Assessing the Impact of Gold Mining on the Quality of Water Resources in the Commune of Meguet, Burkina Faso

Despite its often illegal nature, artisanal gold mining in Burkina Faso contributes to the economic and social development of the country. However, the rudimentary techniques used in gold panning have a significant impact on the environment due to inappropriate practices and the use of various chemical substances. This study aims to assess the impact of artisanal gold mining on the quality of water resources in a rural community at Méguet, Burkina Faso. To this end, surface and groundwater samples were collected and analyzed at the BUMIGEB laboratory. Field results show that the waters are slightly alkaline (6.97 < pH < 8.1), weakly mineralized and conductive (124 < EC < 543 μS/cm), with temperatures ranging from 24.6˚C to 31.6˚C. In addition, trace metals (TMEs) analyzed from surface and subsurface waters show very high levels, generally deviating from the levels recommended by WHO guidelines for Burkina Faso. Trace metals contamination of water resources in the commune of Méguet is mainly due to Fe (3.78 - 11.12 mg/kg), Hg (0.03 - 0.29 mg/kg), As (0.01- 6.31 mg/kg) and Pb (0.01 - 3.8 mg/kg). This study can serve as a basis for guiding national environmental policies to protect the water resources of the Méguet mine.

Trace element and REE geochemistry of the Zhewang gold deposit, southeastern Guizhou Province, China

The quartz vein-type gold deposits are widely hosted by the Neoproterozoic(Xiajiang Group) epimetamorphic clastic rock series in southeastern Guizhou Province, China. The Zhewang gold deposit studied in this paper occurs in the second lithological member of the Pinglue Formation of the Xiajiang Group. Trace element geochemistry of host rocks, quartz veins and arsenopyrite has revealed that ore-forming fluid was enriched in sulphophile elements such as Au, Ag, As, Sb, Pb and Zn, and simultaneously concentrated some magmaphile elements such as W and Mo, which probably provides some evidence for multi-stage mineralization or overprinting of magmatic hydrotherm. Quartz veins and arsenopyrite were characterized by depletion in HFSE and enrichment in LREE. Hf/Sm, Nb/La and Th/La imply that the ore-forming fluid was probably a NaCl-H2O solution system enriched in more Cl than F; Th/U values reflect the strong reducibility of the ore-forming fluid, coincident with the sulfide assemblages. The values of Co/Ni reflect that magmatic fluids may have partly participated in the ore-forming process and Y/Ho values have proved that the ore-forming fluid was associated with metamorphism and exotic hydrotherm which has reformed former quartz veins during late mineralization. The concentrations of REE, Eu anomalies and Ce anomalies of this deposit display that ore-forming elements mainly were derived from host rocks and possibly from a mixed deep source, and the ore-forming fluid was mixed by dominant metamorphic fluid and minor other sources. The physical-chemical conditions of ore-forming fluid changed from the initial stage to the late stage. The metamorphic fluid is responsible for the mineralization. Therefore, the Zhewang gold deposit is classified as a quartz vein-type gold deposit which may have been reformed by magmatic fluids during the late stage.

Determination of Trace Elements in High Purity Gold by High Resolution Inductively Coupled Plasma Mass Spectrometry

Trace elements were determined in high purity gold by high resolution inductively coupled plasma mass spectrometry （HR-ICP-MS）. Sample were decomposed by aqua regia. To overcome some potentially problematic spectra/ interference, measurements were acquired in both medium and high resolution modes. The matrix effects due to the presence of excessive HCl and Au were evaluated. The optimum conditions for the determination was tested and discussed. The standard addition method was employed for quantitative analysis. The detection limits range from 0.01ug/g to 0.28ug/g depending on the elements. The method is accurate, quick and convenient. It has been applied to the determination of trace elements in high purity gold with satisfactory results.

