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1.
The Gulf of Mannar along the Tuticorin coast is a coral base of the southeast coast of India. To obtain a preliminary view of its environmental conditions, geochemical distribution of major elements (Si, Al, Fe, Ca, Mg, Na, K, P), trace elements (Mn, Cr, Cu, Ni, Co, Pb, Zn, Cd) and acid leachable elements (Fe, Mn, Cr, Cu, Ni, Co, Pb, Zn, Cd) were analyzed in surface sediment samples from two seasons. Geochemical fractionation confirmed the lithogenic origin of metals, which were mainly associated with the detrital phase. The sediments in the gulf are sandy with abundant calcareous debris, which controls the distribution of total and acid leachable elements. Enrichment factors relative to crust vary by a magnitude of two to three and the presence of trace metals indicates the input of Cr, Pb, Cd, Cu and Zn in both forms through industrial activities. Factor analysis supports the above observation with higher loadings on acid leachable elements and its association with CaCO3. The increase in concentration of trace metals (Cr, Pb, Cd, Cu, Co, Ni, Zn) along the Gulf of Mannar indicates that the area has been contaminated by the input from riverine sources and the industries nearby. The present study indicates that other sources should be evaluated in the long-term monitoring program.  相似文献   

2.
云浮黄铁矿利用过程中微量毒害元素的环境化学活动性   总被引：13，自引：3，他引：13  
为了解云浮黄铁矿利用过程中微量毒害元素的环境地球化学行为，客观评价它们对环境质量的影响，利用元素结合形态的连续提取实验方法，分析了云浮黄铁矿及其工业废渣中Co,Ni,Cu,Zn,As,Se,Cd,Sn,Sb,Pb和Tl等11种毒害元素的形态及化学活动性。结果表明，黄铁矿中大部分微量毒害元素都有着极强的化学活动性，各元素活动态浸出比例依次为Co96.3%,Se91.9%,Cu90.3%,Cd90.0%,Pb89.7%,Zn88.6%,Sb82.5%,Ni80.6%，Sn70%,Tl55.1%和As31.9％，元素As和Tl主要赋存于硫化物和硅酸盐矿物相中，另有少量的Cu,Pb和Sb可能赋存于碳酸盐矿物相中，其他元素则主要赋存于硫化物矿物相中。与黄铁矿相比，飞灰和灰渣中各元素可交换态和碳酸盐结合态所占的比例明显减少。废渣中各元素的化学活动性表现出很大的差别，其中Cu,Zn和Cd的化学活动性最强，活性态浸出比例在90％以上；其次是Co,Ni,Se,Pb和Tl，浸出比例在50％左右；Sb,As和Sn的稳定性较高，浸出比例分别为1％、5％和14％左右；飞灰中微量毒害元素的活动性均高于灰渣。  相似文献   

3.
The technique of diffusive gradients in thin films (DGT) was applied to obtain high-resolution vertical profiles of trace metals in sediment porewater of a eutrophic lake, Lake Chaohu. All sampling sediments were under anaerobic conditions with Eh values below 0, the redox potential profile in M4 was relatively stable, and higher Eh values in M4 than that in M1 were observed due to hydrodynamic effects. Fe, Mn and As exhibited closely corresponding profiles due to the co-release of Fe and Mn oxides and the reduction of As. Higher Fe and Mn concentrations and lower As concentrations were observed in M1 of the western half-lake than those in M4 of the eastern half-lake due to different sources and metal contamination levels in the two regions. Cu and Zn showed increasing concentrations similar to Mn and Fe at 1–2 cm depth of sediments, while DGT measured Co, Ni, Cd and Pb concentrations decreased down to 3–4 cm in the profiles. Co, Ni, Cu, Zn, Cd and Pb showed insignificant regional concentration variances in the western and eastern half-lakes. According to the R(C DGT/C centrifugation) values, the rank order of metal labilities decrease as follows: Fe (>1) > Cu, Pb, Zn (>0.9) > Co, Ni, Cd (>0.3) > Mn, As (>0.1).  相似文献   

