Kinetic modelling of geochemical processes at the Aitik mining waste rock site in northern Sweden

A steady-state geochemical model has been developed to study water-rock interactions controlling metal release from waste rock heaps at the Aitik Cu mine in northern Sweden. The Cu release in drainage waters from the site is of environmental concern. The waste rock heaps are treated as single completely mixed flow-through reactors. The geochemical model includes kinetices of sulphide and primary silicate mineral weathering, heterogeneous equilibrium with secondary mineral phases and speciation equilibrium. Field monitoring of drainage water composition provides a basis for evaluation of model performance.The relative rate of oxidative weathering of sulphides and dissolution of primary silicate minerals, using published kinetic data, are consistent with net proton and base cation fluxes at the site. The overall rate of Fe²⁺ oxidation within the heap is three orders of magnitude faster than that which could be explained by surface-catalysed reaction kinetics. This suggests significant activity of iron-oxidizing bacteria. The absolute weathering rates of sulphides and silicate minerals, normalized to a measured BET surface area, are approximately two orders of magnitude lower at field scale than published rates from laboratory experiments. Because of the relative absence of carbonate minerals, the weathering of biotite and plagioclase feldspar are important sources of alkalinity.     

Geochemical study of different-aged mining dump materials in the Freiberg mining district, Germany

Historical mining dumps are useful archives for the investigation of weathering processes. The objective of this study was to investigate the weathering behavior of waste-rock material derived from the 800-year-old silver ore mining in Freiberg, Germany. For identifying time-dependent weathering indices, dumped material of four dumps of different ages and corresponding rock was examined regarding the geochemical composition. The dumped material is characterized by high contents of heavy metal containing sulfidic ores, such as pyrite, arsenopyrite, sphalerite and galena. Acid mine drainage is produced by the oxidative weathering of the sulfide minerals and causes the increased dissolving of soluble metals with increasing age of dumps. As a result of these weathering processes, a clear depletion of chalcophile elements in the older dump material (800 years) compared to the youngest dump (100 years) was observed. In the soil horizons downstream the dumps, high quantities of heavy metals (e.g., up to 12,000 ppm As, 3,300 ppm Pb, 640 ppm Zn), mainly adsorbed on organic matter, were determined and indicate a time-dependent element transfer from the dumps into their surrounding soils.     

基于灾害链效应的小秦岭乱石沟矿渣堆危险性评价

矿产开采过程中,大规模不合理的矿渣堆弃以及高强度降雨等所引发的矿渣碎屑流,对矿山的正常生产和人员安全带来了巨大的风险。由于矿渣堆普遍沿沟谷呈串珠状分布,若下级渣堆受到上级矿渣碎屑流的冲击、加载作用,其失稳起动概率及渣流量将明显增加,这种空间逐级影响所表现出的灾害链效应是矿渣碎屑流灾害作用的重要特征。以小秦岭乱石沟为例,在对研究区内矿渣堆详细调查的基础上,首先以矿渣堆高度、坡度、方量、是否堆载振动、底床坡度以及降雨汇流累积量6项指标对矿渣堆的危险性进行评价。其次,采用UBCDFLOW方法,考虑碎屑流的路径宽度、平均坡角及流动类型,估算碎屑流的滑移距离。最后,在此基础上从风险评价与预测的角度出发,综合考虑矿渣堆碎屑流的链状逐级影响,以及下级渣堆位于上级渣堆碎屑流冲击范围内的相对位置,得到灾害链效应下的矿渣堆危险性评价。计算结果表明考虑灾害链效应后,乱石沟内受碎屑流影响的矿渣堆的破坏概率明显增加,研究结果也为矿山沟谷流域矿渣堆灾害的风险评价及防治规划设计提供依据。     

Chemical weathering of granite under acid rainfall environment, Korea

Chemical weathering was investigated by collecting samples from five selected weathering profiles in a high elevation granitic environment located in Seoul, Korea. The overall changes of chemistry and mineralogical textures were examined reflecting weathering degrees of the samples, using polarization microscopy, X-ray diffraction (XRD), electron probe micro analysis (EPMA), X-ray fluorescence spectroscopy (XRF), and inductively coupled plasma–mass spectroscopy (ICP–MS). The chemical distribution in the weathering profiles shows that few trace elements are slightly immobile, whereas most major (particularly Ca and Na) and trace elements are mobile from the beginning of the granite weathering. On the other hand, there were mineralogical changes initiated from a plagioclase breakdown, which shows a characteristic circular dissolved pattern caused by a preferential leaching of Ca cation along grain boundaries and zoning. The biotite in that region is also supposed to be sensitive to exterior environmental condition and may be easily dissolved by acidic percolated water. As a result, it seems that some rock-forming minerals in the granitic rock located in Seoul are significantly unstable due to the environmental condition of acidic rainfall and steep slopes, where they are susceptible to be dissolved incongruently leading some elements to be highly depleted.     

