首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献，搜索用时 968 毫秒
1.
  相似文献   

2.
The Jianchaling nickel deposit in the Bikou Terrane (Shaanxi Province, China) occurs along the boundaries between granite porphyry and carbonated ultramafic rocks (carbonated serpentinite, talc–carbonate rocks, and listwaenite). Serpentine– magnetite, serpentine– magnesite– magnetite, and magnesite– talc– quartz– pyrite– violarite– millerite– chalcopyrite assemblage formed in carbonated ultramafic rocks during hydrothermal activities. Ni-bearing sulphides, coexisting with magnesite, postdated magnetite in carbonated ultramafic rocks. Compared with serpentinite, Ni, Co, Cu, Mn, and Pb concentrate in talc–carbonate rocks. The fact that the NiO contents of magnetite decrease with progressive carbonation of serpentinite suggests that Ni from magnetite concentrated in fluid and contributed to the formation of the Jianchaling nickel deposit. Sulphides precipitated from fluid with log fO2 value varying from −34.5 to −31.8 and log fS2 value varying from −10.3 to −9.2. High pH and HS− activities triggered by transformation of serpentine into magnesite–talc–quartz assemblage promoted precipitation of Ni-bearing sulphides, and finally formed the Jianchaling hydrothermal nickel deposit.  相似文献   

3.
Lamprophyresarewidespreadinthe“Sanjiang”(tri river)alkali richintrusiverockbelt(Ailaoshan Jinshajiangalkali richintrusiverockbelt)insouth westernChinaandhaveaclosetemporalandspatialre lationwithAu,Cumineralization(HuYunzhonget al.,1995;HuangZhilongetal.,1999).Therefore,thereiscrucialsignificanceinsuchaspectsastectonic environment,mantlemetasomatism,crust mantlein teraction,magmaticevolutionandassociatedminerali zation.TheBaimazhainickeldepositislocatedinthe southernsegmentofthe“Sanjiang…  相似文献   

4.
The Shkol’noe deposit is localized in a small granitoid stock, the root portion of which is traced using geophysical data to a depth of 5–8 km. The high-grade gold ore (33 gpt Au) is enriched in silver and principally differs in ore composition from the previously studied mesothermal gold-quartz and epithermal gold-silver deposits in the Russian Northeast. The main reserves of the Shkol’noe deposit concentrate in bonanzas (20% of the total volume of orebodies). The internal deformation is related to the rearrangement of matter in freibergite; exsolution structures in fahlore and native gold are related to postmineral metamorphism. It is suggested that the ore of the Shkol’noe deposit occupies a transitional position between porphyrytype and epithermal levels of ore deposition.  相似文献   

5.
  相似文献   

6.
Series of sedimentary hydrothermal-diplogenetic copper deposits have been found scattering in the region along the middle-lower reaches of the Yangtze River, and their metallogenetic mechanism is still in hot debate. In order to reveal the ore-forming kinetics of sedimentary process and hydrothermal superimposition, and evaluate the role of sedimentary pyrite in the enrichment and precipitation of copper, a set of simulating experiments on the reaction between pyrite and CuCl2 solution were conducted. According to the physicochemical characteristics of the ore-forming fluid of the Dongguashan copper deposit, Anhui Province, 100 MPa was selected as the experimental pressure, and the experimental temperatures were set at 450, 350, 250 and 150°C, respectively. The reactions between pyrite grains isolated from the Shimenkou strata-bound pyrite deposit and the solution with 0.2 mol/L CuCl2 and 1.0 mol/L NaCl were experimentally simulated. Then, variations in surface topography and surface chemistry of the experimental pyrite grains were documented using scanning electronic microscopy (SEM), atomic force microscopy (AFM), Auger electron spectrometry (AES) and X-ray photoelectron spectroscopy (XPS), and the solution and newly formed minerals were analyzed using inductively coupled plasma (ICP-AES) and X-ray diffraction (XRD) techniques. Desulphurization of pyrite surface was observed and new copper minerals were detected. It is proposed that pyrite can act as a geochemical barrier for the enrichment and precipitation of copper from the solution under the experimental conditions. Furthermore, the ore-forming mechanism of sedimentary hydrothermal-diplogenetic copper deposits was discussed.  相似文献   