The Application of Scanning Proton Microprobe (SPMP) in Study of Trace Gold Distribution

Studies on distribution of trace gold mostly focus on some samples in whichgold content is well above 100 ppm at the present time due to the limitation of analy-sis methods. Progress in research on trace gold (usually less than 100 ppm to n ppm)was rarely reported. Although electronic microprobe (EMP) and scanning electronicmicroprobe (SEM) have a high resolution, their detection limits are still 100-500ppm and 100-300 ppm, respectively. And also the electronic paramagnetic reso-nance spectrometer, an effective method for determining lattice gold of a few tenppm level, unfortunately is still incapable of doing such research. Newly

Characterization of Galena and Vein Paragenesis in the Penjom Gold Mine,Malaysia:Trace Elements,Lead Isotope Study and Relationship to Gold Mineralization Episodes

The Penjom Gold Mine is located 30 km from the Bentong-Raub Suture at the western boundary of the Central Belt in Peninsular Malaysia. Gold mineralization hosted within the vein system is associated with pyrite, arsenopyrite, and minor base metals including galena. Trace element and lead isotope analysis was undertaken on nine samples that represent two stages of galena formed during two tectonic events. Both the Pb isotopes and the trace elements show that the first stage galena within the mineralized areas at the footwall has different geochemical characteristics compared with galena in non mineralized areas in the hanging wall, suggesting that galena crystallized from two different ore fluids and probably at two different times. Higher Te, Se and Bi in the galena from the mineralized area may indicate hydrothermal fluids that migrate through the structural conduit and leached out the metal along the pathway that consist of dominant carbonaceous unit. The Pb isotopic ratio composition are transitional between the bulk crustal growth and an upper crustal growth curve, indicating that derivation was from arc rocks associated with continental crust or a crustal source that includes arc volcanic and old continental sedimentary rocks.

Trace element and REE geochemistry of Sanshenjiang gold deposit, southeastern Guizhou Province, China

The Sanshenjiang gold deposit in southeastern Guizhou Province, China, is hosted by the Neoproterozoic metasedimentary rocks which experienced low-grade greenschist facies metamorphism. Gold mineralization occurs mainly in the ribbon chiltern slate of the first member of the Longli Formation and is controlled by both strata and faults. Ore bodies are characterized by abundant quartz-arsenopyrite-gold-pyrite-bedding veins, veinlets and small lenses within the shear zone. In this study, trace element and REE geochemistry was analyzed to constrain the origin and genesis of this deposit. The trace element signatures of wall rocks and veins display a basically similar tendency in the spider diagram, showing the genetic relationship. The values of Co/Ni, Y/Ho, Hf/Sm, Nb/La and Th/La reflect that the hydrothermal fluids of this deposit were derived from the mixture of multiple sources with marked enrichment of Cl and moderate to high temperature. There is a broad similarity in the chondrite-normalized patterns and REE fractionation between wall rocks and ore bodies, possibly reflecting their similar origin. Based on the difference in δCe and δEu, quartz veins and lenses can be subdivided into weakly negative Ce-anomalies (δCe=0.81 to 1.06) with slight Eu anomalies (δEu=0.81 to 1.06) type and the significant positive Ce-anomalies (δCe=1.13 to 1.97) with moderate negative Eu-anomalies type, probably suggesting physical-chemical changes in the evolution process of ore-forming fluids from the early to late stage. It can be concluded that the ore-forming process may have experienced three stages: formation of the original ore source bed, regional metamorphism and gold mineralization, on the basis of trace element and REE analysis and field observation.

Rare Earth Element and Trace Element Features of Gold-bearing Pyrite in the Jinshan Gold Deposit,Jiangxi Province

Jinshan gold deposit is located in northeastern Jiangxi,South China,which is related to the ductile shear zone.It has a gold reserve of more than 200 tons,with 80%of gold occurring in pyrite. The LREE of gold-bearing pyrite is as higher as 171.664 ppm on average,with relatively higher light rare earth elements（LREE;159.556 ppm） and lower HREE（12.108 ppm）.TheΣLREE/ΣHREE ratio is 12.612 and（La/Yb）_N is 11.765.These indicate that pyrite is rich in LREE.The（La/Sm）_N ratio is 3.758 and that of（Gd/Yb）_N is 1.695.These are obvious LREE fractionations.The rare earth element（REE） distribution patterns show obvious Eu anomaly with averageδEu values of 0.664,andδCe anomalies of 1.044.REE characteristics are similar to those of wall rocks（regional metamorphic rocks）,but different from those of the Dexing granodiorite porphyry and Damaoshan biotite granite.These features indicate that the ore-forming materials in the Jinshan gold deposit derived from the wall rocks, and the ore-forming fluids derived from metamorphic water.The Co/Ni ratio（average value 0.38） of pyrite suggests that the Jinshan gold deposit formed under a medium-low temperature.It is inferred from the values of high-field strength elements,LREE,Hf/Sm,Nb/La,and Th/La of the pyrite that the ore-forming fluids of the Jinshan gold deposit derived from metamorphic water with Cl〉F.