Geochemical features of rocks,stream sediments,and soils of the Fiume Grande Valley (Calabria,Italy)

The role of both natural weathering and anthropogenic pollution in controlling the distribution of major oxides and several trace elements in soils, stream sediments, and rocks of the Fiume Grande catchment was evaluated. The contents of major oxides and trace elements in soils appear to be governed by weathering and pedogenetic processes, although the use of fertilizers in agriculture could also partly affect K₂O and P₂O₅ contents. Stream sediments have concentrations of major oxides (except CaO) very similar to soils, as relevant amounts of soil materials are supplied to the stream channels by erosive phenomena. In contrast, stream sediments have concentrations of Cr, Co, Ni, Zn, As, and Pb significantly higher than those of soils, probably due to different conditions and rates of mobility of these elements within the three considered matrices and/or disposal of wastes in the drainage network. Comparison of the concentrations of PHEs in soils with the maximum admissible contents established by the Italian law shows that these limits are too restrictive in some cases and too permissive in other ones. The approach of setting these limits with no consideration for the local geological–geochemical framework may lead to improper management of the territory and its resources. Electronic supplementary material Supplementary material is available in the online version of this article at and is accessible for authorized users.     

江西武宁县石门寺钨铜矿区风化作用过程中W、Cu等元素的表生地球化学行为(之一)

以江西省武宁县石门寺钨铜矿区燕山期和晋宁期岩体风化作用过程中W、Cu等元素的表生地球化学行为为研究对象,通过反映风化程度的化学风化指数CIA、风化作用过程中组分得失的估算、不同介质中W、Cu等成矿元素的含量变化及大离子亲石元素表生地球化学行为等方法的研究表明,石门寺钨铜矿区2个时期岩体元素淋失与风化强度有关,土壤剖面中碱金属、碱土金属元素大量淋失,而W、Cu等成矿元素在土壤B层中显著富集;从岩石到土壤、再到水系沉积物风化过程中,W、Cu等成矿元素含量逐渐升高,为此,一级水系沉积物和B层土壤是赣北九岭W、Sn、Cu、Mo多金属矿集区地球化学找矿的绝佳采样介质,是矿集区内找矿新突破的有效手段。     

江西武宁县石门寺钨铜矿区风化作用过程中W、Cu等元素的表生地球化学行为（之一）

以江西省武宁县石门寺钨铜矿区燕山期和晋宁期岩体风化作用过程中W、Cu等元素的表生地球化学行为为研究对象,通过反映风化程度的化学风化指数CIA、风化作用过程中组分得失的估算、不同介质中W、Cu等成矿元素的含量变化及大离子亲石元素表生地球化学行为等方法的研究表明,石门寺钨铜矿区2个时期岩体元素淋失与风化强度有关,土壤剖面中碱金属、碱土金属元素大量淋失,而W、Cu等成矿元素在土壤B层中显著富集;从岩石到土壤、再到水系沉积物风化过程中,W、Cu等成矿元素含量逐渐升高,为此,一级水系沉积物和B层土壤是赣北九岭W、Sn、Cu、Mo多金属矿集区地球化学找矿的绝佳采样介质,是矿集区内找矿新突破的有效手段。     

化学风化作用中的稀土元素行为及其影响因素

地表风化作用长期以来一直是地球和环境科学研究的焦点问题。风化作用中微量元素地球化学行为的研究不但有助于对一系列全球性问题的认识和理解,而且有助于许多与人类生存密切相关的环境问题的解决。系统总结了近年来国内外在风化作用中的稀土元素地球化学研究领域的主要内容和最新进展,着重介绍了风化壳中稀土元素的分布特征、Ce异常成因、稀土元素的赋存状态和迁移方式、影响稀土元素分布和循环的主要因素,以及风化作用稀土元素地球化学的主要研究方法。最后,分析指出有机质和微生物作用对稀土行为的影响是未来的重要研究方向。     

云南省西部地区土壤地球化学基准值特征及成因分析

基于云南省西部地区土地质量地球化学调查数据资料,采用具有稳健特性的中位数表征深层土壤52种元素的地球化学基准值,对比分析了不同成土母质和用地类型的元素分布特征和富集贫化规律,进一步采用因子分析从元素组合特征角度剖析了地球化学基准值的成因机制.结果 表明:研究区土壤中铁族元素、亲铜元素、矿化剂和卤族元素、稀有稀散稀土元素...     

