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1.
The Hiendelaencina mining district (Guadalajara, Spain), includes the ore deposits of the Hiendelaencina, La Bodera and Congostrina areas. In this paper a general overview of this district is given, with special emphasis on the parageneses, mineralizing stages and chemical characteristics of the sulphides and sulphosalts. These deposits contain silver in Sb-rich sulphosalts such as freibergite, pyrargyrite, polybasite, stephanite, freieslebenite and the Bi-rich sulphosalt, aramayoite. Three mineralizing stages have been detected in Hiendelaencina and Congostrina: (1) As-Fe; (2) Cu-Zn-Fe-Sb-Ag; and (3) Pb-Sb-Ag (±Bi) but only two in La Bodera (stages 2 and 3). The average sulphosalt formulas are: freibergite (Cu0.5 Ag5.9) (Fe1.42 Zn0.66) (Sb4.49 As0.02) S13; pyrargyrite Ag3.38 Sb1.0 S3; polybasite (Ag16.3Cu0.15) (Sb2.8 As0.15) S11; stephanite Ag6.7 Sb1.38 S4; freieslebenite Ag1.1 Sb0.83 Pb1.05 S3 and aramayoite Ag1.06 Bi0. 35 Sb0.7 Pb0.03 S2. The compositional patterns of these sulphosalts (mainly based on the Sb/(Sb + Ag), Ag/ (Ag + Cu), Sb(Ag + As) and Ag/(Ag + Cu) ratios) are outlined, pointing broadly to similar tendencies in their chemistry and genetic conditions.  相似文献   

2.
The Um Samiuki Zn–Cu–Pb–Ag mineralisation, south Eastern Desert, Egypt is hosted by felsic volcanic rocks which form part of the 712-Ma-old, east-west-trending Shadli Volcanic Belt. Two major occurrences of massive sulphides are present at the top of rhyolitic breccia in the Western and Eastern mine areas. In each occurrence, a bornite-bearing zone is overlain by a pyrite-chalcopyrite-bearing zone and underlain by a disseminated, Cu-depleted zone. In the massive sulphide ore, sphalerite, chalcopyrite, pyrite, galena, bornite and tetrahedrite–tennantite are major minerals, whereas arsenopyrite, pyrrhotite, molybdenite and magnetite are accessory phases. Covellite and digenite are common secondary minerals. Bornite, tetrahedrite–tennantite and covellite contain high amounts of silver (averages of 1.97, 1.39 and 1.82 wt% respectively). Based on mineralogical balance calculations, bornite and covellite accommodate 80% of silver in the Um Samiuki deposit. Ag was incorporated in the crystal structure of the early-crystallised copper sulphides and sulphosalts and silver minerals. The temperature, sequential precipitation of the fluids and the structure of the crystallising phases control the distribution of silver. Post-depositional deformation and metamorphic processes caused liberation, remobilisation and redeposition of silver within the massive sulphides.Editorial handling: D. Lentz  相似文献   

3.
The mineralogy and structure of the supergene profile in recently-exploited volcaniс hosted massive sulphide (VHMS) deposits of Cyprus, Uralian and Kuroko type in the South Urals, Russia, have been studied. Specific subzones enriched in secondary sulphides and associated minerals have been distinguished in residual pyrite and quartz–pyrite sands at the Gayskoye, Zapadno-Ozernoye, Dzhusinskoye and Alexandrinskoye deposits. Besides minerals which are common to the cementation subzones (covellite, chalcocite and acanthite), non-stoichiometric colloform and framboidal pyrite, pyrite–dzharkenite, pyrrhotite-like and jordanite-like minerals, metacinnabar, sphalerite, selenium-enriched tetrahedrite and unidentified As-, Sb sulphosalts of Pb or Hg and Ag, sulphur-bearing clausthalite, naumannite and tiemannite were also found. Secondary sulphide minerals in VHMS deposits of the South Urals region are characterized by light sulphur isotope compositions (− 8.1 to − 17.2‰). Superposition of the advanced oxidation of colloform pyrite, an enrichment in impurities (sphalerite, galena, and tennantite) from the primary ores, stagnant water conditions, an elevation of the water table during oxidation, and bacterial activity led to supergene concentrations of the base metals as sulphide, selenides or sulphosalts.  相似文献   

