Pb Isotope Compositions of Shibaqinghao Gold Deposit in Central Inner Mongolia, China

There are two types of gold ore in Shibaqinghao gold deposit, a mylonite ore and a quartz - vein ore. Pb isotope compositions for mylonite ore are characterized by lower Pb isotope ratios ranging from 16.63 to 17.45 (206Pb/204Pb), 15.31 to15.48 (207Pb/204pb), 36.52 to 38.85 (208Pb/204Pb). They are scattered very close to a model curve of the mantle evolution. These ratios suggest that gold in the mylonite ore might be derived from the country rocks, which originated directly in the upper mantle. Pb isotope compositions for quartz - vein ore are characterized by higher Pb isotope ratios ranging from 18.23 to 19.74 (206Pb/204Pb), 15.69 to 15.89 (207Pb/204Pb), 38.64 to 40. 13 (208Pb/204Pb). They are scattered very close to a model curve of the upper crustal evolution. These facts indicate that the gold in the quartz - vein ore might be related to some granitic magma generated in the crust.     

Pb Isotope Compositions of Shibaqinghao Gold Deposit in Central Inner Mongolia,China

There are two types of gold ore in Shibaqinghao gold deposit, a mylonite ore and a quartz - vein ore. Pb isotope compositions for mylonite ore are characterized by lower Pb isotope ratios ranging from 16. 63 to 17.45 (206Pb/204Pb) , 15. 31 tol5.48 (207Pb/204Pb) , 36.52 to38.85 (208Pb/204Pb). They are scattered very close to a model curve of the mantle evolu-tion. These ratios suggest that gold in the mylonite ore might be derived from the country rocks, which originated directly in the upper mantle. Pb isotope compositions for quartz - vein ore are characterized by higher Pb isotope ratios ranging from 18.23 to 19.74 (206Pb/204Pb) , 15. 69 to 15. 89(207Pb/204Pb) , 38. 64 to 40. 13 (208Pb/204Pb). They are scattered very close to a model curve of the upper crustal evolution. These facts indicate that the gold in the quartz - vein ore might be relat-ed to some granitic magma generated in the crust.     

Sulphur Isotope Compositions of Shibaqinghao Gold Deposit in Central Inner Mongolia, China

Shibaqinghao gold deposit is situated in the western part of the northern margin of the North China Craton. It is controlled by an E - W trending tectonic zone that is located in the middle unit of Dongwufenzi group which consists of a sequence of greenschist - facies metamorphic rocks in an Archean greenstone belt.In Shibaqinghao gold deposit there are two types of gold ore, a mylonite ore and a quartz vein ore. Mylonite ore bodies were formed during ductile shearing stage in the Early Proterozoic, whereas quartz vein ore bodies might have been formed in the Mesozoic time.Pyrite accompanied with native gold in the mylonite ore has sulpfur of which δ34S values range from - 5.8 to + 0.8 per mil, similar to the values of mantle- derived sulphur. These data suggest that gold in the mylonite ore be derived from the country rocks which originated directly in the upper mantle.Pyrite in quartz vein ore has the δ34 S values between + 3.0 and + 11.0 per mil, similar to the values of some granitic rocks. These facts indicate that the gold in the quartz vein ore is related to some granitic magma generated in the crust.This study revealed that two different mineralization occurred at different geological times and in different environments but in the same place, resuling in the Shibaqinghao gold deposit.     

西南印度洋中脊热液硫化物成矿物质来源探讨:同位素证据

报道了西南印度洋中脊47°E~55°E洋脊段热液区硫化物中He、Pb和Cu同位素特征,探讨了热液硫化物成矿物质来源特征。结果表明:硫化物N(3 He)/N(4 He)值变化范围较大(R/Ra=0.85~7.02),显示洋中脊玄武岩和海水对He来源具有不同贡献,硫化物中He主要来源于洋中脊玄武岩,也有部分放射性成因He的混入;热液硫化物Pb同位素比值变化范围很小(N(206 Pb)/N(204Pb)=18.196~18.239,N(207 Pb)/N(204 Pb)=15.479~15.490和N(208 Pb)/N(204 Pb)=37.951~38.023),与西南印度洋中脊玄武岩Pb同位素比值较大的变化范围相比,热液流体循环过程中Pb同位素发生了明显均一化;硫化物单矿物Cu同位素组成均为正值(δ(64 Cu)=(0.02~0.52)×10-3),显示西南印度洋中脊热液硫化物呈现略微富集Cu重同位素特征;西南印度洋中脊热液硫化物中He、Pb和Cu同位素记录了热液喷口流体和金属源区特征,热液硫化物成矿物质主要来源于洋中脊玄武岩和海水,但明显经历了热液流体再循环和后期改造过程。     