Mineralogical and geochemical alteration of low-grade metamorphic black slates due to oxidative weathering

Low-grade metamorphic black slates of Silurian and Lower Devonian ages (from the Thüringisches Schiefergebirge in Germany) were investigated to identify mineralogical and geochemical alterations that occur during the oxidative weathering black slates.The slates exhibit an intense total organic carbon decrease (>90 wt%) due to oxidative weathering. The organic matter in black slate consists mainly of non-pyrolysable material with only minor portions of pyrolysable material. In contrast to the non-pyrolysable organic matter, the concentration of pyrolysable organic matter is not decreased during weathering. Heating experiments have yielded information about a potential protection of pyrolysable organic matter against weathering, which is probably caused by a structural configuration or the intergrowth of organic matter and illite.The slates consist mainly of illite. Iron oxide (goethite) and phosphate encrustations were formed on slate surfaces as a result of oxidative and acid weathering of both iron sulfide and monazite. Kaolinite often occurs as an older encrustation beneath the iron oxide encrustations. Encrustations of iron oxide and phosphate are major sinks for trace elements, released during oxidative weathering.     

黔北白云岩红色风化壳元素地球化学特征

选取贵州高原喀斯特地区典型白云岩风化剖面作为研究对象,探讨了红土剖面元素迁移特征及其影响因素,为进一步认识红色风化壳元素地球化学特征提供依据。结果表明:（1）红土剖面中土壤样品（XPS-4~XPS-25）Fe、K、Mn常量元素及Co、Pb、Zn微量元素的分布曲线相对于其他元素靠近 UCC,元素Mg、Ca、Na、Ti和 Li、Cr、Ba、V 的数据点则显著偏离了上部陆壳的平均组成。（2）元素对协变分析得出Ti与Fe、Ba和V的积累特征一致,呈增加趋势;Ti与Mg呈反向变化特征。（3）以Ti为参比元素的剖面迁移特征表明,绝大部分元素的地球化学行为表现为迁移淋失,仅 Fe 、Cr和V 富集。K、Ba总体上呈迁出趋势,个别层段有轻微富集;Na和Co在风化原岩处有一个富集端点。元素在风化过程中的迁移聚集与土壤剖面的pH值和剖面结构变化、粘土矿物和有机质等的吸附有关。      

皖南姚村岩体花岗岩风化壳稀土元素赋存特征

皖南地区花岗岩风化壳中稀土元素普遍富集，局部已成为矿床，其中，郎溪县姚村岩体风化壳富集程度较高。LA- ICP- MS锆石U- Pb定年表明，姚村花岗岩体的形成年龄为127. 9±1. 4 Ma，属于皖南地区燕山期晚期岩浆作用的产物。风化壳可细分为残坡积层（A）、强半风化层（C1）、过渡层（C2）、弱半风化层（C3）和基岩（D） 5层。稀土总量在纵向剖面上呈“波浪式”分布，各层稀土分布型式表现出对原岩的继承性。风化壳稀土配分型式与基岩一致， 富集LREE，轻重稀土分馏明显\[(La/Yb)N=15. 6\]，但总含量明显更高。基岩∑REE为338×10-6，半风化层∑REE最高达642×10-6，富集约两倍。风化壳物质由风化残余主矿物（石英、钾长石、斜长石、黑云母）、黏土矿物（高岭石、埃洛石、伊利石、三水铝石等）和副矿物（锆石、磷灰石、榍石等）等组成。黏土矿物以伊利石含量最高，指示风化壳发育不成熟。REE与埃洛石含量明显正相关，与其他黏土矿物关系不明显。（含）稀土矿物（尤其是榍石）对风化壳中稀土元素的贡献量超过 50%，其次为斜长石，是风化壳中REE的重要来源。     