Trace Elements in Fluid Inclusions in the Carlin-Type Gold Deposits, Southwestern Guizhou Province

Fluid inclusions in quartz from the Lannigou and Yata Carlin\|type gold deposits in southwestern Guizhou were analyzed by inductively coupled plasma\|mass spectrometry for their trace elements (Co, Ni, Cu, Pb, Zn, Pt, etc.). The results show that quartz fluid inclusions entrapped at different ore\|forming stages contain higher Co, Ni, Cu, Pb and Zn. It has been found for the first time that the ore\|forming fluids responsible for the Carlin\|type gold deposits are rich in Pt. From this it can be concluded that basic volcanic rocks seem to be one of the important sources of ore\|forming materials for the Carlin\|type gold deposits.

右江盆地金、锑成矿过程:来自晴隆锑矿床和泥堡金矿床萤石LA-ICP-MS微量元素研究的制约

位于“滇-黔-桂”接壤处的右江盆地中发育大量的金、锑矿床,金、锑相互伴生,具共生分异特征。然而,金、锑之间的成矿联系和成矿过程异同仍需要进一步的研究工作。萤石作为热液矿床中广泛出现的脉石矿物,前人已经对其开展了大量的研究用于揭示矿床的形成过程。右江盆地中的晴隆锑矿床和泥堡金矿床具有相似的成矿时代以及围岩蚀变特征,是研究金、锑共生分异的理想对象。因此,本文选择晴隆锑矿床和泥堡金矿床中与成矿相关的萤石展开原位LA-ICP-MS微量元素研究,旨在揭示金、锑矿床成矿过程的差异。萤石矿物化学及阴极发光(CL)研究显示,晴隆锑矿床中与成矿相关的萤石沉淀可以划分为三个阶段,第一阶段稀土元素呈LREE富集HREE亏损的右倾特征,第二阶段呈“中稀土(MREE)”富集,第三阶段沉淀的萤石基本继承了第二阶段的稀土元素的配分特征,但ΣREE更低。整体上,随着成矿过程进行,三个阶段萤石ΣREE随着成矿过程逐渐下降,且均伴随Ce的负异常。泥堡金矿床中与成矿相关的萤石沉淀可以划分为两个阶段,第一阶段萤石稀土元素也呈右倾特征,第二阶段萤石呈MREE富集特征,整体上与晴隆萤石大致相似。不同阶段萤石Y/Ho、La/Ho、Tb/Ca和Tb/La图解显示,锑、金矿床中成矿早阶段和晚阶段萤石具有不同成因特征。其中,成矿早阶段萤石主要为热液充填成因,成矿晚阶段与水/岩反应密切相关,随着水/岩反应加剧,大量围岩组分进入流体形成晚阶段萤石。同时,这一过程导致成矿流体pH的逐渐升高和稀土元素总量的逐渐降低。综合分析认为,锑成矿流体为酸性流体,强烈的水/岩反应促使碳酸盐岩围岩溶解形成大量的萤石;同时成矿环境p H的增高和成矿流体温度的降低可能是导致辉锑矿大量沉淀的原因之一;而金成矿流体呈弱酸-中性特征,去碳酸岩化作用不彻底,形成少量萤石并伴生大量白云石,有利于大量含金黄铁矿的形成。通过对已有的锑矿床中辉锑矿及成矿阶段脉石矿物稀土元素研究数据统计发现,成矿阶段脉石矿物稀土元素呈MREE富集特征可能是大量辉锑矿对轻稀土元素(La)的富集作用所导致的。

