云南易门狮子山铜矿床黄铜矿-斑铜矿Re-Os定年与S同位素组成

易门狮子山铜矿床是康滇地区元古宙昆阳裂谷中的典型铜矿床之一,受狮子山背斜北西翼次级构造控制明显,矿石以脉状、浸染状、块状为主,少量呈层纹状.为厘定构造改造成矿时代,开展与石英、方解石脉共生的富黄铜矿、斑铜矿脉岩相学研究,挑选黄铜矿、斑铜矿单矿物,进行高精度的Re-Os同位素定年测试,获得了三组模式年龄,从早到晚依次为:...     

Pyrite and oxidized iron mineral phases formed from pyrite oxidation in salt marsh and estuarine sediments

We used scanning electron microscopy and energy dispersive X-ray analysis to examine sediments from vegetated portions of three salt marshes, the Great Sippewissett Marsh (Cape Cod, MA), Sapelo Island (Georgia), and the Hackensack Meadowlands (N.J.), and from the sediments of an estuary, Newark Bay (N.J.). Pyrite particles were abundant in sediments from all sites. Both fine grained pyrite crystals and framboids were found. Single, fine grained crystals (diameter = 0.2 to 2.0 micrometers) predominated in all samples, strong evidence for rapid formation of pyrite.We also found both microcrystalline and framboidal iron-oxyhydroxide phases in many of the sediment samples. This is evidence of pyrite oxidation within the sediments and suggests that iron is conserved in salt marshes even as pyrite is oxidized. The thermodynamic stability of iron phases in marsh sediments, and recent pyrite oxidation studies in coal, suggest goethite as the crystalline iron-oxyhydroxide phase present. In addition, we sometimes found a red amorphous coating on grass roots from the Great Sippewissett and Sapelo Island marshes. This coating is likely a form of hydrated iron (III) oxide.     

Factors controlling copper solubility and chalcopyrite deposition in the Sungun porphyry copper deposit, Iran

The Sungun porphyry copper deposit is hosted in a Diorite/granodioritic to quartz-monzonitic stock that intruded Eocene volcanosedimentary and Cretaceous carbonate rocks. Copper mineralization is associated mainly with potassic alteration and to a lesser extent with sericitic alteration. Based on previously published fluid inclusion and isotopic data by Hezarkhani and Williams-Jones most of the copper is interpreted to have deposited during the waning stages of orthomagmatic hydrothermal activity at temperatures of 400 to 300 °C. These data also indicate that the hydrothermal system involved meteoric waters, and boiled extensively. In this work, thermodynamic data are used to delineate the stability fields of alteration and ore assemblages as a function of fS₂, fO₂ and pH. The solubility of chalcopyrite was evaluated in this range of conditions using recently published experimental data. During early potassic alteration (>450 °C), Copper solubility is calculated to have been >50 000 ppm, whereas the copper content of the initial fluid responsible for ore deposition is estimated, from fluid inclusion data, to have been 1200–3800 ppm. This indicates that initially the fluid was highly undersaturated with respect to chalcopyrite, which agrees with the observation that veins formed at T > 400 °C contain molybdenite but rarely chalcopyrite. Copper solubility drops rapidly with decreasing temperature, and at 400 °C is approximately 1000 ppm, within the range estimated from fluid inclusion data, whereas at 350 °C it is only 25 ppm. These calculations are consistent with observations that the bulk of the chalcopyrite deposited at Sungun is hosted by veins formed at temperatures of 360 ± 60 °C. Other factors that, in principle, may reduce chalcopyrite solubility are increases in pH, and decreases in fO₂ and aCl⁻. Our analysis shows, however, that most of the change in pH occurred at high temperature when chalcopyrite was grossly undersaturated in the fluid, and that the direction of change in fO₂ increased chalcopyrite solubility. We propose that the Sungun deposit formed mainly in response to the sharp temperature decrease that accompanied boiling, and partly as a result of the additional heat loss and decrease in aCl⁻, which occurred as a result of mixing of acidic Cu-bearing magmatic waters with cooler meteoric waters of lower salinity. Received: 8 July 1998 / Accepted: 8 April 1999     