皖南姚村岩体花岗岩风化壳稀土元素赋存特征

皖南地区花岗岩风化壳中稀土元素普遍富集，局部已成为矿床，其中，郎溪县姚村岩体风化壳富集程度较高。LA- ICP- MS锆石U- Pb定年表明，姚村花岗岩体的形成年龄为127.9±1.4 Ma，属于皖南地区燕山期晚期岩浆作用的产物。风化壳可细分为残坡积层（A）、强半风化层（C1）、过渡层（C2）、弱风化层（C3）和基岩（D）五层。稀土总量在纵向剖面上呈“波浪式”分布，各层稀土分布型式表现出对原岩的继承性。风化壳稀土配分型式与基岩一致， 富集LREE，轻重稀土分馏明显(La/Yb)N=15.6），但总含量明显更高。基岩∑REE为338×10-6，半风化层∑REE最高达642×10-6，富集约两倍。风化壳物质由风化残余主矿物（石英、钾长石、斜长石、黑云母）、黏土矿物（高岭石、埃洛石、伊利石、三水铝石等）和副矿物（锆石、磷灰石、榍石等）等组成。黏土矿物以伊利石含量最高，指示风化壳发育不成熟。REE与埃洛石含量明显正相关，与其他黏土矿物关系不明显。（含）稀土矿物（尤其是榍石）对风化壳中稀土元素的贡献量超过百分之五十，其次为斜长石，是风化壳中REE的重要来源。     

Factor Analysis of Soil and Attic-dust to Separate Mining and Metallurgy Influence, Meza Valley, Slovenia

Based on the factor analysis of chemical elements determined in topsoil (0–5 cm) and attic-dust, two natural and two man-made (anthropogenic) geochemical associations were discovered in the Meza valley, an old mining and metallurgic area. The natural geochemical association (Al-Ce-Co-K-La-Li-Nb-Rb-Sc-Th-Ti-V) is influenced mainly by weathering of metamorphic rocks, while the anthropogenic association (Ca-Mg) was determined in an area of carbonate rock outcrops. The man-made associations are a result of lead production (Ag-As-Cd-Mo-Pb-S-Sb-Sn-Zn) and iron production (Co-Cr-Mo-Ni-W).     

Lichens as bioindicators in volcanic areas: Mt. Etna and Vulcano Island (Italy)

 The aim of this paper is to verify whether lichens have the capacity to accumulate atmospheric contaminators linked to volcanic activity. About 100 lichens were collected in 1994 and 1995 from two active volcanic areas in Italy: Mount Etna and Vulcano Island. Twenty-seven elements were analyzed for each individual lichen using Instrumental Neutronic Activation Analysis and Inductively Coupled Plasma-Mass Spectrometry. Lichen composition reflects the contribution of the volcanic particulate material, and the two areas investigated can be distinguished on the basis of the concentration of some lithophile elements. Moreover, the distribution in lichens of the elements (As, Sb, Br, Pb) – derived from gas emissions (plume, fumaroles) – also shows different geochemical trends on Mt. Etna and Vulcano. Received: 20 April 1998 · Accepted: 4 July 1998     

安徽江淮地区土壤微量元素分布特征及成因分析

多目标区域地球化学调查作为生态地球化学调查的基础工作,以快速查明表层土壤及其背景地球化学元素分布为目的.本文以安徽江淮地区多目标区域地球化学调查结果为基础,对安徽江淮地区耕地土壤及其母质中主要元素分布特征及其成因进行了分析研究,结果得出:(1)大多数地区表层土壤微量元素含量与深层具有一致性和继承性;(2)各地土壤微量元素分布特征主要受成土母质类型控制,说明其成因与成土母质和成土过程等因素有关;(3)耕地土壤微量元素含量的变异受施肥、灌溉和耕作方式等人为因素影响较大,且存在较大的地区差异性.     

Accumulation of copper in the Permian Kupferschiefer: A result of post-depositional redox reactions

Within the Central European Zechstein Basin the Permian Kupferschiefer has been deposited under anoxic conditions. In most parts of the basin, the metal content does not exceed values commonly observed in black shales. However, in areas near to the Zechstein sea-shore which are simultaneously related to rift zones a significant base metal enrichment is observed. Organic geochemical analyses of the copper-mineralized sections in the Kupferschiefer from Southwest Poland show that significant changes in the composition of organic matter are associated with the metal enrichment processes. Porphyrins, commonly abundant constituents of the shale, have been decomposed by oxidizing fluids. Additionally, aliphatic hydrocarbons have been largely removed from the bitumen and alkylated aromatic systems were affected by side-chain degradation. This particular type of alteration is explained by ascending oxidizing solutions which transported high amounts of base metals from Lower Permian red beds into the Kupferschiefer horizon acting as a geochemical trap. The metal precipitation is suggested to be a result of thermochemical sulphide production with organic matter acting as hydrogen source. In areas such as the Lower Rhine Basin in the bottom section of the Kupferschiefer the base metals lead and zinc as well as barium have been accumulated from basinal Carboniferous formation waters. Copper enrichment is not observed because potential source rocks are missing in this area. However, the observed compositional changes of the organic matter do not point towards thermochemical redox processes.     