4.
In this study, changes in surface area, morphology and leachability of antimony from mechanically activated berthierite—FeSb2S4, boulangerite—Pb5Sb4S11 and franckeite—FePb5Sn3Sb2S14 by a high-energy planetary mill were investigated. It appears that a selective extraction of antimony from these complex sulphosalts in alkaline solution of sodium sulphide is positively affected by mechanical activation. The influence of milling on mineral particle size and shape was studied by scanning electron microscopy. The temperature dependencies of berthierite alkaline leaching were investigated in an interval of 323–363 K. Resulting experimental activation energies E a were 0.11 and 6.78 kJ mol−1 for mechanically activated berthierite due to a break of Arrhenius plot. The values E a are characteristic for a process controlled by diffusion as the rate-controlling step of leaching reaction.  相似文献   

5.
Cu-poor meneghinite from La Lauzière Massif (Savoy, France) has the composition (electron microprobe) (in wt%): Pb 59.50, Sb 20.33, Bi 1.19, Cu 0.87, Ag 0.05, Fe 0.03, S 17.62, Se 0.05, Total 99.64. Its crystal structure (X-ray on a single crystal) was solved with R1=0.0506, wR2=0.1026, with an orthorhombic symmetry, space group Pnma, and a=24.080(5) Å, b=4.1276(8) Å, c=11.369(2) Å, V=1130.0(4) Å3, Z=4. Relatively to the model of Euler and Hellner (1960), this structure shows a significantly lower site occupancy factor for the tetrahedral Cu site (0.146 against 0.25). Among the five other metallic sites, Bi appears in the one with predominant Sb. Developed structural formula: Cu0.15Pb2(Pb0.53Sb0.47)(Pb0.46Sb0.54)(Sb0.75Pb0.19Bi0.06)S6; the reduced one: Cu0.58Pb12.72(Sb7.04Bi0.24)S24. The formation of such a Cu-poor variety seems to be related to specific paragenetic conditions (absence of coexisting galena), or to crystallochemical constraints (minor Bi). To cite this article: Y. Moëlo et al., C. R. Geoscience 334 (2002) 529–536.  相似文献   