4.
The Ta Nang gold deposit is localized in Middle Jurassic black shales. The ore zone is a series of layer-by-layer crush zones and zones of hydrothermal rock alteration, < 10 m in thickness and > 2 km in length. It consists of quartz-sulfide veins, sulfidized black shales, and their hydrothermally altered varieties. Sulfide mineralization occurs as two assemblages: early pyrite-arsenopyrite and late chalcopyrite-sphalerite- galena. The pyrite-arsenopyrite assemblage is composed of different morphogenetic varieties. Coarse-crystalline arsenopyrite and pyrite aggregates and metacrystals of different orientations, 0.1 to 10 mm in size, are the most widespread. The chalcopyrite-sphalerite-galena assemblage is scarce. Along with the main ore minerals, it includes more rare minerals: pyrrhotite, lead sulfosalts (tsugaruite), and gold, which form a spatial assemblage with the main minerals or small inclusions in them. Gold occurs mainly as fine dissemination in cracks in pyrite, arsenopyrite, chalcopyrite, and quartz. Gold content in sulfidized carbonaceous shales is no more than tenths of ppm, averaging 0.38 ppm. This content in the quartz veins is considerably higher, averaging 3.92 ppm. Silver contents in the shales and quartz veins are similar and equal to 2.68 and 5.30 ppm, respectively. Also, the sulfidized rocks and veins have elevated contents of Fe, As, Pb, Zn, Cu, Cd, Ni, and Co; most of these elements (Fe, As, Pb, Zn, and Cu) make up their own sulfide minerals, and the others are trace elements. According to 39Ar/40Ar dating of sericite from the quartz-sulfide veins, their age is 129.3 ± 5.6 Ma, which is close to the age of the Cretaceous granite intrusions of the Deo Ca complex. These veins formed from moderately strong solutions (11.7-6.4 wt.% NaCl equiv) with the CH4 + N2 + CO2 gas phase at 340–130 °C. Judging from the S isotope composition (534S = 1.6-4.3%c), predominantly deep-seated endogenic sulfur participated in the formation of ore sulfide associations. Analysis of the distribution of gold shows that it was deposited together with sulfide minerals (galena, sphalerite, and chalcopyrite) at a later stage.  相似文献   

5.
梅仙丁家山铅锌矿床是闽中新元古代马面山群中多个大中型铅锌多金属矿床的典型代表.本文以丁家山铅锌矿床两类矿石(含磁黄铁矿矿石和含磁铁矿矿石)内的闪锌矿和黄铁矿为研究对象,通过电子探针及LA-ICP-MS微量元素分析技术,揭示二者的微量元素组成和赋存状态,探讨成矿温度及矿床成因方面的重要信息.分析结果显示:闪锌矿内Fe、Mn、Cd、Cu、In、Pb、Bi元素较为富集,两类矿石内的闪锌矿除Fe元素含量相差较大以外(平均值分别为9.3％和1.7％),其他元素含量并无明显差异;电子探针面扫描和LA-ICP-MS剥蚀图像显示元素Mn、Cd、In以类质同象形式存在,而Fe、Cu、Pb、Bi则有类质同象和显微包体2种存在形式.黄铁矿微量元素含量整体较低,元素Co、Ni、Pb、Bi相对富集,Ni、Mn主要以类质同象形式存在,Cu、Co有类质同象替换和显微包体2种形式,Pb、Bi主要以方铅矿包体形式存在.两类矿石中的闪锌矿Zn/Cd比值分别在120～150之间和93～210之间,均指示中温成矿条件.两类闪锌矿内Fe、Cd、Mn元素含量特征与典型矽卡岩型矿床内的闪锌矿相吻合;矿床内硫化物硫同位素组成揭示成矿物质来自于岩浆岩.上述证据共同支持梅仙丁家山铅锌矿矿床属矽卡岩型矿床.  相似文献   