ToF-SIMS and SEM study on the preferential oxidation of chalcopyrite

Chalcopyrite is known to be slow reacting mineral in hydrometallurgical systems and is considered one of the most inert sulphide minerals with respect to leaching. Such character of chalcopyrite seems to be linked to a formation of a passive layer on its surface. This work reports that freshly fractured chalcopyrite surfaces exhibit highly selective reactivity depending on the exposed fracture planes. ToF-SIMS was used to qualitatively characterize various fracture planes in freshly fractured chalcopyrite particles, prior to and after hydrometallurgical treatment. It was found that, prior to treatment, certain areas exhibited pronounced contamination from atmospheric hydrocarbons; whereas, others were highly unreactive and remarkably free from adventitious hydrocarbon contamination. The positive ion spectra recorded from these areas were found to be dominated by peaks from Fe- and Cu-elements and related compounds. The negative ion spectra for the reactive areas on the other hand showed a high content of oxidized (sulphur) species.The differences between the areas of low and high reactivity, as detected after leaching, were more subtle than prior to leaching; whereas, SEM analysis showed clear evidence for selective attack of ferric sulphate to specific planes. Furthermore, it was shown that, when chalcopyrite is in intimate contact with pyrite, it experiences an enhanced oxidation compared to when there is no electric contact with pyrite.Attempts were made to explain the preferential oxidation observed based on the different chemistry of the fracture surfaces.     

Variation of copper isotopes in chalcopyrite from Dabu porphyry Cu-Mo deposit in Tibet and implications for mineral exploration

The study presents copper (Cu) isotope data of mineral separates of chalcopyrite from four drill core samples in the Miocene Dabu porphyry Cu-Mo deposit formed in a post-collisional setting in the Gangdese porphyry copper belt, southern Tibet. Copper isotope values in hypogene chalcopyrite range from –1.48‰ to +1.12‰, displaying a large variation of up to 2.60‰, which demonstrates Cu isotope fractionation at high-temperature during hydrothermal evolution. The majority of measured chalcopyrite isotopic compositions show a gradual increasing trend from –1.48‰ to +1.12‰ with the increase of drilling depth from 130m to 483m, as the alteration assemblages change from potassic to phyllic. Similarly, the other δ⁶⁵Cu values (δ⁶⁵Cu = ((⁶⁵Cu/⁶³Cu)_sample/(⁶⁵Cu/⁶³Cu)_standard − 1) × 1000) of the chalcopyrite show a gradual increasing trend from −1.48‰ to +0.59‰ with the decrease of drilling depth from 130 m to 57 m, as the alteration assemblages change from potassic, phyllic, through argillic to relatively fresh. These observations suggest a genetic link between Cu isotope variation and silicate alteration assemblages formed at different temperatures, indicative of a Rayleigh precipitation process resulting in the large variation of δ⁶⁵Cu values at Dabu. In general, samples closest to the center of hydrothermal system dominated by high-temperature potassic alteration are isotopically lighter, whereas samples dominated by low-temperature phyllic alteration peripheral to the center are isotopically heavier. The predicted flow pathways of hydrothermal fluids are from No. 0 to No. 3 exploration line, and the lightest δ⁶⁵Cu values are the most proximal to the hydrothermal source. Finally, we propose that the northwest side of the No. 0 exploration line has high potential for hosting undiscovered orebodies. The pattern of Cu isotope variation in conjunction with the features of silicate alteration in porphyry system can be used to trace the hydrothermal flow direction and to guide mineral exploration.     

主要铁氧化物催化H2O2 氧化地下水中硝基苯实验

实验研究了含水层介质中主要铁氧化物催化H2O2 氧化地下水中硝基苯的机理和主要影响因素,为硝基苯污染地下水的原位化学修复技术提供了一定的理论依据。实验模拟在地下环境温度8 ℃ ～ 10 ℃条件下,利用动力学方程对硝基苯的衰减进行拟合,结果表明,其衰减系数K = 0. 044 3 min － 1 ; 硝基苯与H2O2 的最佳摩尔比为1∶200; 主要铁氧化物催化H2O2 氧化硝基苯能力依次为: 磁铁矿＞ 针铁矿＞ 氢氧化铁＞ 赤铁矿。     