6.
The lead-zinc-silver bearing vein of Praz-Jean (Vallis, Switzerland) is hosted in a suite of metamorphic rocks, most likely of Palaeozoic age. Sphalerite, galena and sulfosalts (freibergite and boulangérite) are its main ore-forming minerals. The results of the microprobe investigation indicate that the silver is contained in a freibergite of the following composition (weight percent): Cu 23.0, Ag 23.0, Fe 4.9, Zn 1.9, As 1.0, Sb 26.9, S 23.0, and not in an argentian galena as it was believed. The mineral previously described as jamesonite (Pb4FeSb6S14) is in reality a boulangérite (Pb5Sb4S11). The mineralogical and metallogenetic characteristics of the freibergite of Praz-Jean are discussed in relation to those of other ore deposits in which this mineral is of interest.
Resumé Le filon de plomb-zinc-argent de Praz-Jean (Valais, Suisse), se trouve dans un encaissant composé de roches métamorphiques vraisemblablement d'âge Paléozoïque. Ses minéraux constitutifs, qui ont été étudiés en détail à la microsonde, appartiennent à une suite classique de sulfures à blende et galène dominantes, et de sulfosels (freibergite, boulangérite). L'argent du gisement n'est pas contenu dans une galène argentifère comme on le croyait auparavant, mais dans une freibergite de composition pondérale: Cu 23,0, Ag 23,0, Fe 4,9, Zn 1,9, As 1,0, Sb 26,9, S 23,0. Le minéral décrit précédemment comme jamesonite (Pb4FeSb6S14) est en réalité une boulangérite (Pb5Sb4S11). La freibergite de Praz-Jean est comparée du point de vue minéralogique et gîtologique à des freibergites d'autres gisements dans lesquels la freibergite joue un rôle important.
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7.
Silica-tube quenching experiments and gold-tube pressure experiments were used to study phase relations in the PbS-rich portion of the system Pb-As-S. Emphasis was placed on determining the P-T-X stability relations of jordanite, the most Pb-rich of the synthetic Pb-As-S compounds. Jordanite, Pb9As4S15, is stable below 549 ± 3° C, at which temperature it melts to galena, liquid, and a sulfur-rich vapor phase. Confining pressures of up to 2 Kb do not measurably change this reaction temperature. Density measurements on synthetic material show that the jordanite cell contains 3 (Pb9As4S15); space group P21/m requires that the cell content be expressed as either Pb28–xAs12S46–x or Pb26+xAs12S44+x, with the former much more probable from a structural point of view. In both cases 0.8 < x < 1.4 and the situation is thus quite different from the usual case of defect structures, such as pyrrhotite, Fe1–xS, which shows considerable range of solid solution. Heating experiments on natural gratonite (Pb9As4S15) show that this mineral is most probably a low-temperature dimorph of jordanite, the inversion occurring below 250° C. Experiments have also confirmed the extensive substitution of Sb for As in jordanite, as suspected from chemical analyses of the isostructural mineral geocronite (Pb28–x(As,Sb)12S46–x).
Zusammenfassung Durch Abschreckversuche mit Hilfe von Quarz- und Gold-Druckampullen wurden die Phasenbeziehungen im PbS-reichen Teil des Pb-As-S-Systems studiert. Besonderer Wert wurde auf die Feststellung der P-T-X-Stabilitätsverhältnisse des Jordanits, des Pb-reichsten Phase der synthetischen Pb-As-S-Reihe, gelegt. Jordanit (Pb9As4S15) ist unterhalb 549 ± 3° C stabil, wo er sich semikongruent zu PbS, einer Schmelze und einer schwefelreichen Dampfphase zersetzt. Drucke bis zu 2 kb ergaben keine meßbaren Änderungen dieser Reaktionstemperatur. Dichtemessungen am synthetischen Material weisen darauf hin, daß die Jordanitzelle 3 × (Pb9As4S15) enthält. Die Raumgruppe P21/m fordert entweder die Formel Pb28–xAs12S46–x oder Pb26+xAs12S44+x, wobei die erstere Form strukturell wahrscheinlicher zu sein scheint. In beiden Fällen ist 0.8 < x < 1.4 und weicht vom gebräuchlichen Begriff der Defektstrukturen, wie z.B. beim Pyrrhotin (Fe1–xS) ab, wie das bemerkenswerte Mischkristallfeld zeigt. Erhitzen von natürlichem Gratonit (Pb9As4S15) zeigt, daß dieses Mineral sehr wahrscheinlich eine dimorphe Tieftemperaturphase des Jordanits ist. Die Umwandlung erfolgt unterhalb 250° C. Außerdem wurde eine umfangreichere Substitution von As durch Sb im Jordanit festgestellt, was nach den chemischen Analysen des isostrukturellen Geochronits Pb28–x(As,Sb)12S46–x) zu erwarten war.
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8.
Summary The Golden Sunlight gold-silver telluride deposit, hosted primarily within the Mineral Hill breccia pipe (MHBP), is spatially related to a high-level, Late Cretaceous multiple intrusive, alkaline to subalkaline porphyry system. Base metal veins and manganese (rhodochrosite) mineralization occur up to 2km from the MHBP and form part of a regional mineral zonation pattern genetically related to a low-grade porphyry molybdenum system. Proterozoic rocks of the LaHood Formation and the informally named Bull Mountain Group host the MHBP and contain stratabound sulphides/ sulphosalts (up to 50% pyrite with minor to trace amounts of chalcopyrite, tennantite, pyrrhotite, sphalerite, galena, and molybdenite). Four periods of hypogene mineralization occur in the breccia pipe. Stages I and IV constitute ,99% of the mineralization; native gold (4–11 wt.% Ag), calaverite, tetradymite, tellurobismuthite, Se-bearing Bi sulphosalts (aikinite, lindströmite, krupkaite, gladite, bismuthinite, and ?benjaminite), tennantite (Zn, Fe, Te, and Bi varieties), coloradoite, melonite, galena (up to 6.7 wt.% Bi and 6.4 wt.% Se), stannite, chalcocite, and the rare mineral buckhornite are included in stage Ib. Minor amounts of base metals are present in stage II. Gold-silver tellurides (krennerite, petzite, sylvanite, and possibly the rare x-phase) developed in stage III whereas barite, fluorite, dolomite, magnesite, trace kaolinite, and sericite formed during stage IV. Utilizing the mineral assemblages in stage Ib, calculated values of logf Te2 and logf S2 range from -10.5 to -9.7, and -12.6 to -5.5, respectively.Ore forming components (e.g., Au, Ag, Te, Cu, Bi, Mo, and much of the S) were likely derived from the Late Cretaceous intrusive system with possible contributions from the Proterozoic host rocks.
Mineralogie der Golden Sunlight Gold-Silber-Tellurid-Lagerstätte, Whitehall, Montana
Zusammenfassung Die Golden Sunlight Gold-Silber-Tellurid-Lagerstätte, die hauptsächlich im Brekzienschlot von Mineral Hill (Mineral Hill breccia pipe, MHBP) eingelagert ist, steht räumlich mit einem erzreichen, multi-intrusiven, alkalischen bis sub-alkalischen Porphyritsystem aus der Oberkreide in Beziehung. Erzadern und Mn-Mineralisation (Rhodochrosit) finden sich bis zu 2 km vom MHBP entfernt und sind Bestandteil einer regionalen Vererzung die genetisch zu einem erzarmen Mo-hältigen Porphyritsystem in Beziehung steht. Proterozoische Gesteine aus der LaHood-Formation und der inoffiziell benannten Bull Mountain Group umgeben den MHBP und enthalten schichtgebundene Sulfide und Sulfosalze (bis zu 50% Pyrit mit Neben- bis Spurenmengen von Kupferkies, Tennantit, Pyrrhotin, Zinkblende, Bleiglanz und Molybdänit).[Der Brekzienschlot zeigt vier Phasen hypogener Mineralisation. Stufen I und IV enthalten 99% der Mineralisation: gediegen Gold (4–11 Gew.% Ag), Calaverit, Tetradymit, Tellurobismuthit, Se-hältige Bi-Sulfosalze (Aikinit, Lindströmit, Krupkait, Gladit, Bismuthinit und ?Benjaminit) Tennantit (Zn-, Fe-, Te- und Bi-Varietäten), Coloradoit, Melonit, Bleiglanz (mit bis zu 6.7 Gew.% Bi und 6.4 Gew.% Se), Zinnstein, Chalcocit, sowie das seltene Mineral Buckhornit treten in Stufe Ib auf. Geringere Mengen von Buntmetallen kommen in Stufe II vor. Gold-Silber-Telluride (Krennerit, Petzit, Sylvanit und möglicherweise die seltene X-Phase) sind in Stufe III ausgebildet und in Stufe IV wurden Baryt, Flusspat, Dolomit, Magnesit, Spuren von Kaolin und Serizit gebildet. Unter Verwendung der Mineralassoziationen der Stufe Ib lassen sich Werte von logf Te2 zwischen - 10.5 und - 9.7 und von logf S2 zwischen - 12.6 und - 5.5 errechnen.[Die erzbildenden Komponenten (z.B. Au, Ag, Te, Cu, Bi, Mo und der Grossteil von S) stammen wahrscheinlich vom Intrusivsystem aus der Oberkreide, möglicherweise mit Beiträgen der proterozoischen Umgebung.[/ p]

