从铜的地球化学行为探讨常宁铜鼓塘富铜矿床的成因

常宁铜鼓塘富铜(银铀)矿床,以Ⅵ号主矿体为代表,具有以辉铜矿为主的矿物组合。本文根据Cu、(Ag)的地球化学行为,阐述了不同条件下,Cu、Fe与S、O的亲疏倾向,从而形成各矿体独具特色的矿物共生组合特征。进而讨论了矿床的特定成矿环境和典型岩溶成因。最后,笔者综合分析了多种有利成矿因素,指出金鸡岭背斜及其以北地段,是普查同类型富铜矿床的远景地区。     

Geological and SHRIMP II U-Pb constraints on the age and origin of the Breves Cu-Au-(W-Bi-Sn) deposit,Carajás,Brazil

The Breves deposit in the Carajás Copper-Gold Belt, Brazil, a member of the Cu-Au-(W-Bi-Sn) group of deposits, contains about 50 Mt of 1.22% Cu, 0.75 g/t Au, 2.4 g/t Ag, 1,200 g/t W, 70 g/t Sn, 175 g/t Mo and 75 g/t Bi. It is hosted by sandstones and siltstones of the Águas Claras Formation (minimum age of 2,681±5 Ma) in the roof zone of a complex, highly altered granite intrusion. The mineralisation is disseminated in a greisenized zone, resulting from alteration of probable monzogranites and syenogranites. The ore-bearing greisen contains abundant xenomorphic quartz in association with Fe-chlorite and muscovite. The gangue assemblage also includes fluorite, tourmaline, and minor amounts of monazite, xenotime, chlorapatite, thorite, zircon, calcite, siderite and bastnäesite. Copper mineralisation is dominated by chalcopyrite associated with pyrite, arsenopyrite, pyrrhotite and molybdenite. Gold particles, in equilibrium with native bismuth, are common as inclusions in chalcopyrite. The greisen contains sub-economic concentrations of tungsten and niobium that are related to the presence of ferberite, qitianlingite and Nb-rutile. SHRIMP II zircon dating of the host granites gives ²⁰⁷Pb/²⁰⁶Pb ages of 1,878±8 and 1,880±9 Ma for two phases, and a combined age of 1,879±6 Ma. SHRIMP II dating of monazite and xenotime grains in late- to post-mineralisation veins gives a combined ²⁰⁷Pb/²⁰⁶Pb age of 1,872±7 Ma, indistinguishable from the ages of the granites. This provides a genetic connection between the Breves deposit and the ca. 1.88 Ga A-type granite magmatism that typifies the Carajás Belt as part of a much larger, intracratonic magmatic province that extends over much of the Amazonian Craton. The recognition of this association has exploration implications, not only for the geophysical signature of the granite roof zones, but also for likely geochemical dispersion around the deposits of this type.Editorial handling: G. Beaudoin     

The exposure of global base metal resources to water criticality,scarcity and climate change

