Gold Occurrence and Ore Genesis,Yata Micro—Disseminated Gold Deposit,Guizhou,Southwest China

The mode of occurrence of gold in the Yata micro-disseminated gold deposit is ap-proached through chemical phase studies coupled with ore-dressing monitoring and micro-beam analysis.The results showed that gold occurred for the most part as ultra-microscopic particles adsorbed on the surfaces or fracture planes of pyrite and other sulphides.The proportions of gold of different occurrences were estimated solutions containing nanometer-sized gold particles were prepared following the hydrolysis-reduction procedure and the adsorption of nanometer-sized gold on ordinary sulphides and rocks was experimentally determined.It is evident that sulphides are good adsorbents of gold and this is consistent with geological observations.     

Newly Discovered Scheelite in Quartz Vein-type Gold Deposits, Xiaoqinling Gold District, and its Geological Significance

正Objective The Xiaoqinling district is the second largest goldbearing province in China after the Jiaodong region located in the eastern North China Craton. At present, seven large, 20 medium-sized and 28 small gold deposits have been discovered, and more than 1200 gold-bearing quartz veins have been identified within the metamorphic rocks of the Taihua Group. The total gold reserves are over 800 tons. Our research comprises a systematic study     

Beiya Gold Deposit,Heqing County,Yunnan——One of China's Ten Biggest Gold Deposits

<正>The Beiya gold polymetallic ore district covers an area of 22.06 km2 and is located 47.5 km away in the direction 172°from Heqing county seat of northwestern Yunnan.Its geographical coordinates are 100°11′15″–100°13′00″E and6°07′30″–26°10′30″N.Since its discovery in 1999 until November 31st 2013,it has had accumulative proven(111b+122b+331+332+333)gold metal amounts of 258.475t at an average grade of 2.61 g/t.This deposit contains 88.98million tons of paragenetic and associated iron ores,with TFe grade varying from 9%to 36%;metal amounts are:gold     

Geochemical Styudy of Gold and Arsenic Mineralization of the Carlin-Type Gold Deposits,Qinling Region,China

Element geochemistry of gold arsenic and mineralogical features of their sulfides in the Carlin-type gold depostis of the Qinling region are discussed in this paper.The initial contents of ore-forming elements such as glod and arsenic are high the ore-bearing rock series in the Qinling region.Furthermore,both the metals are concentrated mainly in the diagenetic pyrite.Study on the mineralogy of arsenic-bearing sulfide minerals in the ores demonstrated that there is a poistive correlation between gold and arsenic in the sulfide minerals.Available evidence suggests that gold in the As-bearing sulfide minerals in likely to be presented as a charge species(Au ),and it is most possible for it to replace the exxcess arsenic at the site of iron and war probably deposited together with arsenic as solid in the sulfide minerals. Pyrite is composed of(Aux^3 ,Fe1-2^2 )([AsS]x^3-[S2]1-x^2-),and arenopyrite of (Aux^3 ,Fe1-x^3 )([AsS]x^3-[AsS2]1-x^3-).The occurrence of glod in the As-sulfied minerals from the Carlin-type gold depostis in the Qinling region has been confirmed by electron probe and transmission electron microscopic studies.The results show that gold was probably depostied together with arsenicas coupled solid solutions in sulfide minerals in the early stage of mineralization.Metallogenic chemical reactions concerning gold deposition in the Carlin-type As-rich gold deposits would involve oxidation of glod and concurrent reduction of arsenic.Later,the deposited gold as solid was remobilized and redistributed as exsolutions,as a result of increasing hydrothermal alteration and crystallization,and decreasing resistance to refractoriness of the host minerals.Gold occurs as sub-microscopic grains(ranging from 0.04tp 0.16μm in diameter)of native gold along micro factures in and crystalline grains of the sulfiedes.     

The Physico—Chemical Conditions for Mobilization of Gold in Mobin Gold Deposit,Southwest Hunan,China

Experiments on water-rock interaction were carried out on wall-rock samples fromtheMobin gold deposit,Southwest Hunan,China ,with the aim of determining the optimum physical and chemical conditions for the mobilization of gold in solution.Results indicate that gold is most easily mobilized from the wall rock-tuffaceous slate of the Mobin Deposit.Mobi-lization is optimized if fluids are neutral to slightly alkaline and contain both chlorine and sul-phur ions at the concentration and composition of about[0.25M(NH4)2 1M NaCl].The amount of gold leached from the tuffaceous slate increases with temperature although the effect decreases above about 200℃.     