With 10 Figures  相似文献   

9.
Syntectonic hydrothermal Pb-Zn vein systems of the Ramsbeck deposit, Germany, have been extensively overprinted by late-stage fluids responsible for fissure vein mineralisation. This has caused remobilisation of vein components, notably of sphalerite and galena, as well as the formation of various Sb sulphosalt minerals, including boulangerite, semseyite, tetrahedrite and bournonite. A detailed sulphur isotope study of sphalerite, galena and sulphosalts related to different stages of recrystallisation, remobilisation and reaction has been carried out using an insitu laser combustion technique. Primary sphalerite-galena ores from flat-lying thrust zones are characterised by homogeneous positive '34S values in the range +6.5 to +7.7‰. In contrast, recrystallised and remobilised sphalerite and galena from both overprinted thrust zones and extensional fissure veins show '34S values in the range -1.1 to +2.9‰ and -0.7 to +8.7‰ respectively. Sulphosalt minerals show a similar variation in their sulphur isotope compositions, which range between -1.7 and +7.7‰. Fissure vein hosted sphalerite and sulphosalts display significantly more negative '34S values than the primary Pb-Zn ores. Sphalerite which recrystallised in situ and boulangerite which formed by reactive replacement of primary galena show slightly more positive '34S values than fissure vein hosted minerals. The compositional range of remobilised mineral phases can be best explained by varying contributions (variable mixing) of sulphur derived from (1) the primary sphalerite-galena ores of the flat thrust systems, and (2) the hydrothermal fluid responsible for the fissure vein mineralisation. Equilibrium fractionation temperatures calculated for sphalerite-galena pairs contrast strongly with fluid inclusion data. Isotopic fractionation related to the remobilisation has to be interpreted in terms of kinetic processes.  相似文献   