6.
Water, sediment, and mine spoil samples were collected within the vicinity of the Okpara coal mine in Enugu, Southeastern Nigeria, and analyzed for trace elements using ICP-MS to assess the level of environmental contamination by these elements. The results obtained show that the mine spoils and sediments are relatively enriched in Fe, with mean values of 1,307.8(mg/kg) for mine spoils and 94.15% for sediments. As, Cd, Cr, Mn,Ni, Pb, and Zn in the sediments were found to be enriched relative to the mean values obtained from the study area, showing contamination by these elements. The mean values of Fe, Mn, Cu, and Cr in the mine spoils and mean values of Fe, Cu, Pb, Zn, Ni, Cr, and Mn in sediments, respectively, are above the background values obtained from coal and shale in the study area, indicating enrichment with these elements. The water and sediments are moderately acidic, with mean pH values of 4.22?±?1.06 and 4.66?±?1.35, respectively. With the exception of Fe, Mn, and Ni, all other elements are within the Nigerian water quality standard and WHO limits for drinking water and other domestic purposes. The strong to moderate positive correlation between Fe and Cu (r?=?0.72), Fe and Zn (r?=?0.88), and Fe and As (r?=?0.60) at p?<?0.05 as obtained for the sediments depict the scavenging effect of Fe on these mobile elements. As also shows a strong positive correlation with Mn (r?=?≥ 0.70, p?<?0.05), indicating that Mn plays a major role in scavenging elements that are not co-precipitated with Fe. In water, the strong positive correlation observed between Cr and Cd (r?=?1.00), Cu and Ni (r?=?0.94), Pb and Cu (r?=?0.87) and Zn and Cu (r?=?0.99); Ni and Pb (r?=?0.83) and Zn and Ni (r?=?0.97); and between Pb and Zn (0.84) at p?<?0.05 may indicate similar element–water reaction control on the system due to similarities in chemical properties as well as a common source. Elevated levels of heavy metals in sediments relative to surface water probably imply that sorption and co-precipitation on Al and Fe oxides are more effective in the mobilization and attenuation of heavy metals in the mine area than acid-induced dissolution. The level of concentration of trace elements for the mine spoils will serve as baseline data for future reference in the study area.  相似文献   

7.
In this study, the equilibrium partitioning approach was used to derive the sediment quality criteria (SQC) recommended values of eight heavy metals (Cr, Cu, Pb, Zn, Cd, As, Fe and Mn) for surface sediments taken from Lake Chaohu. The concentration of the heavy metal in the interstitial water (C IW) was determined by the film diffusion gradient technology to obtain the metal partitioning coefficient (K P). Moreover, the metal fractionation of the sediments were analyzed using European Community Bureau of Reference sequential extraction procedure and the partitioning of bound phases including total organic carbon (TOC), grain sizes and acid volatile sulfide (AVS) were also investigated. The values of K P for Cr, Cu, Pb, Zn, Cd, As, Fe and Mn were 3,924.84, 2,276.23, 17,811.30, 738.35, 10,986.54, 718.74, 5,875.34 and 341.20 L/kg, respectively. Sediment quality criteria were normalized on the basis of fine materials, AVS, TOC and the residual metals (M R). SQC values for Cr, Cu, Pb, Zn, Cd, As, Fe and Mn based on Chinese surface water quality criteria were derived with the values of 78.53, 56.95, 362.93, 74.68, 23.90, 71.84, 3,546.53 and 68.42 mg/kg, respectively. The suggested SQC values in this study were compared SQCs from different countries and areas, which indicated SQCs from different countries or regions appeared to have great discrepancies attributed to the difference of the physical and chemical characteristics of sediments.  相似文献   

8.
Sequential digestions of Fe-Mn oxide coated boulders collected upstream and downstream from the Magruder mine, Lincoln Co., Georgia, indicate probable partitioning relationships for Zn, Cu, Pb, Co, and Ni with respect to Mn and Fe. Initial digestion with 0.1M hydroxylamine hydrochloride (Hxl) in 0.01M HNO3 selectively dissolyes Mn oxides, whereas subsequent digestion with 1:4 HCl dissolves remaining Fe oxides.The results indicate that partitioning is not constant, but varies systematically with respect to the location of metal-rich waters derived from sulfide mineralization. Upstream from the mineralized zone Zn and Ni are distinctly partitioned to the Fe oxide component and Co and Cu are partitioned to the Mn oxide component. Immediately downstream from the mineralized zone, Mn oxides become relatively more enriched in Zn, whereas Fe oxides are relatively more enriched in Cu, Co, and Ni. Analytical precision for Pb is poor, but available data suggests it is more closely associated with Fe oxides.For routine geochemical surveys utilizing coated surfaces, a one-step digestion method is probably adequate. Parameters useful for detecting sulfide mineralization are metal concentrations normalized to surface area or various ratios (e.g. Zn/(Mn + Fe), Cu/Mn, Pb/Fe). Ratios can be obtained much faster, and at lower analytical costs than conventional analysis of stream sediment.  相似文献   

