树脂分离富集质谱法测定矿石中痕量铂、钯、金

讨论了王水溶矿、树脂分离富集、在硝酸介质中用质谱法测定铂、钯、金。     

Migration behavior of platinum group elements in natural and technogeneous systems

Data were summarized on the speciation of the main platinum group elements (PGE) platinum, palladium, and rhodium in aqueous media, forms of their input into the environment, and mechanisms of accumulation by natural sorptive phases. In some cases, the results obtained for PGE were compared with those for gold. Data on PGE speciation in a number of natural environments were analyzed. It was found that the main factor controlling the migration ability of PGE (Pd > Pt»Rh) is the formation of stable compounds with dissolved organic matter, hydroxyl, and thiosulfate ions and nanometer-sized particles. The transport of dissolved PGE species by marine, riverine, and technogeneous suspended materials was evaluated as an alternative way of an increase in PGE mobility. Significant differences were revealed in the migration behavior of platinum, palladium, and rhodium indicating the dominance of palladium dissipation in a dissolved state. The possibility of the prediction of PGE accumulation and dissipation in technogeneous systems was demonstrated.     

The calculated solubility of platinum and gold in oxygen-saturated fluids and the genesis of platinum-palladium and gold mineralization in the unconformity-related uranium deposits

Thermodynamic calculations on the solubility of platinum and gold indicate that saline (1 m NaCl), fluids saturated with atmospheric oxygen can transport geologically realistic concentrations of platinum-group-elements (PGE), gold, and uranium as chloro-complexes. A number of calculations involving fluid-rock interaction suggest that the oxygen-saturated fluids flowing through rocks containing quartz, muscovite, kaolinite, magnetite and hematite, initially oxidize any magnetite to hematite, allowing subsequent batches of ore fluids to retain their high oxidation state. During their migration through the aquifer, the oxidizing fluids would move the oxidation-reduction interface deeper into the aquifer, leaching and redepositing platinum and gold. The redissolution of earlier precipitated platinum and gold depends on the fluid/ rock ratio and the associated increase in the oxidation state. Therefore, lowering of fluid/rock ratios and/or mixing of the oxidized fluids with a large amount of reduced fluid will precipitate uranium, PGE, and gold. It is suggested that this model can explain the genesis of gold and PGE mineralization in the unconformity-related uranium deposits of the Alligator Rivers Uranium Field in the Northern Territory, Australia.     

Iridium enrichment and poor fractionation from gold, platinum and palladium in clausthalite (PbSe), Tilkerode, eastern Harz, Germany

Enrichments in platinum-group elements were found in clausthalite, PbSe, which occurs in carbonate–hematite veins hosted in black shale of Upper Wenlockian age in the eastern Harz, Germany. Spot measurements by laser ablation–quadrupole inductively coupled plasma mass spectrometry (LA–QICPMS) show that the clausthalite has Pt contents that average 0.459?ppm and range from 0.003 to 2.83?ppm. Other noble metals quantified in the present work include Au (0.226?ppm, 0.109–0.451?ppm), Ru (0.061?ppm, 0.006–0.264?ppm), Ir (0.071?ppm, 0.010–0.185?ppm), Pd (0.046?ppm, 0.017–0.107?ppm) and Os (0.010?ppm, <0.003–0.024?ppm). Elemental ratios of Au/Ir, Pd/Ir and Pt/Ir, the average values of which are respectively 4.6, 0.8, and 4.9, suggest that Au, Pd and Pt are poorly fractionated from Ir. The resulting Ir enrichment is unusual and should reflect a particularly soluble (and stable) aqueous complex of Ir in a highly oxidizing, low-temperature, Se-rich solution.     

First finds of native palladium,platinum, gold,and silver in brown coals of the Erkovets field (upper Amur region)

Minerals of native elements (Pd, Pt, Au, Ag, and Au-Ag solid solutions) as well as Pb, Zn, Cu, Bi, Fe, Cr, Ni, W, Al, and their intermetallides, and a number of other ore minerals were discovered in brown coals of the Erkovets field. The structural reorganization of the noble metal grains and most of the other minerals found in the brown coals suggest their authigenic paragenesis. The input of noble metals in brown coals is possible in an ionic mode from the surface and underground waters as mineral particles transported by wind from goldfields.     

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.     

Occurrence of platinum,palladium and gold in pine needles of Pinus pinea L. from the city of Palermo (Italy)

Preliminary data on the presence of Pt, Pd and Au in airborne particulate matter from the urban area of Palermo (Sicily, Italy) are presented. They were obtained by analysing 40 samples of pine needles (Pinus pinea L.) collected in and around the city. Observed concentrations range from 1 to 102 μg/kg for Pt, 1 to 45 μg/kg for Pd and 22 to 776 μg/kg for Au. Platinum and Pd concentrations in pine needles are up to two orders of magnitude higher than their crustal abundances. They exhibit a high statistical correlation (R²=0.74) which suggests a common origin. Precious metal concentrations measured within the city centre are much higher than those occurring outside the town. The distribution patterns of Pt and Pd in the study area are compared to the distributions of Au and Pb. Gold is enriched at the same sites where Pt and Pd are enriched, while Pb shows some discrepancies. The most probable local source of all of these elements is traffic. Average Pt and Pd emissions in the city area are estimated to be about 136 and 273 g/a, respectively. This study supports the use of pine needles as biomonitors of PGE in the environment.     