滇东南茶花寨金矿床载金黄铁矿LA-ICPMS原位微量元素组成与地质意义

右江盆地是世界上卡林型金矿床最集中的地区之一,盆地南缘的滇东南地区是其重要组成部分。茶花寨金矿床为滇东南地区产于印支运动不整合面附近的代表性金矿床,黄铁矿为主要的载金矿物,其环带特征明显,为认识该区卡林型金矿成矿作用提供了理想的实例。本文在野外考察及镜下观察的基础上,通过LA-ICPMS分析技术,对茶花寨金矿床中不同期次黄铁矿开展了原位微量元素组成分析,以总结不同成矿阶段金的富集特征与关键控制因素。研究结果表明,该矿床黄铁矿存在3个期次:沉积成因的Py1,包括草莓状黄铁矿Py1a和环带状黄铁矿核部Py1b,交代成因的中间环带Py2,热液成因最外侧环带Py3。其中,Py1b富集Sb、Pb、Zn等元素,Py2富集As、Co、Ni,Py3则具有较高的Au、As、Cu、Sb含量和稍高的Se、Hg、Tl含量。三者对比显示,Py2中As含量最高,Py1b和Py2除As以外的其他微量元素含量接近或Py2中含量稍低,二者Co/Ni比值均在0.1附近,表明Py2为Py1b受热液交代改造形成;而Py3中微量元素组成与Py1b和Py2差异明显,指示其热液成因,且Py3中Co、Ni含量相较Py1b和Py2更低,Co/Ni比值在0.01~0.1之间,表明成矿流体温度较低且不富集Co、Ni,Py3中Co、Ni主要继承自Py1b和Py2。该矿床Au主要以晶格金的形式赋存在Py3中,其进入黄铁矿晶格与As、Sb、Cu、Se等元素相关。综上所述,茶花寨金矿床成矿流体为富集Au、As、Cu、Sb、Se、Tl等元素的低温热液流体,在到达赋矿地层后,交代Py1b形成高砷的中间环带Py2,流体中Au受高砷的Py2吸附聚集,在Py3形成过程中沉淀下来,最终以固溶体的形式赋存其中。

四川康定偏岩子造山型金矿床成因:石英微量元素和硫化物S同位素证据

大渡河金矿带是中国重要的金矿化富集区,发育一系列造山型金矿床。偏岩子金矿床位于大渡河南段的康定地区,矿体赋存于震旦系灯影组白云岩中。金成矿过程分为金-黄铁矿-石英阶段、金-氟镁石阶段、金-硫化物-氟镁石-石英阶段和黄铁矿-白云石-白云母阶段4个成矿阶段。通过石英中微量元素和硫化物S同位素的原位分析,旨在约束成矿流体性质、成矿物质来源和矿床成因。石英中Li,B,Na,Al,P和K相对富集,主要以Al^(3+)^(+)(Li^(+),Na^(+),K^(+),H^(+))Si^(4+)和Al^(3+)^(+)P 5^(+)2Si^(4+)的替换机制进入石英晶格。石英中Al与Li呈明显正相关关系,指示其形成温度较低。围岩中硫化物的δ^(34) S值介于-22.3‰~-13.1‰之间,表明S来源于海相硫酸盐的细菌还原作用;矿石中硫化物的δ^(34) S值范围为5.4‰~7.0‰,与交代岩石圈地幔的硫同位素值一致。综合矿床地质特征、石英微量元素和硫化物硫同位素组成,研究认为偏岩子属于造山型金矿床。成矿流体在上升过程中与赋矿白云岩接触,发生水-岩反应,导致自然金、含金硫化物、氟镁石和萤石的沉淀结晶。

氯化物体系中微量金的协同萃取分离研究

研究了用DIBK(二异丁基酮,HA)和TBP(磷酸三丁酯,B)协同萃取体系分离和富集氯化物体系中的金,考察了萃取体系及组成、萃取时间和温度、水相中氯离子浓度、萃取相比(V_(O)/V_(A))对金萃取分离性能的影响,并采用斜率法初步探究萃取机制。结果表明:在协同萃取体系为TBP-DIBK、萃取剂总浓度1.5 mol/L、n(TBP)∶n(DIBK)=1∶4、萃取时间20 min、萃取温度20℃、V_(O)/V_(A)=2/1、水相中氯离子浓度6 mol/L条件下,金萃取率可达98.82%,最大金/铜萃取分离系数为1189.05;斜率法研究表明,萃合物组成可能为[AuCl_(6)·3A·B],其萃取化学反应式可改写为Au^(3+)+6Cl^(-)+3HA+B→[AuCl_(6)·3A·B]+3H^(+)。