新疆雅满苏铁矿床地空高光谱异常特征及应用

正雅满苏铁矿床位处东天山成矿带,成矿地质条件优越。前人在矿床的成矿规律、地球化学、矿床类型、流体来源等方面,开展了较多科研工作(李厚民等,2014;王兴保,2005)。但在遥感地质方面的研究和应用工作还未开展。铁矿床及外围区域属准平原状丘陵地貌,基岩出露,地表蚀变信息丰富,可获取高质量的地空高光谱遥感数据,有利于发挥高光谱遥感的技术优势。     

Effect of oxidation potential and zinc sulphate on the separation of chalcopyrite from pyrite

The effects of oxidation potential (Eh) and zinc sulphate on the separation of chalcopyrite from pyrite were investigated at pH 9.0. The flotation recovery of these minerals is Eh dependent with maximum separation obtained at 275 mV SHE. Zinc sulphate addition improved this mineral separation at an Eh value of 275 mV by selectively depressing pyrite flotation. A different result was obtained at lower Eh values where zinc sulphate addition improved chalcopyrite flotation but had no or little effect on pyrite flotation. These opposite effects of zinc sulphate on mineral flotation were reconciled by examining the surface species of these minerals. The selective depression of pyrite flotation by zinc sulphate was also confirmed in the flotation of two copper ores.     

The distribution of divalent trace elements between sulfides,oxides, silicates and hydrothermal solutions: I. Thermodynamic basis

Experimental data for the standard Gibbs free energies of formation from the elements of a wide variety of metal sulfides and oxides, spinels, olivines and pyroxenes at 25°C and 1 bar define linear correlations, within about ±900 cal·mole^?1, with the corresponding conventional standard partial molal Gibbs free energies of formation of the aqueous M²⁺ cations of the form where a_MaZ and b_MaZ are empirically determined constants characteristic of the structure M_nZ. The only exceptions to correlations of this type are compounds of the heavy alkaline earths Ca, Sr and Ba, which appear to follow correlations with cation radius instead. The linear free energy correlations enable prediction of standard Gibbs free energies of formation of compositional end-members of a particular structure M_nZ provided that a_MaZ and b_MaZ are known accurately. When only the free energy of the Mg end-member is known, the standard Gibbs free energy of formation at 25°C and 1 bar of the Fe endmember, and hence a_MaZ and b_MaZ Can be predicted from the temperature independence of and estimated entropies and heat capacities for the Fe end-member. Using this approach, the free energies of ferrosilite, hedenbergite and annite at 25°C and 1 bar were predicted to within ±1000 cal·mole^?1 of the helgesonet al. (1978) values. Free energies of formation of talc (M₃Si₄O₁₀(OH)₂), clinchlore (M₅Al₂Si₃O₁₀(OH)₈), and tremolite (Ca₂M₅(Si₄O₁₁)₂(OH)₂)-type compounds where M is Mg, Mn, Zn, Fe, Co, or Ni were then predicted at 25°C and 1 bar.Calculation of the equilibrium distribution of Mg, Zn and Sr between galena and hydrothermal solution, and Zn, Mg, Fe and Mn between chlorite and hydrothermal solution demonstrates: (1) that the Sr contents of low temperature galenas (e.g. Mississippi Valley-type) should be negligible (reported analyses of Sr content and Sr isotopic composition of such galenas are probably attributable to fluid inclusions or carbonate inclusions); and (2), that the Zn contents of hydrothermal chlorites in a model of the midoceanic ridge hydrothermal systems are sensitive to temperature, to complexing in the aqueous phase, and to the overall Fe/Mg ratio of the chlorite.     