Transport and Concentration of Gold in Metamorphic—hosted Reworked Gold Deposits,China

Calculations based on the available thermodynamic data of AuCl ₂ ⁻ and Au (HS) ₂ ⁻ indicate that AuCl ₂ ⁻ is responsible for the transport and enrichment of gold during the stage of pre-concentration in the source bed while Au (HS) ₂ ⁻ is the main gold species involved in the formation of gold deposits in response to hydrothermal reworking. Acid chloride solutions witha _Cl ⁻ > 10° and sulfur-rich solutions with a_Σs in excess of 10⁻² are held as important criteria for gold enrichment in the source bed and for the formation of gold deposits by subsequent hydrothermal event, respectively.     

A Giant Gold System, Geita Greenstone Belt, Tanzania

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Geochemical Characteristics of Jinwozi Gold Deposit,Xinjiang

The Jinwozi gold deposit consists of gold-bearing quartz veins in a biotite granodiorite of Hercynian age (zircon U-Pb age ≈ 335.7 Ma). Ore mineralogy is simple. In addition to native gold, there are only small amounts of sulfides, mainly pyrite and minor sphalerite, chalcopyrite and galena. δ³⁴S values average 6.69‰, and δ¹⁸O 13.99‰ Abundant CO₂ is contained in fluid inclusions from quartz. Homogenization temperatures of fluid inclusions are between 186 and 262 °C. REE distribution patterns indicate that the igneous mass may have been derived from a common initial material of calcareous-argillaceous sediments and alkali basalts as the country rocks. In other words, the Jinwozi granodiorite is of remelting origin from crustal material. Isotopic evidence of S, O and Pb shows that the ore-forming material is genetically related to magmatic hydrothermal activity.     

Genesis of the Xinzhuang Gold Deposit, Shangxi

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Geological Characteristics and Occurrence of Gold in the Xiling Gold Deposit,Jiaodong Peninsula北大核心CSCD

西岭金矿床是胶东金矿集区内近来新发现的超大型破碎蚀变岩型金矿床(475吨@4.56 g/t),位于著名的三山岛金矿床的东侧。本文在详实的野外地质观察的基础上,系统介绍了西岭金矿床的基础地质特征,并运用光学显微镜和扫描电镜观察,结合电子探针分析,系统研究了西岭金矿床金的赋存状态。西岭金矿床大量金矿物(银金矿和自然金)主要赋存在Ⅱ阶段石英-黄铁矿和Ⅲ阶段灰石英-多金属硫化物脉中。西岭金矿床金矿物主要有晶隙金、裂隙金和包体金三种赋存状态,以晶隙金为主。金的主要载体矿物为黄铁矿,次为石英、黄铜矿和方铅矿等。金矿物粒度大小包括粗粒金、中粒金、细粒金和微粒金,以细粒-微粒为主。金矿物形态有粒状、叶片状、线状、钩状、枝杈状和哑铃状等,以粒状为主。金矿物成分以Au和Ag为主,含微量的Cu、Cr、Fe、Ni、Te、S等元素。金成色为685~831,以银金矿为主,含少量自然金。综合地质和地球化学特征,西岭金矿床为蚀变岩型金矿床,是由早白垩世中温岩浆热液充填-交代形成。     

Characteristics and Metallogenic Evolution of Ailaoshan Gold Metallogenic Belts in Yunnan, China

CHARACTERISTICS AND METALLOGENIC EVOLUTION OF AILAOSHAN GOLD METALLOGENIC BELTS IN YUNNAN, CHINANNSFC(973Hi techProjects)andProjectofYunnanProvince ChineseAcademyofSciencescorporation(YK980 0 8 3)     

内蒙古额济纳旗疙瘩井金矿区构造-蚀变-地球化学综合方法找矿研究

北山中南带分布着众多受韧-脆性构造蚀变带控制的金矿床(点),此类矿化的显著特征是石英微细脉或构造蚀变岩含矿且富,而围岩几乎不含矿,短距离内金品位变化剧烈,传统方法很难发现微矿化线索。运用成矿构造学分析、构造蚀变带填图和构造地球化学测量对产于北山中南带东段的疙瘩井金矿区进行了综合方法找矿研究,取得以下认识:全区可划分为4个构造蚀变分区,北西西向主干断层上盘为有利控矿构造,其韧-脆性构造带内的构造突变或应力转换位置是矿体潜在地段。绢云母化、钠长石化是一种特征的蚀变找矿标志。构造地球化学测量显示,Au是该区最主要的成矿元素,各元素异常空间分布与划分的4个构造蚀变分区配套,其中成矿元素异常呈北西向带状分布在北西西向主干断层上盘-成矿热液蚀变带。成矿构造分析着眼于矿区构造格架和控矿构造,构造蚀变分析着眼于地质过程中矿物岩石发生的变化及找矿标志,构造地球化学分析着眼于地质过程中流体化学成分的变化和找矿对象,三者互为补充、相互印证,是成矿时间-物理-化学空间的直观反映。根据本次工作,认为在北山地区通过构造-蚀变-地球化学综合方法寻找金微矿化线索是行之有效的。     