7.
《Ore Geology Reviews》2003,22(1-2):61-90
Quantitative laser ablation (LA)-ICP-MS analyses of fluid inclusions, trace element chemistry of sulfides, stable isotope (S), and Pb isotopes have been used to discriminate the formation of two contrasting mineralization styles and to evaluate the origin of the Cu and Au at Mt Morgan.The Mt Morgan Au–Cu deposit is hosted by Devonian felsic volcanic rocks that have been intruded by multiple phases of the Mt Morgan Tonalite, a low-K, low-Al2O3 tonalite–trondhjemite–dacite (TTD) complex. An early, barren massive sulfide mineralization with stringer veins is conforming to VHMS sub-seafloor replacement processes, whereas the high-grade Au–Cu ore is associated with a later quartz–chalcopyrite–pyrite stockwork mineralization that is related to intrusive phases of the Tonalite complex. LA-ICP-MS fluid inclusion analyses reveal high As (avg. 8850 ppm) and Sb (avg. 140 ppm) for the Au–Cu mineralization and 5 to 10 times higher Cu concentration than in the fluids associated with the massive pyrite mineralization. Overall, the hydrothermal system of Mt Morgan is characterized by low average fluid salinities in both mineralization styles (45–80% seawater salinity) and temperatures of 210 to 270 °C estimated from fluid inclusions. Laser Raman Spectroscopic analysis indicates a consistent and uniform array of CO2-bearing fluids. Comparison with active submarine hydrothermal vents shows an enrichment of the Mt Morgan fluids in base metals. Therefore, a seawater-dominated fluid is assumed for the barren massive sulfide mineralization, whereas magmatic volatile contributions are implied for the intrusive related mineralization. Condensation of magmatic vapor into a seawater-dominated environment explains the CO2 occurrence, the low salinities, and the enriched base and precious metal fluid composition that is associated with the Au–Cu mineralization. The sulfur isotope signature of pyrite and chalcopyrite is composed of fractionated Devonian seawater and oxidized magmatic fluids or remobilized sulfur from existing sulfides. Pb isotopes indicate that Au and Cu originated from the Mt Morgan intrusions and a particular volcanic strata that shows elevated Cu background.  相似文献   

8.
The Zijinshan high-sulfidation epithermal Cu–Au deposit is located in the Zijinshan ore field of South China, comprising porphyry–epithermal Cu–Au–Mo–Ag ore systems. The Cu ore body is more than 1000 m thick and is characterized by an assemblage of digenite–covellite–enargite–alunite. Digenite is the dominant Cu-bearing mineral, which makes this deposit unique, although the mechanisms of digenite formation remain controversial. To elucidate the genesis of digenite, this paper presents the Cu isotopic compositions of Cu-sulfides in the Zijinshan high-sulfidation Cu–Au deposit. The Cu isotopic values (65Cu relative to NIST 976) of all samples range from −2.97‰ to +0.34‰, and most values fall in a narrow range from −0.49‰ to +0.34‰, which is similar to the Cu isotopic signature of typical porphyry systems. Copper isotope ratios of each mineral decrease with increasing depth, a trend that is also typical of porphyry deposits. The variation tendency of δ65Cu values between sulfides is consistent with the sequence of mineral formation. These observations suggest that the Cu-sulfides in the Zijinshan Cu–Au deposit have a hypogene origin.  相似文献   

9.
The paper reports the mineralogical and geochemical features of the Kysylga gold deposit located in the hornfelsed Norian sedimentary rocks and classified with low-sulfide gold–quartz type of deposits typical of the Verkhoyansk–Kolyma metallogenic province. Detailed typomorphic study of the major minerals (quartz, arsenopyrite, and gold) of the ore veins shows that the deposit is assigned to the gold–silver type. Mineralogical and geochemical data substantiate this conclusion.  相似文献   

10.
Placer gold particles derived from epithermal deposits display distinct morphological and compositional features compared with particles from mesothermal systems. Here, it is hypothesized that the chemical composition of primary gold derived from different deposit types is a principle factor affecting the composition of resident biofilm communities as well as the transformation of placer particles. Gold particles were collected from placers originating from the epithermal system at the Eisenberg, Germany's largest primary gold deposit. For comparison, placer gold from mesothermal sources was studied. Morphological differences due to mechanical transport and physical reshaping were not observed. Biogeochemical gold/silver dissolution and gold re-precipitation were evident on epithermal particles and they accentuate the silver-fabrics and gold-rich clusters. In contrast, on mesothermally derived gold particles these processes led to the development of gold-rich rims via the formation of nano-porous secondary gold. Microprobe- and laser ablation mass spectrometric analyses of polished whole particle mounts confirmed differences in gold/silver content/distribution and trace metal content between particles from epi- and mesothermal sources, respectively. On particles from all sites nano- and micro-particulate gold is associated with polymorphic layers. These are composed of microbial cells, extracellular polymeric substances (EPS) and clay-sized minerals. Multivariate statistical analyses shows a significant difference between biofilm communities from epi- vs. mesothermally derived particles, which is linked to the chemical composition of the primary gold. While a number of key-species capable of gold transformation, e.g., Cupriavidus sp., Geobacter sp. and Rhodoferax sp., were detected on particles from both sources, higher numbers of organisms with the potential for gold solubilization, precipitation and detoxification were associated with particles from the epithermal sources. A range of species involved in gold transformation, i.e., Arthrobacter spp., Delftia sp., Shewanella sp., and Stenotrophomonas spp., were detected only on epithermally derived placer gold. This indicates the communities are sensitive to differences in gold/silver and possibly trace metal-cycling, resulting from differences in their content, distribution and mobilization behaviour in epi- vs. mesothermally derived particles. Ultimately, this study shows that the chemical composition of the primary deposit strongly influences the biogeochemical transformation of placer gold and the composition of associated biofilms, whereas physical transformations appear to be largely unaffected.  相似文献   