浅谈紫金山铜矿区蓝辉铜矿及其他铜硫化物特征

紫金山铜矿区的蓝辉铜矿成因一直存有争论,其关键点在于对次生成因或原生成因的认识。文章对铜矿石光片进行反光显微镜观察,总结了铜矿物的生成顺序及分布特点,并讨论前人对蓝辉铜矿成因研究的不同成果,提出自己的一点研究看法。     

A.ferrooxidans培养过程中Al/Fe(摩尔比)对铁矿物形成产物的影响

主要研究了磷酸铝(Al PO4)的加入量对氧化亚铁硫杆菌HX3培养液中铁矿物形成的影响,并对相应沉淀产物进行了结构表征分析。结果表明,Al PO4的加入对细菌培养过程中Fe2+的氧化无明显影响,但可促进Fe3+的水解和初始铁矿物相的形成,也可加速黄钾铁矾的转化形成。Al/Fe(摩尔比)为0. 04～1的培养液中主要形成产物为施威特曼石和黄钾铁矾; Al/Fe为0. 4和1时另有磷酸铁矿形成。较高的Al/Fe比值和磷酸根含量有利于磷酸铁矿的形成。     

来自蛇绿岩地幔的硫（砷）化物矿物组合

近来在西藏雅鲁藏布江蛇绿岩带的罗布莎蛇绿岩块的地幔豆荚状铬铁矿中发现一个包括金刚石、柯石英、自然元素、合金、氧化物以及硫(砷)化物组成的地幔矿物群。该矿物群的硫(砷)化物具有特殊化学成分并呈包裹体分布在贱金属(BM)和铂族元素(PGE)或它们的合金中,大量化学成分分析得知它们主要由下列元素组成:S、As、Te、Fe、Ni、Co、Cu、Pt、Pd、Ru、Rh、Os、Ir、Mn和Ti。根据化学成分可辨别出约30种硫(砷)化物矿物:FeS、NiS、(Ni,Fe)S、Fe3S2、Ni3S2、(Ru,Os,Ir)S2、Rh7As3、Rh5Ni(Cu)As4、Pd4Rh3As3、Pd8As2、Pd3TeAs、Pd7Te3、RuAs、PtAs2、Ni4Rh3As3、Rh(As,S)2、(Rh,Ir)(As,S)2、Ir(As,S)2、MnS、Ti7S3、Ti7N3、Rh3.5Se3.5CuS2、RhS、Ir2S3、(Ir,Cu)2、S3(Co,Ni,Fe)2(As,S)3、(Ir,Pt)(As,S)2、Ru3(As,S)7以及(BM)x(PGE)yS10-(x y)等,其中包括已定名和未定名的矿物。由于矿物粒度小(<25μm),缺乏X射线分析资料,有待进一步研究。     

Amorphous copper and zinc sulfides in the metalliferous sediments of the Red Sea

Detailed studies on the copper and zinc distribution in metalliferous sediments from the Atlantis II Deep (Red Sea) demonstrate that beside chalcopyrite and sphalerite appreciable amounts of copper and zinc are found in X-ray amorphous copper and zinc sulfides not previously described. Only low contents of copper and zinc are present in nontronites, hydroxides and carbonates.     

The effects of temperature,pressure, and oxygen on copper and iron sulphides synthesised in aqueous solution

Experiments with both iron sulphide and copper sulphide precipitates in aqueous solution show that oxygen is significant in determining the mineral phases resulting after heating up to 180 °C. Tetragonal FeS converts to FeS₂ and Fe₃O₄ in the presence of oxygen, while in the absence of oxygen under the same conditions it converts to hexagonal FeS. Suspensions of covellite and of chalcocite under the same conditions convert to digenite in the presence of oxygen, but remain unchanged when oxygen is absent. Experimental evidence is advanced to support structure determinations that CuS contains disulphide ions.

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Zusammenfassung Experimente mit in wässrigen Lösungen ausgefällten Eisen- und Kupfersulfiden dokumentieren die außerordentliche Bedeutung des Sauerstoffes auf die Bildungs- und Verhaltensweise von Mineralphasen, beobachtet nach dem Aufheizen auf 180 °C. So bildet sich aus ursprünglich tetragonalem FeS letzten Endes Pyrit und Magnetit, wenn Sauerstoff zugegen war, während bei dessen Abwesenheit, aber sonst gleichen Versuchsbedingungen, die Umwandlung in hexagonales FeS erfolgte. Suspensionen von Covellin und Chalkosin wurden, unter analogen Versuchsbedingungen und in Gegenwart von Sauerstoff, in Digenit überführt, während sonst, wenn keine Sauerstoffeinwirkung stattfand, die Mineralphasen keinerlei Veränderungen erkennen ließen. Mittels solcher experimenteller Methoden lassen sich bei der Strukturbestimmung des CuS offenbar Merkmale des Vorhandenseins von Disulfidionen erkennen.