扬子板块北缘马元铅锌矿床有机地球化学特征及成矿作用

近年来,有机质与金属成矿关系研究备受关注。扬子板块北缘马元矿床铅锌矿体分布与古油藏、沥青在空间上叠置,是探索有机质与铅锌成矿关系的理想地区。矿区发育分散有机质、沥青、气态烃类等不同赋存形式的有机质,生物标志化合物特征明显,以低碳数正构烷烃为主,具浅海环境藻类来源特征,均处于过成熟演化程度。沥青²⁰⁶ Pb/²⁰⁴ Pb值为17.946~18.071,207 Pb/204 Pb值为15.593~15.703,²⁰⁸ Pb/²⁰⁴ Pb值为37.812~38.072,Pb模式年龄为612~478 Ma,结合油-源对比结果,沥青主要来源于下寒武统郭家坝组烃源岩,郭家坝组烃源岩经历了较强的还原环境和缺氧的高盐度环境。各类有机质C同位素组成一致,δ¹³ C值为-35.3‰~-31.4‰,与区内闪锌矿流体包裹体中甲烷、乙烷等C同位素一致,显示有机成因碳典型特征。综上所述,马元铅锌矿床成矿与有机质关系密切,古油藏热裂解和热化学硫酸盐还原(TSR)作用提供了还原硫,富含Pb、Zn的盆地卤水与富含CH₄、H₂S的有机还原性流体混合是其重要成矿机制。     

Metallogenic origin of Sipingshan hot spring gold deposit in Hulin of Heilongjiang and its metallogenic mode

Sipingshan gold deposit is gold-bearing sillcalite in type. There only exist a few kinds of sulfide in the ore and it is lower in content. The gold degree is lower. Au is closely related to the Ag,Cu,Pb,As and Hg elements. The upper sillcalite has Eu and Ce negative anomaly,and the lower sillcalite has Eu positive anomaly. however,the hot spring cemented breccia and rhyolite porphyry have Eu negative anomaly;the S isotope component has deep-seated magmatic sulfur and terrestrial sulfate characteristic;and the Pb isotope has the character of the mixture origin of crust and mantle that is mainly dominated by Pb in the orogenic belt. The ore-forming fluid temperature is 180℃-244℃,characterized by magmatic hydrothermal and meteoric water;and the ore-forming age is 87 Ma. The deposit was formed by the metallogenic fluid in the tectonic fault zone overflowing near the earth’s surface and leading to the metallogenic function and the metallogenic substance deposition.     

新疆彩霞山铅锌矿床地质及同位素地球化学特征

对彩霞山铅锌矿床矿石矿物和围岩的硫、铅同位素及脉石矿物的氢、氧同位素地球化学特征进行了研究。分析结果显示,成矿物质来源于地壳和地幔的混合;硫来源主要为同化了海水硫酸盐的岩浆硫,并有少量生物还原硫参与。氢、氧同位素指示成矿流体早期可能有岩浆热液,主成矿期主要是地层中的建造水参与成矿。     

Petrogenesis of Paleoproterozoic diorite porphyries in Luojiazhuang,western Shandong:constraints from LA-ICP-MS zircon U-Pb geochronology and geochemistry

Based on the study of LA-ICP-MS zircon U-Pb geochronology and whole-rock geochemistry for the Luojiazhuang diorite porphyries in Menying,western Shandong,the analyzed zircons exhibit oscillatory growth zoning in the cathodoluminescence images and have high Th / U ratios( 0. 15--1. 53),indicating a magmatic origin. In addition,most of the zircons have narrow metamorphic edges,suggesting that late metamorphic events may exist. The youngest group of magmatic zircon207 Pb /206 Pb ages ranging from 2 384 Ma to 2234 Ma,yielding a weighted mean age of 2353 ± 14 Ma,which represents the forming age of the diorite porphyries,as the Early Paleoproterozoic. Geochemically,the samples are characterized by low SiO_2( 54. 54% and 55. 47%),high MgO( 5. 22% and 5. 49%) and Mg~#values( 58 and 59). Moreover,they show enrichment of light rare earth elements and large ion lithophile elements( Rb,Ba and K),depletion of heavy rare earth elements and high field strength elements( Nb,Ta,Zr and Hf),positive anomaly of Pb,and negative anomaly of Ti. The fact implies that the Luojiazhuang diorite porphyries might derive from partial melting of enriched lithospheric mantle and mixed with an amount of continental crust material. In summary,they may form in the compression tectonic setting that stretching along the east-west direction at the North China Craton in the Early Paleoproterozoic.     