9.
The concentrations of heavy metals (Cr, Co, Ni, Cu, Zn, Pb, Cd, As, Hg, and Fe) in sediments of the Yangtze River, China, were investigated to evaluate levels of contamination and their potential sources. The lowest heavy metal concentrations were found in the source regions of the river basin. Relatively high concentrations of metals, except Cr, were found in the Sichuan Basin, and the highest concentrations were in the Xiangjiang and Shun’anhe rivers. All concentrations, except Ni, were higher than global averages. Principal component analysis and hierarchical cluster analysis showed that Zn, Pb, As, Hg, and Cd were derived mainly from the exploitation of various multi-metal minerals, industrial wastewater, and domestic sewage. Cu, Co, and Fe were derived mainly from natural weathering (erosion). Cr and Ni were derived mainly from agricultural activities, municipal and industrial wastewater. Sediment pollution was assessed using the geoaccumulation index (I geo) and enrichment factor (EF). Among the ten heavy metals assessed, Cd and Pb had the highest I geo values, followed by Cu, As, Zn, and Hg. The I geo values of Fe, Cr, Co, and Ni were <0 in all sediments. EF provided similar information to I geo: no enrichment was found for Cr, Co, and Ni. Cu, Zn, As, and Hg were relatively enriched at some sites while Cd and Pb showed significant enrichment.  相似文献   

10.
As a result of LA ICP MS analysis of sulfides of the Semenov-2 hydrothermal field, it is established that covellite, which replaces Zn sulfides, is enriched in most trace elements. The Ga, Ni, and In contents in it do not vary, whereas Mn, Co, and Cd are lower than in sphalerite. The distribution of trace elements in covellite, which replaces Cu–Fe sulfides, is distinct: it is enriched in Cd, Sb, Pb, and Bi, whereas the contents of other elements are either lower or invariant. Covellite, which replaces Zn sulfides, is enriched in all trace elements relative to that replacing Cu–Fe sulfides. Enrichment of covellite in trace elements relative to primary sulfides was favored by oxidation of the hydrothermal fluid by seawater, which is similar to the processes of submarine oxidation of ancient massive sulfide deposits. Covellite is also a host to invisible gold and silver in ores of the Semenov-2 field along with toxic elements such as As, Se, Te, Tl, and Cd.  相似文献   

11.
作为华南大面积低温成矿域的重要组成部分,川滇黔铅锌矿集区是我国重要的铅锌银等资源基地之一,同时该矿集区也是Ge、Cd、Ga和In等稀散元素的超常富集区域。毛坪矿床是该矿集区内第二大铅锌矿床,累计探明铅锌金属储量超过3Mt(Pb+Zn平均品位≥18%),锗(Ge)保有储量182t。本文以新发现的Ⅵ矿带(铅锌金属已探明储量≥60万t,Pb+Zn平均品位≥20%)为研究对象,利用LA-ICPMS对主要矿石矿物闪锌矿和黄铁矿进行了微区原位微量元素组成和Mapping分析。研究结果显示Ⅵ矿带闪锌矿普遍富集Ge(最高580×10^(-6),均值81.1×10^(-6))、Cd(最高3486×10^(-6),均值1613×10^(-6))和Ga(最高190×10^(-6),均值44.4×10^(-6));黄铁矿普遍富集Mn、As、Pb、Cu、Ag和Sb。与Ⅰ和Ⅱ号矿带闪锌矿相比,Ⅵ号矿带闪锌矿更富集Ge和Ga。闪锌矿中Fe和Pb以类质同象为主,偶见黄铁矿和方铅矿显微包体;Cu、Ge、Ag和As赋存形式主要为类质同象,替代方式为Ge^(4+)+2(Cu+,Ag+,As+)↔3Zn^(2+);Cd以类质同象方式赋存为主,替代机制为Cd^(2+)↔Zn^(2+);Ga和In可能主要以类质同象方式存在。黄铁矿中Pb和Mn主要以方铅矿和碳酸盐矿物显微包体为主;Cu、As和Sb以类质同象形式存在于黄铁矿中;Ag和Zn可能以独立矿物形式赋存;Co和Ni以类质同象方式替代Fe进入黄铁矿晶格中,替代方式为Ni^(2+)+Co^(2+)↔2Fe^(2+)。毛坪矿床新发现Ⅵ矿带硫化物相比典型MVT矿床硫化物具有不同的In和Ge含量以及Cd/Fe比值,结合矿床地质特征和其他证据,表明毛坪矿床成因类型特殊,有别于经典MVT铅锌矿床,属于川滇黔型铅锌矿床。  相似文献   