10.
Summary The Abakaliki lead-zinc deposit in the lower Benue Trough (Nigeria) represents the largest of a series of fracture controlled base metal deposits within the Lower Cretaceous (Albian) Asu River Group shales. Field evidence, ore microscopy and electron microprobe analysis of the lodes, suggest that the vein mineralization commenced with pre-ore precipitation of diagenetic marcasite, pyrite and minor gel-like colloform textured schalenblende and galena especially at the vein/wall rock contacts. This was succeeded by an ore stage consisting mainly of sphalerite, galena, chalcopyrite and pyrite. Accessories include bournonite and boulangerite. There was also a later introduction of complex intergrowths comprising bornite, chalcocite, enargite, and tennantite. In addition a lead/iron bearing copper sulphide and a copper bismuth sulphide of wittichenite composition (Cu6Bi2SO6), the optical parameters of which do not agree with those of wittichenite, were also introduced. The late stage copper sulphides and sulphosalts were formed as replacements of earlier lower temperature (ca. 170°C) main phase mineralization, when temperature rose in minimum up to 230°C.
Koexistierende Kupfer-Sulfide und Sulfosalze in der Blei-Zink-Iagerstätte Abakaliki, Unterer Benue-Graben (Nigeria) und ihre genetische Bedeutung
Zusammenfassung Die Blei-Zink-Lagerstätte Abakaliki im Unteren Benue-Graben (Nigeria) ist die größte einer Reihe von durch Bruchstrukturen bestimmten Buntmetallagerstätten innerhalb der unterkretazischen (Albian) Asu River Group Shales. Geländebeobachtungen, Erzmi-kroskopie undzeigen, Mikrosondenanalysen zeigen, daß die Gangmineralisation mit der Ablagerung von diagenetischem Markasit, Pyrit und, in kleinerem Ausmaß gel-ähnlicher kolloformer Schalenblende und Bleiglanz, besonders an den Kontaktzonen zwischen Gängen und Nebengestein begonnen hat. Darauf folgte ein Stadium der Erzablagerung, wobei es hauptsächlich zur Bildung von Zinkblende, Bleiglanz, Kupferkies und Pyrit kam. Bournonit und Boulangerit kommen als Nebengemengteile vor. Schließlich gab es eine spätere Bildung von komplexen Verwachsungen, die aus Bornit, Kupferglanz, Enargit und Tennantit bestehen. Außerdem kam es zum Absatz eines Blei-Eisenführenden Kupfersulfids und eines Kupfer-Wismut-Sulfids, dessen Zusammensetzung mit der von Wittichenit (Cu6B22S6) übereinstimmt, dessen optische Parameter jedoch anders sind. Die späten Kupfersulfide und Sulfosalze wurden durch Verdrängung von früheren Tieftemperaturerzen (ca. 170°C) der Hauptphase gebildet, wo die Temperaturen mindestens bis auf 230°C anstiegen.

With 4 Figures  相似文献   

11.
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12.
Mesothermal vein-type Sb mineralization in the Rheinisches Schiefergebirge, Germany, is characterized by two different mineralization styles, which are (1) extensional quartz-stibnite vein systems, and (2) (Cu)-Pb-Sb sulphosalt assemblages in overprinted pre-existing Pb-Zn veins. A detailed Pb isotope study of 52 representative samples from both mineralization types indicates distinct compositional patterns. (Cu)-Pb-Sb sulphosalts (meneghinite, boulangerite, bournonite) formed by reaction/remobilization are characterized by Pb isotope compositions (206Pb/204Pb=18.179-18.223), which are identical to the precursor galena (206Pb/204Pb=18.168-18.223). The Pb isotope composition of sulphosalt minerals in these vein systems was controlled by lead inherited from pre-existing galena. Stibnite and Pb-sulphosalts (zinkenite, semseyite, plagionite) formed in quartz-stibnite vein systems display Pb isotope ratios (206Pb/204Pb=18.250-18.354), which are more radiogenic than galenas from Variscan Pb-Zn ore veins (206Pb/204Pb=18.162-18.303). Detailed small-scale investigation of thrust zones hosting Pb-Zn ores and crosscutting quartz-ankerite fissure veins (Ramsbeck deposit) indicates that the Pb isotope compositions of recrystallized (galena) and remobilized phases (boulangerite, semseyite, bournonite) are arranged along a linear trend. This is interpreted as mixing between primary galena with 206Pb/204Pb᜞.206 and overprinting hydrothermal fluids with a more radiogenic composition (206Pb/204Pb⁾.354), expressed by intermediate compositions (206Pb/204Pb=18.256-18.334) of newly-formed sulphosalts. The Pb isotope systematics of the vein-type Sb mineralization is in accordance with a model of Pb extraction from similar crustal sources (Palaeozoic sedimentary sequences) at different times.  相似文献   