内蒙古白音诺尔铅锌矿铅同位素研究

内蒙古白音诺尔铅锌矿床是大兴安岭地区储量最大的铅锌矿床,矿体主要沿花岗闪长(斑)岩与大理岩接触带产出。为了查明成矿物质来源,对矿石中的硫化物和矿区内及外围主要侵入岩开展了铅同位素示踪分析。测试结果表明:矿石中硫化物的N(206Pb)/N(204Pb)为18.266～18.372,平均值18.296,N(207Pb)/N(204Pb)为15.501～15.579,平均值15.536,N(208Pb)/N(204Pb)为38.016～38.339,平均值38.138。铅同位素年龄校正计算结果表明:矿石中硫化物的Pb同位素比值与大理岩和花岗闪长(斑)岩非常相似,表明矿石中的铅主要来自花岗闪长(斑)岩和大理岩,说明成矿物质也主要来自这两类岩石,进一步证明了白音诺尔铅锌矿床的成矿与花岗闪长(斑)岩和大理岩有关,属于矽卡岩型矿床,与喷流沉积型和火山岩块状硫化物矿床有明显的差别。与区域上其他银多金属矿床对比发现,本区银多金属矿床的Pb同位素组成非常相似,其组成范围多有重叠,暗示这些矿床的矿石铅来源也非常相似,可能表明有一个共同的富银的基底或地层为这些银多金属矿床的形成提供了成矿物质来源。     

Zircon U-Pb geochronology and geochemistry of Early Cretaceous granodiorite porphyries in Hutouya,western Shandong and their implications for petrogenesis

Zircon LA-ICP-MS U-Pb age and whole-rock geochemistry data are presented for the Hutouya granodiorite porphyries in Mengyin,western Shandong,to restrict its petrogenesis.The analyzed zircons exhibit oscillatory growth zoning and core-rim textures in the cathodoluminescence images and have high Th/U ratios( 0.04--1.66),indicating its magmatic origin.The youngest group of magmatic zircon yields weighted mean~(206)Pb/~(238) U age of 132 ± 2 Ma,which represents the forming age of the granodiorite porphyries,i.e.,the Early Cretaceous.The oldest group of magmatic zircon~(207)Pb/~(206) Pb ages ranges from 2 398 Ma to 2 370 Ma,yielding a weighted mean age of 2 389 ± 23 Ma,suggesting that the basement of the North China Craton should exist in the research area.Geochemically,the samples are characterized by high Si O_2( 70.38% and 64.87%),low Mg O( 0.60% and 1.53%) and Mg~#values( 42.92 and 50.42).Moreover,they show enrichment of light rare earth elements and large ion lithophile elements( e.g.Rb,Ba and K),depletion of heavy rare earth elements and high field strength elements( e.g.Nb and Ta),positive anomaly of Pb,and negative anomaly of Ti.These results,together with previously published data,indicate that the Hutouya granodiorite porphyries were derived from partial melting of a delaminated lower continental crust and subsequent interaction with the mantle peridotites.They are consistent with the period of lithospheric thinning beneath the eastern North China Craton and may be formed in an extensional tectonic environment.     

Ore-forming fluid characteristics and genesis of vein-type lead-zinc mineralization of Xiaohongshilazi deposit,Jilin Province,China

The Xiaohongshilazi mineral deposit in Jilin Province,China,is located in the accretion zone in the northern margin of the North China Block. The deposit contains two types of ore bodies: layered Pb-Zn ore bodies in volcanic rock and vein-hosted Pb-Zn ore bodies controlled by fractures. The vein Pb-Zn ore bodies are strictly controlled by tectonic fracture zones trending in S-N direction,which comprise sulfide veins or sulfidebearing quartz veins distributed along faults or structural fissures. The ores mainly appear mesh-vein and vein structures,and also show solid-solution separation and metasomatic textures. The metal minerals are mainly sphalerite,galena,and pyrite,etc. Wall-rock alteration includes mainly sericitization,chloritization,silicification and carbonatization,etc. Microscope observations and Raman spectroscopy analyses indicate that the oreforming fluid of the vein Pb-Zn ore bodies was mainly magmatic water with low temperature,low salinity,and a shallow depth of metallogenesis( ~ 1.5 km). Sulfur and lead isotope analyses indicate that the sulfide source is mainly formation sulfur or biogenic sulfur,which is similar to the sulfur source of hydrothermal deposit( negative( δ~(34) S values),while the main Pb source was the upper crust with some mantle input. This article argues that the vein Pb-Zn ore body of the Xiaohongshilazi deposit is a low-to medium-temperature hydrothermal vein type related to the formation of a shallow magma chamber.     