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Published by permission of the Director, Bureau of Mineral Resources, Canberra A. C. T., Australia.

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Temporary Address: Mineralog.-Petrograph. Inst. Univ. Heidelberg, Berliner Str. 19, 69 Heidelberg, Germany     

The Paleoclimatic Variation Records of Carbonate and Iron Oxides in the Weinan Loess Section

The contents and distributions of CaCO3,Fe2O3.FeO and free Fe2O3 in the Weinan loess section of Shaanxi Province of China were investigated through dense sampling.The results show that the contents of CaCO3 and the ration of Fe2O3/FeO may be chosen as proxy in dices for the precipitation and temperature changes in the formation time of the strata,respectively.According to these geochemical indices,six stages of plaeoclimate evolution are proposed in this region since 142 ka B.P.,and secondary climate changes are discussed as well based on the curves of geochemical indices.     

Isotopic composition of zinc, copper, and iron in lunar samples

We determined by ICP-MS the concentrations and isotopic ratios of Fe, Cu, and Zn in the Ti-rich lunar basalt 74275, in the lunar orange glass 74220, and in up to 10 lunar soils, namely, 14163, 15231, 64501, 66041, 68841, 69941, 70011, 72501, 75081, and 76501. Two analyses of zinc in lunar basalt 74275 give δ⁶⁶Zn = 0.17‰ and 0.75‰, values within the range of those measured in terrestrial basalts; copper in lunar basalt 74275 has δ⁶⁵Cu  +1.4‰, which is isotopically heavier than values observed in terrestrial basalts. In the orange glass, we measured δ⁵⁶Fe = −0.24‰, δ⁶⁵Cu = −0.42‰, and δ⁶⁶Zn  −3.6‰. These values of δ are more negative than those obtained for 74275 and for typical lunar basalts, but for Cu, comparable to those observed in terrestrial sulfides and meteorites. In lunar soils we found 0.11‰  δ⁵⁶Fe  0.51‰, 2.6‰  δ⁶⁵Cu  4.5‰, and 2.2‰  δ⁶⁶Zn  6.4‰. Insofar as we can generalize from a small sample set, S, Fe, Cu, Zn, and Cd show similar trends in isotopic fractionation on the Moon. Lunar basalts have nearly terrestrial isotopic ratios. Relative to the lunar basalt 74275, the pyroclastic glass 74220 is enriched in the lighter isotopes of Fe, Cu, and Zn, and the soils are enriched in the heavier isotopes of Fe, Cu, and Zn. The patterns in the basalts are likely inherited from the source material; the light-isotope enrichments seen in the orange glass originated during lava fountaining or, less probably, during partial condensation of vapor; and the heavy-isotope enrichments in the lunar soils were likely created by a combination of processes that included micrometeorite vaporization and sputtering. In the orange glass, the light-isotope enrichments (relative to lunar basalts) of Zn are larger than those of Cu. If these enrichments reflect accurately the isotopic composition of the gas, they suggest that Cu is more volatile than Zn in the liquid from which the gas derived. A simple model built on the known flux of micrometeorites to the lunar surface and a published estimate that micrometeorites generate 10 times their own mass of vapor, predicts heavy-isotope enrichments comparable to those observed in soils but only if the regolith gardening rate is set at about one twentieth of the generally accepted value of 1 cm/My. This discrepancy may reflect the difference in the time constants for micrometeorite milling and decimeter-scale gardening, or the importance of sputtering.     

新疆巴仑台铁铜矿床地质特征与成矿作用探讨

新疆巴仑台铁铜矿赋存于华力西期中酸性侵入岩与碳酸盐的接触带上,矿体形态以似层状、透镜状为主。围岩蚀变主要有矽卡岩化、绿泥石化、绿帘石化、硅化。矿石矿物以磁铁矿、黄铁矿、黄铜矿为主,脉石矿物中有典型的矽卡岩矿物透辉石、石榴子石。矿床成因类型为矽卡岩型。该矿床的成矿作用主要为热液交代作用,其过程分为矽卡岩期、石英硫化物期和表生期3个成矿时期。