11.
1 Introduction Alunite [KAl3(SO4)2(OH)6] is a very important non-ferrous metal resource, so many countries throughout the world have made great investments in research on the mechanism of its formation, its geological characteristics and applications. O…  相似文献   

12.
The Zhaima gold–sulfide deposit is located in the northwestern part of the West Kalba gold belt in eastern Kazakhstan. The mineralization is hosted in Lower Carboniferous volcanic and carbonate rocks formed under conditions of marginal-sea and island-arc volcanic activity. The paper considers the mineralogy and geochemistry of primary gold–sulfide ore and Au-bearing weathering crusts. Au-bearing arsenopyrite–pyrite mineralization formed during only one productive stage. Disseminated, stringer–disseminated, and massive rocks are enriched in Ti, Cr, V, Cu, and Ni, which correspond to the mafic profile of basement. The main ores minerals are represented by finely acicular arsenopyrite containing Au (up to few tens of ppm) and cubic and pentagonal dodecahedral pyrite with sporadic submicroscopic inclusions of native gold. The sulfur isotopic composition of sulfides is close to that of the meteoritic standard (δ34S =–0.2 to +0.2). The 40Ar/39Ar age of three sericite samples from ore veinlets corresponds to the Early Permian: 279 ± 3.3, 275.6 ± 2.9, and 272.2 ± 2.9 Ma. The mantle source of sulfur, ore geochemistry, and spatial compatibility of mineralization with basic dikes allow us to speak about the existence of deep fluid–magmatic systems apparently conjugate with the Tarim plume.  相似文献   

13.
近来南岭地区加里东期钨锡找矿勘查取得较大突破,但其成因机制研究仍相对缺乏。湘西南苗儿山岩体西北部的落家冲矿床是近年新发现的加里东期钨锡矿床,具有良好的钨锡多金属矿找矿前景,其成矿流体的特征和成矿机制有待查明。在详细的野外地质调查基础上,落家冲矿床的成矿过程可划分为四个阶段:蚀变花岗岩-白钨矿阶段(Ⅰ)、云英岩-白钨矿-锡石阶段(Ⅱ)、石英脉-白钨矿阶段(Ⅲ)和石英脉-硫化物阶段(Ⅳ)。本文选取第Ⅰ阶段的锆石和锡石开展了U-Pb定年和锆石Hf同位素分析,对四个成矿阶段的石英矿物进行了流体包裹体以及H-O同位素的研究。获得的锡石U-Pb反等时线年龄(433.0±11Ma)与蚀变花岗岩锆石U-Pb年龄(430.7±2.3Ma)在误差范围内一致,表明矿区的成岩成矿作用均发生于加里东晚期。流体包裹体研究显示第Ⅰ阶段到第Ⅳ阶段,均一温度分别集中在260-380℃、260-320℃、200-320℃和180-220℃之间,呈逐渐降低的趋势,盐度则表现为由第Ⅰ阶段到第Ⅱ阶段陡降,第Ⅱ阶段到第Ⅳ阶段总体变化不大的特点(平均值分别为16.9%、3.9%、4.8%和3.7%NaCleqv)。成岩成矿定年结果、各成矿阶段的成矿流体特征,结合锆石εHf(t)=-7.6--5.0、tDM2=1565-1711Ma,和石英矿物的δ18OH_(2)O值从第Ⅰ阶段(3.97‰-5.34‰)到第Ⅳ阶段(-4.99‰--5.10‰)逐渐降低的特点,以及区域岩体的地球化学特征,本文认为落家冲钨锡矿床是加里东期起源于元古宙地壳重熔的岩浆在经历了高分异演化作用后,流体的沸腾作用以及温度下降造成成矿流体中钨锡等矿质的沉淀所形成。  相似文献   

14.
  相似文献   

15.
TheHuizelarge sizedPb ZndepositinYunnan ProvinceislocatedinthecenteroftheSichuan Yun nan GuizhouPb Zn Agpolymetalmineralizationzone(SYGPb ZnMMD)inwesternYangtzePlateandis oneofthefamousPb Zn GebasesinChina(Wang Jiangzhenetal.,2003;WangXiaochunetal.,2000).Thisdeposit,whichischaracterizedbylarge scale(Pb+Znmetallicreservesarehigherthan5mil liontons),highPb+Zngrade(thePb+Zngradesof mostoresare25%-35%),highabundanceofuseful associatedelements(Ag,Ge,Cd,Ga,etc.)and someimportantbreakt…  相似文献   