新疆托里金矿带矿化蚀变体系及遥感混合蚀变信息分解-复合提取研究

文章以新疆西准噶尔托里金矿带为例,基于ETM数据源,在矿区矿化蚀变体系系统研究基础上,以典型岩、矿石地物波谱的差异性为依据,设计出适合本区的混合矿化蚀变信息分解-复合提取方法,通过混合蚀变信息分解、多变量蚀变信息增强、对增强图像(复合)合成3个工作环节,形成最终的蚀变信息提取图像.经对比后,有18处遥感异常为已知金矿的反映,有3处遥感异常已提供国土资源大调查使用.     

新疆托里金矿带矿化蚀变体系及遥感混合蚀变信息分解-复合提取研究

文章以新疆西准噶尔托里金矿带为例，基于ETM数据源，在矿区矿化蚀变体系系统研究基础上，以典型岩、矿石地物波谱的差异性为依据，设计出适合本区的混合矿化蚀变信息分解-复合提取方法，通过混合蚀变信息分解、多变量蚀变信息增强、对增强图像（复合）合成3个工作环节，形成最终的蚀变信息提取图像。经对比后，有18处遥感异常为已知金矿的反映，有3处遥感异常已提供国土资源大调查使用。     

辽宁大板金矿床地质特征及找矿前景

矿床位于辽西台陷北缘,受ＮＥ和ＥＷ向断裂控制,属著名的排山楼金矿外围。前寒武纪斜长角闪岩是主要矿源层。断裂构造为成矿提供空间。金矿化与蚀变带关系密切,蚀变越强金含量越高。属韧性剪切带型金矿,糜棱岩化、斜长角闪质岩石和构造交汇部位是寻找金矿的重要标志。与排山楼金矿对比表明该地区具有找矿前景。     

辽宁排山楼金矿围岩的岩石学特征

排山楼地区变质作用的主要因素为热量(约600℃)、化学活动流体和压力(地压应力和挤压应力).地壳震动是造成本区造山作用的原因.这种现象与板块构造理论相吻合.矿物分异作用序列为:首先,受火成侵入活动的影响,产生片麻岩、糜棱岩、花岗岩;然后,经历地压和挤压的作用;最后,发生各种类型蚀变作用,包括绢云母化、硅化、碳酸岩化、方解石化、绿泥石化、脱氧作用等.排山楼金矿成矿模式可概述如下:a)成矿作用为热液蚀变型,矿床赋存在太古宙变质岩大型韧性剪切带中;b)矿体产于裂隙中;c)矿体形态与岩脉和细脉形态一致;d)围岩经历了强烈的蚀变作用;e)黄铁矿是最重要的富金矿物,热液流体来源于侵入体,在流经破碎带和裂隙带后,在围岩中沉积黄铁矿.主要岩石类型有花岗岩、角闪岩、片岩、片麻岩和糜棱岩.区内广泛发育青盘岩化、泥化和绢云母化蚀变作用.主要蚀变矿物有石英、黄铁矿、白云母、绢云母、绿帘石、黑云母、微斜长石、方解石、角闪石、云母和锆石.矿体主要赋存在花岗岩和片麻岩中.主要蚀变作用为绢云母化、黑云母化、硅化和方解石化.蚀变过程中,铁氧化物(铁帽、云母)覆于贫硫酸盐矿石表面.蚀变类型有青盘岩化(黏土)、泥化和绢云母化.通常,氧化铁与黏土矿物的混合影响卫星影像中光谱的反射.利用遥感技术方法,适于这类矿床的进一步预测研究.     