韧性剪切带变形特征及控金机制——以丹东四道沟金矿为例

四道沟金矿位于丹东韧性剪切带中部。矿区出露岩石多为构造岩,依据变形强度可分为未变形残块(变质长石石英砂岩)、初糜棱岩(糜棱岩化变砂岩)、糜棱岩(主要是绢云石英糜棱岩)和超糜棱岩四类,横穿剪切带这四类岩石多次出现、规律组合。矿体产出的位置、形态以及矿化类型均受控于这几类岩石的空间分布格式。四道沟金矿的矿体产于中等变形程度的鳞片状构造带中,其上盘实际为一个巨大的变砂岩透镜体,它起了“封闭”的作用,使含金流体在其下盘聚集、沉淀,而鳞片状构造带下盘由糜棱岩和超糜棱岩组成的强变形带可透性好,为含金流体来源通道。在此基础上总结出韧性剪切带控金机制——金活化、迁移通道和聚集空间。     

新疆西滩低温浅成热液金矿床

西滩金矿床是近年西安工程学院发现的重要金矿床之一。该矿床是以含金玉髓质石英为基本矿石建造的脉状热液矿床，成矿物质来源于幔源火山岩（ 石炭系安山岩），成矿流体中Ｈ２Ｏ 主要为大气降水，岩浆活动是成矿流体起源及演化成矿的热动力；成矿温压条件均较低，从矿物组合及成矿学特点，把该矿床归为火山岩区冰长石绢云母型低温浅成热液矿床；但特殊之处是成矿作用发生在碰撞造山过程中，与岛弧安山岩的成岩年龄有较大差别。     

内蒙古克什克腾旗毛盖吐锡矿点LA-ICP-MS锡石U-Pb年龄及地质意义

毛盖吐锡矿点为北京矿产地质研究院在大兴安岭南段新发现的矿点, 位于内蒙古克什克腾旗境内。矿点地处大兴安岭中南段多金属成矿带, 矿化类型为锡石石英脉型。矿石矿物主要为锡石和少量闪锌矿、方铅矿、黄铜矿以及银的矿物, 脉石矿物主要为石英以及少量的萤石。该矿由于首次发现, 研究程度较低, 关于其矿床成因、成矿时代等规律尚不明确。大兴安岭中南段多金属成矿带上发育多个锡多金属矿床, 目前的研究表明这些锡多金属矿床的成矿年龄多集中在早白垩世, 成因与早白垩世花岗岩相关。为了研究毛盖吐锡矿与区域锡多金属成矿作用的联系, 开展了对毛盖吐锡矿点成矿时代的研究, 本研究选取1件石英脉型锡矿石样品进行LA-ICP-MS锡石U-Pb定年, 获得锡石的207Pb/206Pb-238U/206Pb谐和年龄为130.2±3.4 Ma(MSWD=2.9), 表明毛盖吐锡矿点形成于早白垩世, 这与区域上主要的锡多金属矿床成矿时代一致, 说明在大兴安岭中南段寻找锡多金属矿床拥有很好的前景。      

辽西火山岩型金矿地质特征及成因讨论

辽西火山岩型金矿分布在中生代陆相火山盆地边缘活动带内,受辽西弧形构造带控制,为火山期后热液矿床,可初步划分为3种成因类型:次火山(斑岩)热液型(二道沟式),火山—次火山热液型(红石砬子式)和爆发角砾岩型(水泉式),成矿作用与中酸性火山—次火山岩关系密切,成矿时代为燕山期(90—110Ma)。稳定同位素研究结果表明,含矿热液为富含挥发组份和多金属成矿元素的富金水溶液,来源于地壳深部或上地幔,即高温热卤水对镁铁质、超镁铁质岩石长期侵蚀、淋滤和溶解,获取大量的金属成矿元素,在不透水层之下形成深部液态矿源层。     