镇旬盆地南缘淋湘金矿床地质特征及矿床成因探讨

淋湘金矿床是南秦岭镇安-旬阳盆地南缘一处典型的微细浸染型金矿床,矿体受近EW向断裂控制,赋矿围岩为下泥盆统西岔河组斑点状千枚岩和中泥盆统杨岭沟组灰岩夹千枚岩。由于对该矿床成矿物质来源的认识存在不同观点,致使对该矿床的成因存在热水沉积成因、喷流沉积-后期热液叠加改造等多种观点,难以建立统一的成矿模式。本文以淋湘金矿床的黄铁矿和自然金为研究对象,对其开展电子探针、LA-ICP-MS原位微区硫同位素和微量元素分析,探讨金的赋存状态,限定成矿物质来源与矿床成因。研究结果表明,淋湘金矿床的金以裂隙金和包体金为主,少数以显微纳米金(Au 0)形式赋存于黄铁矿晶格中。Ⅱ成矿阶段硫同位素在16.28‰~17.84‰之间,平均值为16.91‰;Ⅲ成矿阶段硫同位素在15.19‰~15.68‰之间,平均值为15.51‰。这一特征与金龙山卡林型金矿床相似,成矿阶段具有地层硫特征,后期有岩浆硫的混入。从PyⅡ-Ⅲ阶段,Au、Ag、Cu、Pb、Zn、Pb、Bi等成矿元素均呈增加趋势,As元素含量呈下降趋势,Co、Ni元素含量略有上升。PyII的Co/Ni比值差异较大,可能与黄铁矿后期变质重结晶有关;PyIII大部分Co/Ni比值大于1.00,表明其为热液成因黄铁矿。不同元素之间相关性具有较大差异,成矿流体为混合源,推测在主成矿阶段晚期可能遭受岩浆热液事件扰动。主成矿阶段流体包裹体气相成分中CO_(2)等挥发分的逸失及CH_(4)的加入,表明流体发生了不混溶作用。综上所述,淋湘金矿床成因过程可总结为:随着大气降水和变质流体沿构造裂隙向上运移,该混合流体萃取地层中成矿物质,并在成矿有利部位因为流体不混溶作用导致成矿物质沉淀析出,而后期岩浆热液的加入使成矿物质进一步富集。

西秦岭加甘滩金矿成因研究:毒砂Re-Os定年、载金矿物原位微量元素和硫同位素限定

西秦岭加甘滩金矿是夏河-合作地区最大的金矿,但其矿床成因存在争议,其中主要问题在于该矿床成矿时代缺乏研究。通过野外工作和镜下观察,识别出两种毒砂和黄铁矿:毒砂Apy1(较为常见,在矿石中呈浸染状产出)和毒砂Apy2(数量较少,围绕黄铁矿Py1产出),黄铁矿Py1(浸染状黄铁矿)和黄铁矿Py2(黄铁矿脉)。本次工作对毒砂进行Re-Os定年,以期确定加甘滩金矿的成矿时代:通过对Apy1进行了Re-Os定年,获得毒砂的Re-Os等时线年龄243.1±8.7Ma,该年龄与夏河-合作区域岩浆作用(232~249Ma)相对应。利用LA-ICP-MS和LA-MC-ICP-MS对成矿期毒砂和黄铁矿进行了微量元素和硫同位素测定。微量元素测试结果显示加甘滩金矿硫化物内的不可见金以固溶体形式赋存,Apy2的不可见金含量最高可达521×10^(-6),其他毒砂和黄铁矿不可见金含量最高为119×10^(-6)。加甘滩金矿的平均品位为2~3g/t,依据质量平衡计算,如果毒砂和黄铁矿内不可见金发生再活化,不可见金含量需要达到20~30g/t,但实际金含量远低于所需,需要额外的岩浆热液来源。Py1、Py2、Apy1和Apy2的原位硫同位素结果分别为-14.3‰~-7.70‰(平均-10.0‰)、-14.5‰~-9.60‰(平均-12.5‰)、-13.0‰~-6.40‰(平均-8.54‰),-11.2‰~-9.00‰(平均-10.1‰),反映其硫同位素发生了分馏。将加甘滩金矿成矿期硫化物的硫同位素与成岩期和典型岩浆热液型黄铁矿硫同位素进行对此,指示其成矿流体为岩浆热液来源。综上,本文研究指示加甘滩金矿属于岩浆热液成因。