Anomalous gold, antimony, arsenic, and tungsten in ground water and alluvium around disseminated gold deposits along the Getchell Trend, Humboldt County, Nevada

Ground-water, alluvium, and bedrock samples were collected from drill holes near the Chimney Creek, Preble, Summer Camp, and Rabbit Creek disseminated gold deposits in northern Nevada to determine if Au and ore-related metals, such as As, Sb, and W, are being hydromorphically mobilized from buried mineralized rock, and, if they are, to determine whether the metal-enriched ground water is reacting with the alluvial material to produce a geochemical anomaly within the overburden.Results of chemical analyses of drill-hole water samples show the presence of hydromorphic dispersion anomalies of Au, As, Sb, and W in the local ground-water systems associated with these deposits. Background concentrations for Au in the ground water up-gradient from the buried deposits was less than 1 nanogram per liter (ng/L), near the deposits the Au values ranged from 1 to 140 ng/ L, and in drill holes penetrating mineralized rock, concentrations of Au in the ground water were as high as 4700 ng/L. Highest concentrations of Au were found in ground-water samples where the measured E_h and the distribution of arsenic species, arsenite [As(III)] and arsenate [As(V)], indicated oxidizing redox potentials. Similarly, As, Sb, and W concentrations in the ground water near the deposits were significantly enriched relative to concentrations in the ground water up-gradient from the deposits. In general, however, the highest concentrations of As, Sb, and W occurred in ground-water samples where the measured E_h and the distribution of arsenic species indicated reducing conditions. Arsenic concentrations ranged from 9 to 710 micrograms per liter (μg/L); Sb, from less than 0.1 to 250 μg/L; and W, from 1 to 260 μg/L.In addition, analysis of sequential dissolution and extraction solutions of drill cuttings of alluvium and bedrock indicate geochemical anomalies of gold and ore-related metals in the overburden at depths corresponding to the location of the present-day water table. This relationship suggests that water-rock reactions around these buried deposits are active and that this information could be very useful in exploration programs for concealed disseminated gold deposits.     

内蒙古虎拉林地区砂金与岩金的关系

虎拉林地区砂、岩金矿的空间位置关系十分密切。在虎拉林河上中下游及虎拉林岩金矿分别采取样品，结果表明虎拉林河砂金粒度大，分选较差，磨圆度差；砂金形态总体上以粒状为主；溶蚀系数均值小于1。微量元素含量特征表明砂金的主要物质来源是近源，与岩金矿关系密切且具有继承性。虎拉林岩金矿床的矿石中自然金颗粒粗大，矿体的上部遭到剥蚀，虎拉林河砂金主要来源于虎拉林岩金矿床，砂金可作为岩金的找矿标志。自然金化学-结晶温度图表明砂金的原生Au源为中低温热液矿床。     

Sources for gold,palladium and iridium in deep-sea sediments

Deep-sea sediment cores, one from the Caribbean (calcareous ooze) and three from the Pacific-Antarctic basin (Globigerina ooze, siliceous ooze and pelagic clay) were analysed for Au, Pd, Ir and Mn by neutron activation. The average noble metal contents for 37 samples are: Au (ppb) Pd (ppb) Ir (ppb) 1.05 ± 0.9 3.5 ± 2.8 0.31 ± 0.14 Biogenic and lithogenic (terrigenous) constituents account for much of the noble metal in these sediments. The average noble metal content, particularly that of Au and Ir, shows little variation over the entire suite of four cores despite large differences in the proportions of biogenic and lithogenic fractions. In general neither component is a markedly more significant noble metal sink than the other. However, a strong correlation between Au and CaCO₃ in the Caribbean calcareous ooze suggests that the biogenic fraction is a significant concentrator in this core.Palladium content is more variable than that of Au or Ir and in two of the Antarctic cores some Pd, probably of hydrogenous origin, is present.The Ir content of all cores is higher than that expected of purely terrigenous sources and there is little suggestion of biogenic concentration of the metal. $\text{Au}\text{Ir}$ ratios differ greatly from average continental crust but are similar to oceanic crust. In one of the Antarctic cores some Ir of hydrogenous and of extraterrestrial origin may be present.     