Melt extraction and melt refertilization in mantle peridotite of the Coast Range ophiolite: an LA–ICP–MS study

The middle Jurassic Coast Range Ophiolite (CRO) is one of the most important tectonic elements in western California, cropping out as tectonically dismembered elements that extend 700 km from south to north. The volcanic and plutonic sections are commonly interpreted to represent a supra-subduction zone (SSZ) ophiolite, but models specifying a mid-ocean ridge origin have also been proposed. These contrasting interpretations have distinctly different implications for the tectonic evolution of the western Cordillera in the Jurassic. If an SSZ origin is confirmed, we can use the underlying mantle peridotites to elucidate melt processes in the mantle wedge above the subduction zone. This study uses laser ablation–inductively coupled plasma–mass spectrometry (LA–ICP–MS) to study pyroxenes in peridotites from four mantle sections in the CRO. Trace element signatures of these pyroxenes record magmatic processes characteristic of both mid-ocean ridge and supra-subduction zone settings. Group A clinopyroxene display enriched REE concentrations [e.g., Gd (0.938–1.663 ppm), Dy (1.79–3.24 ppm), Yb (1.216–2.047 ppm), and Lu (0.168–0.290 ppm)], compared to Group B and C clinopyroxenes [e.g., Gd (0.048–0.055 ppm), Dy (0.114–0.225 ppm), Yb (0.128–0.340 ppm), and Lu (0.022–0.05 ppm)]. These patterns are also evident in orthopyroxene. The differences between these geochemical signatures could be a result of a heterogeneous upper mantle or different degrees of partial melting of the upper mantle. It will be shown that CRO peridotites were generated through fractional melting. The shapes of REE patterns are consistent with variable degrees of melting initiated within the garnet stability field. Models call for 3% dry partial melting of MORB-source asthenosphere in the garnet lherzolite field for abyssal peridotites and 15–20% further partial melting in the spinel lherzolite field, possibly by hydrous melting for SSZ peridotites. These geochemical variations and occurrence of both styles of melting regimes within close spatial and temporal association suggest that certain segments of the CRO may represent oceanic lithosphere, attached to a large-offset transform fault and that east-dipping, proto-Franciscan subduction may have been initiated along this transform.     

Geochemical Characteristics of a Veinlet Kupferschiefer Profile from the Lubin Mine, Southwestern Poland

Previous studies have shown that the ascending, oxidizing brines play a very important role in Kupferschiefer mineralization. Fractures could be the pathway of the brines. In order to clarify the influences of the brines on bulk organic matter, aromatic hydrocarbons and Kupferschiefer mineralization, one veinlet Kupferschiefer profile from the Lubin mine, southwestern Poland was studied with the microscopic, geochemical and Rock-Eval methods. The microscopic results indicate that organic matter of the veinlet sample consists dominantly of bitumen. Its extract content is higher than in other samples. The dominant aromatic compounds are naphthalene and alkylated naphthalenes (Na-PAH), which have migrated into the veinlet sample from other sediments. The content of phenanthrene and its methylated derivatives (Ph-PAH) is much lower than in other samples. The reason may be due to their heavier mass than Na-PAH. It is more difficult for Ph-PAH to migrate. The Na-PAH was probably removed from the shale by dist     

Mineralogical and geochemical characterisation of open-air tailing and waste-rock dumps from the Libiola Fe-Cu sulphide mine (Eastern Liguria,Italy)

Active acid mine drainage (AMD) processes at the Libiola Fe-Cu sulphides mine are mainly triggered by water–rock interaction occurring within open-air tailing and waste-rock dumps. These processes are mainly controlled by exposure to weathering agents, the grain size of the dumped materials, and by the quantity of sulphides, the sulphide types, and their mode of occurrence. Due to these factors, several paragenetic stages of evolution have been recognised at different depths at different sites and within the same site. The dump samples were investigated with mineralogical (reflected- and transmitted-light optical microscopy, XRPD, and SEM-EDS) and geochemical (ICP-AES, Leco) techniques. The AMD evaluation of the tailing and waste-rock samples was performed by calculating the Maximum Potential Acidity, the Acid Neutralising Capacity, (and the Net Acid Producing Potential. The results allowed us to demonstrate that the open-air tailings had already superseded their AMD apex and are now practically inert material composed mainly of stable goethite ± lepidocrocite ± hematite assemblages. On the contrary, the sulphide-rich waste rocks still have a strong potential to produce long term AMD, causing the acidification of circulating waters and the release of several hazardous elements.