12.
The possibility of using the species Silene compacta Fischer (Caryophyllaceae) as a plant indicator for Zn, Fe and Cu is discussed in this paper. Rock and plant samples were collected from an area near Essimi, north-eastern Greece, which is known for its Cu–Pb–Zn mineralization and analyzed for their content in 14 elements (Fe, Mn, Ag, As, Cd, Co, Cu, Mo, Ni, Pb, Sb, Sn, Zn and V). The data illustrate positive linear correlation between the concentrations of Zn, Fe and Cu in plant ash and rock samples. In particular, these correlations are 0.99 for Zn, 0.97 for Fe and 0.97 for Cu and are significant at the 99.9% confidence level. Therefore, S. compacta could be used as a plant indicator for Zn, Fe and Cu mineralization.  相似文献   

13.
The formation of iron sulphide minerals exerts significant control on the behaviour of trace elements in sediments. In this study, three short sediment cores, retrieved from the remote Antinioti lagoon (N. Kerkyra Island, NW Greece), are investigated concerning the solid phase composition, distribution, and partitioning of major (Al, Fe) and trace elements (Cd, Cu, Mn, Pb, and Zn). According to 210Pb, the sediments sampled correspond to depositions of the last 120 years. The high amounts of organic carbon (4.1–27.5%) result in the formation of Fe sulphides, predominantly pyrite, already at the surface sediment layers. Pyrite morphologies include monocrystals, polyframboids, and complex FeS–FeS2 aggregates. According to synchrotron-generated micro X-ray fluorescence and X-ray absorption near-edge structure spectra, authigenically formed, Mn-containing, Fe(III) oxyhydroxides (goethite type) co-exist with pyrite in the sediments studied. Microscopic techniques evidence the formation of galena, sphalerite and CuS, whereas sequential extractions show that carbonates are important hosts for Mn, Cd, and Zn. However, significant percentages of non-lattice held elements are bound to Fe/Mn oxyhydroxides that resist reductive dissolution (on average 60% of Pb, 46% of Cd, 43% of Zn and 9% of Cu). The partitioning pattern changes drastically in the deeper part of the core that is influenced by freshwater inputs. In these sediments, the post-depositional pyritization mechanism, illustrated by overgrowths of Fe monosulphides on pre-existing pyrite grains, results in relatively high degree of pyritization that reaches 49% for Cd, 66% for Cu, 32% for Zn and 7% for Pb.  相似文献   

14.
丁帅帅  郑刘根  程桦 《岩矿测试》2015,34(6):629-635
煤矸石是我国堆存量最大的工业固体废物,本文应用电感耦合等离子体发射光谱法、逐级化学提取法和相关性分析研究了淮北临涣矿区低硫煤矸石中10种微量元素的含量及赋存状态,并运用风险评价指数法评价其环境效应。结果表明,低硫煤矸石中Ba、Co、Cr、Mn、Ni、Pb、V含量均高于淮北煤和中国煤均值,Mn、V的富集系数大于1,有一定迁移风险。微量元素主要以残渣态和铁锰氧化物结合态存在,两者质量分数之和为68.87%~92.93%,其中Cd、Co、Cr、Cu、Ni、Pb、Zn赋存于硫化物矿物中,V赋存于黏土矿物中,Mn赋存于碳酸盐矿物和硫化物矿物中。10种微量元素对环境的危害性大小为:MnZnNiPbCdCuBaVCrCo,表明低硫煤矸石堆存过程中活性态Mn对生态环境造成危害的可能性最大,由Mn可能引起的煤矸石山周边地区土壤及水体污染应当重视。  相似文献   