Mining operations are vital to sustaining our modern way of life and are often located in areas that have limited water supplies or are at an increased risk of the effects of climate change. However, few studies have considered the interactions between the mining industry and water resources on a global scale. These interactions are often complex and site specific, and so an understanding of the local water contexts of individual mining projects is required before associated risks can be adequately assessed. Here, we address this important issue by providing the first quantitative assessment of the contextual water risks facing the global base metal mining industry, focusing on the location of known copper, lead, zinc and nickel resources.The relative exposure of copper, lead-zinc and nickel resources to water risks were assessed by considering a variety of spatial water indices, with each providing a different perspective of contextual water risks. Provincial data was considered for water criticality (CRIT), supply risk (SR), vulnerability to supply restrictions (VSR) and the environmental implications (EI) of water use. Additionally, watershed or sub-basin scale data for blue water scarcity (BWS), the water stress index (WSI), the available water remaining (AWaRe), basin internal evaporation recycling (BIER) ratios and the water depletion index (WDI) were also considered, as these have particular relevance for life cycle assessment and water footprint studies. All of the indices indicate that global copper resources are more exposed to water risks than lead-zinc or nickel resources, in part due to the large copper endowment of countries such as Chile and Peru that experience high water criticality, stress and scarcity. Copper resources are located in regions where water consumption is more likely to contribute to long-term decreases in water availability and also where evaporation is less likely to re-precipitate in the same drainage basin to cause surface-runoff or groundwater recharge.The global resource datasets were also assessed against regional Köppen-Geiger climate classifications for the observed period 1951–2000 and changes to 2100 using the Intergovernmental Panel on Climate Change’s A1FI, A2, B1 and B2 emission scenarios. The results indicate that regions containing copper resources are also more exposed to likely changes in climate than those containing lead-zinc or nickel resources. Overall, regions containing 27–32% (473–574 Mt Cu) of copper, 17–29% (139–241 Mt Pb + Zn) of lead-zinc and 6–13% (19–39 Mt Ni) of nickel resources may have a major climate re-classification as a result of anthropogenic climate change. A further 15–23% (262–412 Mt) of copper, 23–32% (195–270 Mt) of lead-zinc and 29–32% (84–94 Mt) of nickel are exposed to regional precipitation or temperature sub-classification changes. These climate changes are likely to alter the water balance, water quality and infrastructure risks at mining and mineral processing operations. Effective management of long-term changes to mine site water and climate risks requires the further adoption of anticipatory risk management strategies.     

中条山胡篦型铜矿床深部特殊类型矿脉(巢)的地质特征研究

中条山地区胡篦型铜矿深部出现的四种特殊类型矿脉（巢）,其产出地质特征表明胡篦型铜矿大脉状铜矿化不完全限于矿层之内,在特殊地质环境下也可形成于矿层外部。胡篦型铜矿床在热液成矿作用晚期不是一个简单的铜质迭加富集,而是经历了一个复杂的物质演变过程,且有钴组份参与了成矿,从而丰富了矿床成因的地质认识,拓宽了今后找矿思路。     

武山铜矿北矿带ICu矿体砷的分布规律

武山铜矿化矿带ＩＣｕ矿体是高砷矿体,分析了砷在各金属矿物中含量及分配情况和含砷量的分布规律,确定了高砷采场或矿段,指出了进行矿石质量控制,配矿管理的降砷途径。     

Urease-Hemmtest für wirkungsbezogene Untersuchungen der Bindungsformen von Kupfer in Wässern und Bodeneluaten

Urease Inhibition Test for Effect-related Investigations of Copper Speciation in Water and Soil Extracts In 80 different water samples, the inhibition effect of cupric ions was measured by application of a simple urease inhibition test. In relation to the total copper concentration, the inhibition permits an effect-related classification of drinking water, rain water, spring water, surface water, leakage water, wastewater, and soil extracts. Drinking water contains high parts of cupric ions in the free hydrated form. Their copper content results in high urease inhibition and is caused by using copper pipes in house plumbing. In leakage water, wastewater, and soil extracts, cupric ions are mainly complexed by organic compounds in the sample matrix. Hence, the inhibition effects are low. In soil extracts, the urease inhibition increased after an UV-decomposition procedure, but a decreasing effect was observed for a surface and a drinking water sample, respectively. The chemical oxygen demand and UV-absorbance at 255 nm measured before and after the procedure were correlated to the content of organic compounds, i.e., humic acid. In most samples, the organic matrix was not decomposed completely. The oxidizing decomposition apparently forms further complexing agents, which suppress the inhibition effect of cupric ions. In the rain water samples investigated, the content of organic compounds depended on rain intensity. The chemical oxygen demand and UV-absorbance, respectively, were low for rain water collected during strong rain periods and increased with decreasing rain intensity. The rain water trickled over sheet-lead roof showed an increase of urease inhibition compared with the simultaneously collected rain. Consequently, a decomposition of organic matrix could be demonstrated in rain water by use of the urease inhibition test.     