Thallium in the Carlin-type gold deposits

Five Carlin-type sediment-hosted precious metals deposits from the western United States have been analyzed for Tl, Rb, K, Sr, Au, and Ag, and the relationship between Tl, Rb, and K in mineralized and unmineralized rocks has been studied. The Carlin-type gold deposits studied include Carlin, Alligator Ridge, and Jerritt Canyon deposits of Nevada, Mercur deposit of Utah, and North Moccassin deposits of Montana.The mineralized rocks of all five deposits contain significantly high contents of Tl and low K/Tl and high Tl/Sr ratios. The oxidized mineralized rocks of the Carlin and Mercur deposits have higher contents of Tl than carbonaceous rocks while siliceous rocks from most of the deposits contain the lowest Tl concentrations.The K/Tl ratio and the relationship between Tl, Rb, and K can be used to separate mineralized and unmineralized rocks into two distinct populations in order to outline, successfully, potential mineralized areas. The data presented in this paper suggest that Tl is probably a more useful indicator element than Au and other associated elements, at least under certain situations.     

陕西小秦岭金矿床中金的赋存状态及分布规律

陕西小秦岭脉状金矿床中，金的赋存状态及其分布与硫化物的发育程度密切相关，金优先赋存于硫化矿物中，只有当硫化物不发育时，才主要以金矿物形式赋存于石英等矿物中。金矿物的Ａｇ／Ａｕ比率主要受成矿温度、硫化物发育程度、成矿热液中Ｃｌ／Ｓ浓度比值等因素制约。     

津巴布韦哈特利(Hartley)铂矿床地质特征及成因

文章对产于津巴布韦大岩墙内的哈特利(Hartley)铂矿床的地质特征和成因进行研究。津巴布韦大岩墙于新太古代侵入,在津巴布韦克拉通内形成南北段次级岩浆房格局。哈特利铂矿的铂族元素主要分布在杂岩体的中下部,与硫化物密切相关,主要含矿矿物为铋、碲矿物。在岩浆侵位的过程中发生结晶分异,形成了铂族元素和硫化物的垂向分带。哈特利矿床与中国金川等铂族元素矿床相比,其成岩成矿时代早,矿床特征、成矿元素组合方面均有明显不同。     

新疆东天山中段金铜成矿系统研究

以构造动力学体制、成矿机理和含矿建造等为原则,将东天山中段铜金成矿系统划分为晚泥盆世—早石炭世板块碰撞体制下的大南湖—头苏泉岩浆热液金铜、早石炭世板内伸展体制下的阿齐山—雅满苏火山热液铜铁和早二叠世陆内造山体制下的康古尔塔格韧性剪切铜金三个成矿系统。以成矿系统的研究内容和方法为指导,阐述了各成矿系统的地质背景、成矿系统的时空特征、控制因素、成矿系统要素、典型矿床的剖析或成矿系统内各矿床特征的对比,建立了各成矿系统模型,并总结了成矿系统的演化过程和演化谱系。     

铂-钯区域地球化学勘查

以Pt、Pd作为直接指示元素，利用1：20万全国区域化探扫面水系沉积物测量副样和全国超低密度泛滥平原沉积物测量样品，采用化学光谱法测定Pt、Pd和Au三种元素，进行了中国大陆超低密度Pt、Pd地球化学填图，在川滇等地球化学省开展了1：20万Pt、Pd区域化探，发现中国大陆存在几个重要的Pt、Pd地球化学省和一些区域异常。中国大陆Pt、Pd丰度低：Pt0.42ng/g,Pd0.35ng/g，呈不均匀分布。在活动带Pt、Pd有显著富集。川滇是一个重要的铂族元素成矿省，除镁铁-超镁铁岩及在关的铂族元素矿化外，在黑色岩系以及西南暗色岩系等岩层中Pt、Pd等显著富集，并且发现了非传统类型的铂族矿化。     

Paleoproterozoic,turbidite-hosted,gold deposits of the Ashanti gold belt (Ghana,West Africa): Comparative analysis of turbidite-hosted gold deposits and an updated genetic model

The Paleoproterozoic gold deposits of the Ashanti gold belt, Ghana, occur mainly as auriferous quartz veins in graphitic shears proximal to contacts between deformed and metamorphosed turbidites and tholeiitic volcanics (alternately block-faulted Tarkwaian sediments). They are suggested in this article to belong to that class of gold deposits recognized as ‘turbidite-hosted’. Hence, evidence from previous investigations of turbidite-hosted and turbidite-associated gold deposits occurring in circumstances roughly similar to the Ashanti deposits are used, where relevant, to produce an updated genetic model for the latter.Given the relatively significant amounts of graphite associated with the major Ashanti deposits, the role of non-carbonate carbon is assessed in the light of conclusions reached by work on other turbidite-hosted and turbidite-associated gold belts. Conclusions as to the origins of mineralizing fluids and temporary repositories of gold (auriferous interflow sediments) reached by work on these other belts are also analysed.A concept of the tectonic development of the Ashanti belt-Kumasi basin area, introduced in this article, is deemed to be critical to the origin of the Ashanti gold deposits. It encompasses the role of non-carbonate carbon, turbidites, and the primary sources and secondary repositories of Au and As in the genesis of the major Ashanti gold deposits. It examines the significance of the intimate relationship between calc alkaline volcanism and the basin sediments, the occurrences of felsic metasandstones in transition-zone sediments, and TTG granitic material and fragments of chemical sediments in turbidites: all of which are incompatible with one or the other of existing concepts of tectonic development in the area.     

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.