15.
山西高凡银金矿床黄铁矿的微量元素标型特征及其应用   总被引：2，自引：0，他引：2  
高凡银金矿床黄铁矿的微量元素研究发现富Au、Ag、Pb、Zn、As、Sb,贫Co、Ni、Se,且S/Se较大,S/As和Fe/(Pb+Zn)较小,As/(Co+Ni)、(Pb+Zn)/(Co+Ni)>10。同时高凡矿田中的滩上铜钼矿化点的黄铁矿则显示相反的特征。总结出一套区分两类矿化黄铁矿微量元素的标型特征,对高凡矿田和五台地区各矿化点的判别和评价中显示了一定的适用性,可作为本区寻找同类金银矿床的找矿标型特征。  相似文献   

16.
青岛胶州湾沉积物痕量元素黄铁矿化程度及其剖面类型   总被引：4，自引：0，他引：4  
为了探索青岛近海不同沉积环境下不同痕量元素的黄铁矿化规律, 2003年5月潜水员潜入海底采集了4个不同沉积环境的未扰动柱样, 并利用Huerta-Diaz and Morse (1990)连续提取技术测试分析了沉积物痕量金属的不同存在形式(活性态和黄铁矿结合态) 在垂直剖面上的分布规律.结果表明: 除了在涨潮三角洲上部沉积和潮下带沉积物柱子的Cd和Cr外, 痕量元素的黄铁矿化度的增高取决于其相应剖面上的DOP的增高; 并且不同痕量元素向黄铁矿中转移的规模存在着较大的差别, 即元素As、Hg和Mo转移的规模最大, Cu、Zn、Cd、Cr、Co和Ni中等, Pb和Mn最小; 此外, 还进一步揭示了河流三角洲沉积物的下部各元素的黄铁矿化程度高, 而潮下带沉积物以及涨潮三角洲沉积物低.最后指出在河口水下三角洲进行的清淤工作应注意黄铁矿结合态痕量元素的活化而产生生物有效的毒性元素.   相似文献   

17.
Six epizonal gold deposits in the 30-km-long Yangshan gold belt, Gansu Province are estimated to contain more than 300 t of gold at an average grade of 4.76 g/t and thus define one of China's largest gold resources. Detailed paragenetic studies have recognized five stages of sulfide mineral precipitation in the deposits of the belt. Syngenetic/diagenetic pyrite (Py0) has a framboidal or colloform texture and is disseminated in the metasedimentary host rocks. Early hydrothermal pyrite (Py1) in quartz veins is disseminated in metasedimentary rocks and dikes and also occurs as semi-massive pyrite aggregates or bedding-parallel pyrite bands in phyllite. The main ore stage pyrite (Py2) commonly overgrows Py1 and is typically associated with main ore stage arsenopyrite (Apy2). Late ore stage pyrite (Py3), arsenopyrite (Apy3), and stibnite occur in quartz ± calcite veins or are disseminated in country rocks. Post-ore stage pyrite (Py4) occurs in quartz ± calcite veins that cut all earlier formed mineralization. Electron probe microanalyses and laser ablation-inductively coupled plasma mass spectrometry analyses reveal that different generations of sulfides have characteristic of major and trace element patterns, which can be used as a proxy for the distinct hydrothermal events. Syngenetic/diagenetic pyrite has high concentrations of As, Au, Bi, Co, Cu, Mn, Ni, Pb, Sb, and Zn. The Py0 also retains a sedimentary Co/Ni ratio, which is distinct from hydrothermal ore-related pyrite. Early hydrothermal Py1 has high contents of Ag, As, Au, Bi, Cu, Fe, Sb, and V, and it reflects elevated levels of these elements in the earliest mineralizing metamorphic fluids. The main ore stage Py2 has a very high content of As (median value of 2.96 wt%) and Au (median value of 47.5 ppm) and slightly elevated Cu, but relatively low values for other trace elements. Arsenic in the main ore stage Py2 occurs in solid solution. Late ore stage Py3, formed coevally with stibnite, contains relatively high As (median value of 1.44 wt%), Au, Fe, Mn, Mo, Sb, and Zn and low Bi, Co, Ni, and Pb. The main ore stage Apy2, compared to late ore stage arsenopyrite, is relatively enriched in As, whereas the later Apy3 has high concentrations of S, Fe, and Sb, which is consistent with element patterns in associated main and late ore stage pyrite generations. Compared with pyrite from other stages, the post-ore stage Py4 has relatively low concentrations of Fe and S, whereas As remains elevated (2.05～3.20 wt%), which could be interpreted by the substitution of As? for S in the pyrite structure. These results suggest that syngenetic/diagenetic pyrite is the main metal source for the Yangshan gold deposits where such pyrite was metamorphosed at depth below presently exposed levels. The ore-forming elements were concentrated into the hydrothermal fluids during metamorphic devolatilization, and subsequently, during extensive fluid–rock interaction at shallower levels, these elements were precipitated via widespread sulfidation during the main ore stage.  相似文献   