Gravity and magnetic field characteristics and regional ore prospecting of the Yili ancient continent,West Tianshan,Xinjiang Uygur Autonomous Region,China

Gold, iron, copper, lead-zinc and other mineral exploration in West Tianshan, Xinjiang Uygur Autonomous Region, has made remarkable progress in recent years. However, due to the dispute on the tectonic division of West Tianshan, the ore-controlling factors and the regional metallogenic laws are controversial. The authors analyze regional gravity data and notice that the high-value region corresponds to the Yili ancient continent, thus the southeastern boundary of the Yili ancient continent is delineated. Comparative analysis of gravity, aeromagnetic and geologic data reveals that the Tulasu basin, where some medium to large epithermal gold deposits locate, lies above the Yili ancient continent; the Yili Carboniferous-Permian rift extends in E-W direction, numbers of copper deposits have been found in the mid-west section of the rift which lies above the Yili ancient continent, whereas few copper deposits have been discovered in the east section which is outside the Yili ancient continent. Accordingly, the Yili ancient continent may he rich in gold, copper and other metal elements; the metal-bearing hydrothermal solution moves up with the activity of magmatism, and deposits in the favorable places (the Tulasu basin and the Yili Carboniferous-Permian rift), forming numerous small and medium gold, copper deposits, as well as some large and super-large gold deposits. Therefore, the tectonic-magmatic hydrothermal zone above the Yili ancient continent should be the prospective area for epithermal gold and copper polymetallic deposits.     

Adsorption characteristics of copper ion on nanoporous silica

Adsorption by nanoporous media is critically involved in many fundamental geological and geochemical processes including chemical weathering,element migration and enrichment,environmental pollution,etc.Yet,the adsorption behavior of metal ions on nanoporous materials has not been systematically investigated.In this study,MCM-41 material with a monodisperse pore size(4.4 nm)and a large BET specific surface area(839 m^2/g)was hydrothermally prepared and used as a model silica adsorbent to study the adsorption characteristics of Cu^2+as a representative metal ion.The Cu^2+adsorption capacity was found to increase with increasing suspension pH in the range from 3 to 5 and to decrease in the presence of NaNO3.At 25℃,pH=5,and a solid-to-liquid ratio of 5 g/L,the adsorption capacity was determined to be 0.29 mg/g,which can be converted to a dimensionless partition coefficient of 45,indicating a strong enriching effect of nanoporous silica.The adsorption isotherm and kinetic data were fitted to several commonly used thermodynamic,kinetic,and diffusion models.The adsorption mechanism was also studied by Fourier transform infrared spectroscopy,X-ray photoelectron spectroscopy and synchrotron-based X-ray absorption spectroscopy.The results suggest that Cu2+ion adsorption is an entropy-driven endothermal process,possibly involving both outer-sphere and inner-sphere complexes.     

海洋沉积物中铜含量测量不确定度评定 ——电热板加热消解法与微波消解法的比对

电热板加热消解法和微波消解法是目前海洋沉积物样品消解的常用方法。为了比较这两种处理方法对检测结果准确性的影响程度,文章依据《测量不确定度的评定与表示》技术规定中的相关要求对海洋沉积物中铜含量测定过程中采取的两种消解方法进行了不确定度评定与对比,建立了模型,并对各不确定度分量进行分析和量化,计算出两种消解方法测量沉积物中铜含量的相对合成不确定度分别为0.06721和0.04033,扩展不确定度分别为4.0mg/kg和2.4mg/kg。通过比较两种消解方法对测定结果不确定度的贡献,发现微波消解法明显优于电热板加热法。     

安基山铜矿床地质—地球物理模型及其找矿意义

安基山铜矿床是长江中下游成矿带东段的典型矿床之一,对控制该矿床的3条主勘探线的钻孔岩心进行了系统的物性测定,建立了矿床地质体与物性体的相关关系,通过对物性体正演的重、磁异常与实测异常对比,以及对矿区地球物理场的平而和剖面分布规律的总结,建立了安基山铜矿床的地质-地球物理模型,在此基础上建立了具有普遍意义的中等剥蚀深度下的同类矿床的地质一地球物理模型,阐述了模型的找矿意义。