沂沭断裂带构造活动与胶东金矿形成关系之探讨

在对沂沭断裂带基本特征、形成演化与动力学特征进行论述的基础上,将与沂沭断裂带相匹配的一系列次级断裂构造统一划分为沂沭断裂带的羽状断裂系统。研究表明沂沭断裂带经历了大规模的左行平移、伸展、拉张及挤压作用,形成了以堑垒构造、盆岭构造、羽状构造系统及大陆边缘花岗岩系为特征的完整构造体系,与之同时伴生形成的胶东地区次级羽状构造系统,既是沂沭断裂带的次级断裂构造,又自成体系,是胶东地区的控矿容矿构造,它们的形成演化受沂沭断裂带的运动学特征和力学特征制约,整体上服从于沂沭断裂带的运动学机制,但又有各自的演化特征和力学特点,是胶东地区金矿形成的赋存场所。沂沭断裂带对胶东金矿的重要成矿贡献在于它不仅提供了幔源的物质来源     

东昆仑—北巴颜喀拉区域成矿规律及找矿工作思考

东昆仑地域依据地质构造差异所划分的昆北断褶带、昆中隆起带、昆南断褶带及其南邻的北巴颜喀拉褶皱带,在金—多金属成矿地质环境、矿床类型、控矿因素和分布规律上都各具特征,但其时空演化上具密切的内在联系,构成了极有远景的金属成矿省(带),是浅成热液金—多金属矿和砂金矿的远景区。     

Metallogenic origin of Sipingshan hot spring gold deposit in Hulin of Heilongjiang and its metallogenic mode

Sipingshan gold deposit is gold-bearing sillcalite in type. There only exist a few kinds of sulfide in the ore and it is lower in content. The gold degree is lower. Au is closely related to the Ag,Cu,Pb,As and Hg elements. The upper sillcalite has Eu and Ce negative anomaly,and the lower sillcalite has Eu positive anomaly. however,the hot spring cemented breccia and rhyolite porphyry have Eu negative anomaly;the S isotope component has deep-seated magmatic sulfur and terrestrial sulfate characteristic;and t...     

地幔橄榄岩中橄榄石的指示意义

橄榄石是地幔橄榄岩和辉石岩的主要组成矿物,但也经常以斑晶和捕虏晶的形式出现在玄武质岩石中。结合近年来在地幔橄榄岩的主要元素(如Mg和Fe)组成特征以及Li、Mg和Fe稳定同位素地球化学方面的研究成果,重点对橄榄石的地球化学特征与华北克拉通岩石圈地幔演化过程之间的联系进行了讨论,旨在加深对华北克拉通岩石圈地幔演化过程的理解。现有研究表明:地幔橄榄岩中橄榄石的矿物学特征、元素和同位素地球化学组成能够很好地指示岩石圈地幔的特征及其演化过程,因而具有重要的意义。对于克拉通地区的地幔橄榄岩来说,橄榄石的Mg#通常可以指示岩石圈地幔的属性,古老、难熔的地幔橄榄岩中的橄榄石一般具有较高的Mg#(>92),而新生的岩石圈地幔橄榄岩中的橄榄石则具有较低的Mg#(<91)。因此,地幔橄榄岩中橄榄石的Mg#在一定程度上具有年龄意义。橄榄岩中橄榄石的Li、Mg和Fe同位素组成也可以明确指示岩石圈地幔的属性及其所经历的演化过程,正常地幔的δ7Li、δ26Mg和δ57Fe组成相对均一,如果上述同位素组成偏离正常地幔值,则说明岩石圈地幔经历了熔体/流体的交代作用。华北克拉通地区地幔橄榄岩捕虏体中橄榄石的Li、Mg和Fe同位素组成研究表明:该区的岩石圈地幔经历了多个阶段、不同来源的熔体/流体的改造过程。     

秦岭泥盆系中铅锌矿床的热水沉积成因

秦岭泥盆纪铅锌成矿带提供了一种沉积岩中热水沉积矿床形成的典型构造背景,成矿作用发生在被动大陆边缘上的裂陷盆地中,与盆地造山前的发展和演化有关。同沉积期断裂控制着成矿洼地的发育,地热异常促使热水系统形成,已经识别出来若干古地热异常存在的标志。碰撞造山过程中盆地封闭,含矿沉积物受到不同程度的变形和变质改造。 可以把泥盆纪地层中的各种金属矿床纳入一个热水沉积成矿系列中,铅锌主要是在热水系统释放到海底时的沉积成岩过程中富集的,铜和金则表现有在热水系统晚期相中或后期改造中富集的趋势。