加拿大拜韦尔特半岛金-铜矿集区成矿地质背景与矿床特征

拜韦尔特半岛矿产资源主要包括铜、金和石棉,区域地层和构造是控制矿床形成、发展和叠加改造的主要因素。这些矿产资源主要赋存在拜韦尔特海洋带达利吉带圣母玛利亚亚带的早奥陶世潜次火山岩中,包括起源于超俯冲作用带的蛇绿岩套和火山岩盖层。其蛇绿岩套超镁铁堆积岩的热液蚀变岩中产出石棉,火山成因的块状硫化物型(VMS型)铜±金矿产在基性和双峰式火山岩中,金矿产在基性和超基性的热液蚀变岩中。而蛇绿岩套火山岩盖层中则产出与条带状含铁建造(BIF)有关的后生金矿,石英脉型或相关的交代型矿床则大多赋存在蚀变和变形的基性岩中。拜韦尔特半岛的构造样式和几何结构非常复杂。     

Orogenic Gold Mineralization in the Qolqoleh Deposit, Northwestern Iran

The Qolqoleh gold deposit is located in the northwestern part of the Sanandai‐Sirjan Zone, northwest of Iran. Gold mineralization in the Qolqoleh deposit is almost entirely confined to a series of steeply dipping ductile–brittle shear zones generated during Late Cretaceous–Tertiary continental collision between the Afro‐Arabian and the Iranian microcontinent. The host rocks are Mesozoic volcano‐sedimentary sequences consisting of felsic to mafic metavolcanics, which are metamorphosed to greenschist facies, sericite and chlorite schists. The gold orebodies were found within strong ductile deformation to late brittle deformation. Ore‐controlling structure is NE–SW‐trending oblique thrust with vergence toward south ductile–brittle shear zone. The highly strained host rocks show a combination of mylonitic and cataclastic microstructures, including crystal–plastic deformation and grain size reduction by recrystalization of quartz and mica. The gold orebodies are composed of Au‐bearing highly deformed and altered mylonitic host rocks and cross‐cutting Au‐ and sulfide‐bearing quartz veins. Approximately half of the mineralization is in the form of dissemination in the mylonite and the remainder was clearly emplaced as a result of brittle deformation in quartz–sulfide microfractures, microveins and veins. Only low volumes of gold concentration was introduced during ductile deformation, whereas, during the evident brittle deformation phase, competence contrasts allowed fracturing to focus on the quartz–sericite domain boundaries of the mylonitic foliation, thus permitting the introduction of auriferous fluid to create disseminated and cross‐cutting Au‐quartz veins. According to mineral assemblages and alteration intensity, hydrothermal alteration could be divided into three zones: silicification and sulfidation zone (major ore body); sericite and carbonate alteration zone; and sericite–chlorite alteration zone that may be taken to imply wall‐rock interaction with near neutral fluids (pH 5–6). Silicified and sulfide alteration zone is observed in the inner parts of alteration zones. High gold grades belong to silicified highly deformed mylonitic and ultramylonitic domains and silicified sulfide‐bearing microveins. Based on paragenetic relationships, three main stages of mineralization are recognized in the Qolqoleh gold deposit. Stage I encompasses deposition of large volumes of milky quartz and pyrite. Stage II includes gray and buck quartz, pyrite and minor calcite, sphalerite, subordinate chalcopyrite and gold ores. Stage III consists of comb quartz and calcite, magnetite, sphalerite, chalcopyrite, arsenopyrite, pyrrhotite and gold ores. Studies on regional geology, ore geology and ore‐forming stages have proved that the Qolqoleh deposit was formed in the compression–extension stage during the Late Cretaceous–Tertiary continental collision in a ductile–brittle shear zone, and is characterized by orogenic gold deposits.     

金厂峪金矿床围岩蚀变特征与矿床成因

为了更深入地理解金厂峪金矿床成矿作用,对该金矿床内蚀变围岩的矿物组合、成分及其变化进行了较详细的研究.蚀变带质量平衡分析表明Al₂O₃、MnO、P₂O₅等组分具不活动性.由蚀变围岩向钠长石英脉,在蚀变岩中元素无明显变化.钠长石英脉体的形成与围岩蚀变有关,但两者成因并不相同.金厂峪金矿床的形成可能与深源流体有关     

内蒙红花沟金矿蚀变岩型金矿体控矿构造分析

红花沟金矿矿区内已发现40余条金矿脉和含金石英脉,它们均产于在区域Ⅰ级和Ⅱ级断裂构造(龙头山断裂)控制下侵位的燕山期龙头山花岗岩岩体与太古宙古老变质岩的内、外接触带上.蚀变岩型矿体是2000年发现和圈定出的新类型金矿体,分布在走向NW305 °的龙头山断裂的下盘,受其次级弧形构造所控制.分析认为沿龙头山断裂向上迁移的含金流体在运移到碎裂状糜棱岩化花岗岩后,在其中交代、充填并产生硅化、绢云母化和黄铁绢英岩化,形成蚀变岩型金矿体.晚阶段含金流体则在已蚀变的碎裂状花岗岩中充填成矿,进一步提高了蚀变岩型矿体和矿石的工业品位.