上黑龙江盆地砂宝斯金矿黄铁矿地球化学特征及其成矿意义

砂宝斯金矿床是上黑龙江盆地内唯一的大型岩金矿床,但其成矿物质来源和矿床成因仍然存在争议。为此,在详细的矿相学和黄铁矿显微结构研究基础上,对不同世代黄铁矿开展LA-ICP-MS微量元素和S、Pb同位素分析。结果表明,砂宝斯金矿床从成矿早期到主成矿阶段,黄铁矿可划分为3个世代,不同世代黄铁矿微量元素组成差异明显。PyⅠI为金的主成矿期,其中Au、Ag、Cu、Pb、Zn、Bi、Co、Ni、As、Mn、Sb、Sn、Ga等元素含量较高。Co、Ni、As以类质同象的形式进入黄铁矿晶格, Cu、Pb、Zn、Sb、Bi元素以金属硫化物矿物包裹体的形式赋存于黄铁矿中。Au元素以Au^(+)、银金矿、铜金矿矿物包裹体微粒和亚微米的包体金形式存在于黄铁矿中。As–置换S–,形成Au(HAs)–,对Au的迁移及沉淀具有重要的作用。砂宝斯金矿床黄铁矿Co/Ni比值大多数小于1,大部分点落入沉积成因范围,少部分落入火山成因和热液成因范围,表明黄铁矿并非单一来源。综合S、Pb同位素及黄铁矿微量元素特征,砂宝斯金矿床成矿物质既来源于具上地壳和地幔混源特征的深部岩浆,又来源于二十二站组围岩。结合区域成矿构造背景,认为蒙古—鄂霍茨克洋闭合后,早白垩世陆壳拆沉引发岩浆作用形成的初始成矿流体形成PyⅠ型黄铁矿,Cu、Pb、Zn、Ag、Au、Bi含量较少,Co、Ni含量相对较高;由于大气降水的加入,成矿流体运移过程中萃取二十二站组围岩中成矿物质,富含As、Cu、Pb、Bi、Au、Ag,形成沉积成因的PyⅡ型黄铁矿;成矿晚期由于大气降水的减少,形成既有沉积成因又有热液成因的PyⅢ型黄铁矿。砂宝斯金矿床成因类型为岩浆热液型金矿床。

化探样品中石墨炉痕量金测定技术研究

为实现对化探样品中石墨炉痕量金的测定,本文开展了对其测定技术的相关研究。本研究实验分析方法在Fe3+存在条件下,在质量分数为10%的王水中,利用泡沫塑料吸附金;在质量分数为1.2%的硫脲溶液中解析;采用最大功率升温和石墨炉原子吸收光谱测定方法。通过对测定结果进行分析可以得出,该分析方法检出限低,测定结果的精密度和准确度均能够满足国家一级标准物质分析验证要求,确保测定结果与真实标准值相符合。

藏南中成明赛和浅成马扎拉金矿床成矿异同:来自地质和硫化物原位微量元素、硫同位素约束

特提斯喜马拉雅带地处青藏高原南部,是产于青藏高原大陆碰撞背景的新生代金成矿省,然而其赋存的造山型金矿床分布零散,且不同构造层次造山型金矿床(如中成、浅成)的蚀变矿化、流体组成和成矿过程缺乏系统对比。本文通过详细对比特提斯喜马拉雅东段中成明赛金矿和浅成马扎拉金(锑)矿床蚀变矿化、硫化物结构、原位微量元素和硫同位素组成,探讨其成矿过程、成矿流体组成及控制因素。两矿床均赋存于侏罗系板岩和凝灰岩夹层中,板岩中蚀变弱,沿层理发育浸染状黄铁矿-铁白云石-绢云母-石英;而凝灰岩夹层蚀变强,长石和黑云母等矿物已蚀变为铁白云石、绿泥石和绢云母等,并发育大量浸染状自形-半自形黄铁矿和毒砂。板岩中黄铁矿(明赛:Py sa;马扎拉:Py sb)结构均较为均一,且Au(平均为0.33×10^(-6))等微量元素含量低,δ^(34)S值变化较大(Py sa:8.12‰~15.6‰;Py sb:-24.3‰~3.36‰)且与侏罗系地层δ^(34)S值相吻合。明赛凝灰岩中黄铁矿(Py va)发育富砷同心环带,具较高的Au(平均含量为14.3×10-6)、As含量,而马扎拉凝灰岩中黄铁矿(Py vb)发育不规则核-边结构且富Au(平均含量为3.8×10-6)、Cu、Pb、Sb。两矿床凝灰岩中黄铁矿和毒砂的δ^(34)S值相似(Py va平均值为2.7‰、毒砂为2.4‰;Py vb平均值为3.2‰、毒砂为3.2‰),与藏南造山型金矿中黄铁矿δ^(34)S值一致。上述两个矿床板岩中黄铁矿贫金且硫同位素组成差异较大,可能为成矿流体与含不同沉积黄铁矿围岩反应所致;而凝灰岩中的黄铁矿富金且与毒砂具有相似的硫同位素组成,可归因于同源流体与相同围岩发生均一化水岩反应。本次研究表明藏南地区广泛分布的凝灰岩是形成造山型金矿的有利岩性,研究区不同构造层次的造山型金矿具相似物质源区,成矿系统差异性受控于不同水岩反应过程。