18.
对吉林南部地区煤矿主采煤层中的As、B、Ba、Cd、Cu、Hg、Pb、Se、Sr等微量元素的分析结果表明，太原组与山西组由于成煤环境不同，微量元素组成及含量存在一定的差异：太原组原煤中As、B、Hg、Pb、Se、Zn的含量明显高于山西组，山西组原煤中Ba、Cr、Cu、Mn、V的含量明显高于太原组。吉南煤区原煤中As、B、Hg、Pb、Se明显高于地壳元素平均值，呈富集状态，Co、Cd与地壳平均值接近，其他元素均亏损。与全国煤中微量元素相比，该区原煤中As、Ba、Co、Cr、Cu、Hg、Ni、Pb、Se、V、Zn的含量高于全国平均值，B、Mn、Sr含量低于全国平均值。微量元素赋存状态及相关分析表明，Fe与亲硫有害元素As、Cu、Hg、Pb、Se具有显著相关关系，说明煤中黄铁矿及其他硫化物是许多有害微量元素的重要载体。  相似文献   

19.
Analyses of pyrite, chalcopyrite and magnetite from the volcanic-hosted Big Cadia stratabound iron-copper deposit in Central Western New South Wales show considerable variation in the minor elements Mn, Ba, Ag, Pb, Zn, Cd, Se, Co and Ni. The preferential concentration of Co and Cd in pyrite, Zn and Ag in chalcopyrite and Mn in magnetite can be attributed to variations in activities of the ions in the hydrothermal fluid at the time of crystallisation of the mineral phases, or in cases such as the concentration of Co in pyrite, dependent on compatible electronic spin states between Co2+ and Fe2+. Trace element concentrations, especially Co and Ni contents and Co:Ni ratios in pyrite (average Co:Ni ratio=17.1) support a volcanic exhalative origin of mineralisation at Big Cadia. Differences in trace element composition such as higher Ni contents in pyrite in contrast with other volcanic-hosted ores may reflect the more basic character of volcanic rocks underlying the Big Cadia deposit.  相似文献   

20.
A halocline developed in the GotlandDeep, Baltic Sea, at c. 8.0 14C ky BP, as theresult of a transition from fresh to brackish water.The sediment-water interface changed from oxic topredominantly anoxic, depositional conditions wereperiodically euxinic and pyrite formation wasextensive. This environmental change led topyritization of the upper part of earlier depositedsediments. This study discusses how the distributionof trace elements (As, Ba, Cd, Cu, Co, Mo, Mn, Ni, Pb,U, Zn and V) were affected by the changing redoxconditions, productivity and salinity. The reducingconditions led to pyritization of Cu, Co, Ni, Cd, Mo,Mn and As. Lead and Zn concentrations are very low inpyrite, in agreement with their coordination tosulfide being tetrahedral. Certain elements areenriched in those sediments deposited under euxinicconditions. This enrichment was caused by scavengingof elements dissolved in the water column and isrestricted to elements that have a comparably longresidence time in the Baltic Sea. Molybdenum appearsto be the most unambigious proxy for euxinicconditions, whereas enrichment of U also requiresbrackish water in the productive zone. In the brackishenvironment, enrichment of Ba and V are linked to thecycling of organic carbon. Manganese and As are theonly elements that have been significantly remobiliseddue to the downward moving pyritization front.  相似文献   

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