Geochemical simulation software GEM-Selektor (based on the Gibbs energy minimization algorithm) was applied in this study, which aims to test the gold mineralization efficiency of these two granitoids during the hydrothermal alteration processes. Simulation results indicate that solutions in equilibrium with the Linglong granite are capable of hosting more sulfur than that with the Guojialing granodiorite, since the latter contains more Fe. However, the solutions with these two granitoids display similar gold solubility. “Bulk cooling” simulation results show that the gold mineralization pattern is similar between the Linglong and Guojialing case; “Rock titration” simulation results reveal that the Guojialing granodiorite is prone to precipitate gold more strongly than the Linglong granite, as gold-bearing solutions (or ore-forming fluids) flowing-through at high temperature, equivalent to a deeper level, implying that if the gold mineralization is developed at depth, the Guojialing rock will precipitate more gold. If the gold-bearing solution flow-through the wall rocks relatively fast, and gold mineralization fails to take place, then the Guojialing granodiorite is probably unfavorable for subsequent gold enrichment of the ore-forming fluid. The Linglong granite will precipitate the gold more efficiently from its parent solution at low temperature or at a shallower level, and this is consistent with previous mining prospecting results. Therefore, we suggest that the Guojialing granodiorite should be treated as the main target during future deep prospecting project.     

钍石电子探针定年：记录小秦岭矿集区伟晶岩热液蚀变历史

电子探针化学定年法 (Chemical Th-U-total Pb Isochron Method,CHIME) 以其原位、极高的空间分辨率、样品制备简单方便、不破坏样品、测试速度快、成本低等优点,被成功用于独居石、褐帘石、锆石、磷钇矿、晶质铀矿等副矿物定年,但应用于钍石定年仍不成熟。本文尝试利用电子探针对小秦岭矿集区元古宙伟晶岩脉中的钍石进行定年。显微镜下观察发现,热液钍石颗粒细小（<30 μm）,多与独居石共生,包裹在褐帘石中。我们对未发生蚀变或者蜕晶化的小颗粒钍石进行了电子探针Th-U-Pb化学法定年,得到的加权平均年龄为120.9±2.1 Ma (95%置信区间)。这一年龄与枪马金矿的矿化年龄一致,代表了继该地区大规模花岗岩侵位活动之后,华北克拉通减薄过程中的又一次热液蚀变过程。     

辽东地区王家崴子金矿古元古代金预富集矿化事件

王家崴子金矿床位于辽东半岛猫岭金矿集区内, 为一中型石英脉型金矿床。矿体产于古元古代辽河群盖县组地层中, 主要受控于区内一系列近平行的NW向韧性剪切带。本文选择与金密切共生的黄铁矿、闪锌矿和方铅矿为研究对象, 采用LA-(MC)ICP-MS原位微区分析技术, 开展原位S-Pb同位素和微量元素特征研究。S同位素测试结果显示王家崴子金矿床硫化物δ³⁴S值为8.2‰~11.5‰, 明显高于典型岩浆硫值范围, 与盖县组地层硫范围重叠, 推断可能主要来源于地层硫。王家崴子金矿床硫化物的²⁰⁸Pb/²⁰⁴Pb、²⁰⁷Pb/²⁰⁴Pb和²⁰⁶Pb/²⁰⁴Pb值分别为39.000~39.084、15.691~15.707和18.623~18.664, 落在上地壳演化线附近且在盖县组地层范围内, 表明上地壳地层围岩盖县组是王家崴子金矿床重要的Pb源。LA-ICP-MS微量元素分析显示黄铁矿具有低的Co/Ni和Te/Au比值, 明显富集Au、As、Ag、Cu、Pb和Zn等元素, 指示了其为沉积热液成因黄铁矿。综合前人有关盖县组地层及矿区岩浆岩研究结果, 本文认为该地区可能存在着一期古元古代金预富集作用, 而晚期的早侏罗世岩浆热液活动大量萃取了盖县组地层中早期预富集的成矿物质形成了王家崴子金矿。盖县组地层是辽东地区金成矿重要的矿源层, 需在今后的找矿勘查工作中给予重视。