东昆仑驼路沟钴金矿床中黄铁矿的结构和成分特征及其对钴成矿作用的启示

驼路沟钴金矿床是我国少见的大型热液型矿床。为了深入认识该矿床(含)钴成矿过程,选取驼路沟矿床中的富钴黄铁矿为研究对象,通过岩相学、矿物学、微量元素特征和S同位素组成分析,确定黄铁矿结构、成矿流体特征、演化过程及成矿物质来源,进而揭示详细的成矿过程,以及黄铁矿对钴成矿的指示作用。研究表明,驼路沟含钴黄铁矿可分成三部分:晶型较好、偶见孔隙的黄铁矿核部;具有震荡环带,与硫镍钴矿、辉砷镍矿共生的黄铁矿幔部;晶型较好的黄铁矿边部。其中,黄铁矿核部富集Co、Ni等元素,幔部富集Co、Ni、As等元素,边部具有较高的As、Se含量和稍高的Au含量。三者对比显示,核部Co含量最高,幔部As含量最高,边部含有较高的Au,三者ω(Co)/ω(Ni)值绝大部分都大于1,指示其热液成因;从核部到幔部再到边部,Co、Ni含量逐渐降低,Se含量逐渐升高,说明其流体温度逐渐降低;黄铁矿中δ^(34)S值整体为-1.43‰~0.48‰,说明成矿物质主要来源于岩浆。黄铁矿的结构、微量元素特征、S同位素组成表明,驼路沟的成矿流体为富含Co、Ni、As等元素的低温热液流体。本研究对于揭示喷流热液型钴矿床成矿过程及指导类似矿床的找矿勘查具有重大意义。

复古金饰品中金及微量元素的检测研究

复古金饰品是一种新型足金饰品,作为一种新产品,因其款式多样,硬度较高,可以满足人们的特色需求。为研究这种产品,实验中采用X射线荧光光谱法、ICP光谱法、火试金法、硬度仪对黄金样品进行了测试和研究。研究结果表明:复古金饰品因加工特性和杂质元素种类较多,又缺少合适的标准物质,X射线荧光光谱法分析结果不理想,可选用ICP光谱法和火试金法进行检测。硬度测试结果显示,复古金饰品硬度远高于普通足金。

Isotope Tracing and Prospecting Assessment of Gold-Silver Deposits in Zhejiang Province

Three different types of gold and silver deposits in Zhejiang Province(Huangshan gold deposit, Zhilingtou gold-silver deposit and Haoshi silver deposit) showmarked differences in lead and strontium isotopic composition, suggesting three differentsources and geneses of these deposits. The Huangshan gold deposit features low initial Srisotope ratios and low μ values or low content of radiogenic Pb and its ore-forming materialscame primarily from the upper mantle; the Zhilingtou gold-silver deposit shows high initial Srisotope ratios and high μ values or high content of radiogenic Pb and the ore-forming materialswere derived mainly from the upper crust; and the Haoshi silver deposit has its Pb and Srisotope ratios between the above two cases with the ore-forming materials stemming from boththe mantle and the crust. The characteristic Pb isotopic composition may serve as an indicatorfor prospecting for different types of ore deposits.