16.
  相似文献   

17.
The Zarshuran arsenic deposit has been exploited for more than one thousand years. During this period of time, trace element pollutants have been transported downstream via natural agents, however this process has been exacerbated by human interferences, such as mining activities, especially in recent years. Geochemical study of metallic contaminants revealed a high concentration of elements especially of As, Sb, Hg, and TI in ore, waste piles, water and stream sediments, so that the arsenic concentration ranges between 40-0.028 mg/L in water samples of the Zarshuran Stream. In order to investigate the mechanism of contaminant transport downstream the mine, the concentrations of arsenic and other trace elements detected in ore-waste assemblage were measured in water samples taken from 11 stations. Also, the pH and Eh values have been measured in the same waster samples. The arsenic ore mainly consists of orpiment and realgar, associated with a small amount of Sb, Hg, Tl, minerals. Weathering of this assemblage gives rise to a mine water having an arsenic concentration of 22 mg/L. As concentrations are reduced to 4.272, 3.069, 0.421, 0.083, and 0.036 mg/L at distances of about 1, 1.3, 3.3, 7 and 15.2 km down the mine, respectively. The water samples have been passed through the 0.45μ filters to determine the fraction of contaminants transported in dissolved phase and also in particulate phase. The geochemical study of contaminant transport indicates that contaminants are transported mainly as colloidal and particulate phases in the upstream and only 13% of arsenic is transported as the dissolved phase. The milky appearance of stream is evidence for colloidal transport. From 6 km downward the mine, particulate phase is not the significant carrier of contaminants and more than 90% of the arsenic is transported as dissolved phase. The very positive correlation between trace element concentrations and Fe, colloidal deposition evidence as an ocher-colored precipitate on stream bed sediments accompanied by a decrease in contaminant concentrations in stream water, the physicochemical （Eh and pH） conditions, near neutral pH values, considerable difference in concentration of Fe in dissolved and total phases, weathering of iron sulfides in the ore-waste assemblage, XRD analysis of precipitates, indicate strongly that HFO is the main carrier and transporting agent in this area.  相似文献   

18.
The Zarshuran arsenic deposit has been exploited for more than one thousand years. During this period of time, trace element pollutants have been transported downstream via natural agents, however this process has been exacerbated by human interferences, …  相似文献   

19.
The ore body “T” is the newly discovered massive-pyrite type one which is located in the central part of the Bor copper mine. The main copper minerals are chalcocite-digenite, covellite and enargite. Small amounts of colusite are frequently present in the ore-body. It mostly occurs as the distinct exsolutions in digenite and, associating with enargite and covellite. Composition of the studied colusite shows enriched Sn content, giving an empirical formula from Cu24.7V1.8Fe0.2As5.1Sb0.2Sn0.8S32 to Cu26.7V2.0Fe0.3As3.0Sb0.3Sn3.5S32. This colusite represents a solid solution between colusite and nekrasovite within a range of 14–54 mol % nekrasovite. Most of the analyses show content of <50 mol % nekrasovite corresponding to the Sn-bearing colusite variety, while one analysis shows content of 54 mol % nekrasovite corresponding to the As-bearing nekrasovite.  相似文献   

20.
The Dajing Cu-Sn-polymetallic ore deposit is famous for its large scale, abundant associated elements, narrow and closely-spaced development of ore veins and high grade, but exploration within the mining district and its deeper parts has revealed no Yanshanian rockbody. Therefore, there have been proposed a diversity of hypotheses on the genesis of the deposit. The authors, from the angle of mantle-branch structure, provided evidence showing that the mining district is located in the core of the Da Hinggan Ling mantle-branch structure, the multi-stage evolution of mantle plume paved the way for the ascending of deep-source ore fluids and these fluids extracted part of the ore-forming materials. Then, these ore-forming materials were concentrated in the favorable structural loci (e.g. structural fissures) to form ores. The orientation of ore-forming and ore-controlling fissures is closely related to the regionally structural stress field at the metallogenic stage. The zonation of Sn, Cu, Au, Ag, Pb, and Zn within the mining district appears to be related to metallogenesis and the crystallization temperature of ore-forming materials. Mineralization of Sn, Cu, Au, etc. which require relatively high crystallization temperature and pressure is in most cases recognized in the central part of the mining district, while that of Ag, Pb, Zn, etc. which require relatively low crystallization temperature and pressure is, for the most part, produced in the periphery of the mining district.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号