13.
A new argyrodite occurrence has been discovered in the Ro?ia Montan? ore deposit located in the South Apuseni Mountains, Romania. Argyrodite is associated with common base metal sulfides and sulfosalts (galena, sphalerite, chalcopyrite, tetrahedrite ± alabandite, pyrite, and marcasite), tellurides (hessite, altaite, sylvanite) and rare electrum grains in the Ag-rich Cârnicel vein hosted by an extracraterial phreatomagmatic breccia within the Cârnic massif. SEM and EPMA analyses revealed that this argyrodite is Te-rich and a mean Ag8.04Ge0.9Te2.07S3.77 formula was calculated. This phase could be the germaniferous equivalent of the previously-described Te-rich canfieldite. To cite this article: L. Bailly et al., C. R. Geoscience 337 (2005).  相似文献   

14.
The stringer zones and commonly the interaction zone at the base of the massive sulphide mounds in the Iberian Pyrite Belt contain bismuth and cobalt minerals that are not found in the overlying massive sulphides. These are fairly rare cobalt sulphoarsenides (cobaltite, alloclasite, galucodot) that were formed at the beginning of the massive sulphide genesis, and fairly common bismuth sulphides (bismuthinite, hammarite, wittichenite, cosalite, kobellite, joseite, etc.), including species rare at world scale (nuffieldite, giessenite, jaskolskiite) that were deposited from last stage high-temperature (> 300 °C) copper-bearing fluids containing Bi (Te, Se). The last stage fluids precipitated chalcopyrite containing Cu, Bi, Te, (Se) sulphosalts at the base of the sulphide mound to form a high cupriferous zone. Their interaction with the massive sulphides is reflected by the formation of an exchange zone, a few metres thick, showing chalcopyrite disease textures, at the base of the mound; this zone forms the upper limit of potentially economic copper enrichment and of bismuth minerals. Gold is undoubtedly in part, if not totally, related to this last phase. The bismuth concentrations being equivalent in the massive sulphides and the stringers, the presence of bismuth minerals in the stringer zones results from high-temperature conditions combined with a rarity of galena, which impedes absorption of available Bi. The distribution of these bismuth minerals provides a basic mineralogical zoning in the stringer zone, with a deep, low-aS2 zone containing native bismuth and tellurides and a shallow, higher-aS2 zone in contact with the massive ore sensu stricto and containing complex bismuth sulphides. These results make it possible to distinguish between sulphide veinlets belonging to stockwork zones of massive orebodies and veinlets of an ambiguous nature, and provide mineralogical criteria for the proximity of copper-rich zones. They enrich the very complex mineralogy of the Iberian Pyrite Belt.  相似文献   

15.
Summary The Early Paleozoic Altkristallin of the Kreuzeck Mountains is well-known for its mostly small gold, silver, copper, lead, zinc, antimony, and mercury deposits. A detailed investigation of silver(-gold)-base metal mineralizations (Plattach, Niedermülleralm, Grakofel and DraBnitz) is presented in this paper. The deposits are structurally controlled. Faults and shear zones penetrate garnet-mica schists, gneisses (partly at Grakofel), and amphibolites (partly at DraBnitz). In places the mineralization occurs at the sheared contact between quartz porphyrite dykes (K/Ar ages of 30–40 Ma) and country rocks (e.g. at Niedermülleralm).The precious metal mineralization occurs as bundles of quartz veins, which were mined over a distance of 150-200 m along strike and dip. The depositional textures such as vugs, symmetrical banding, cockade and colloform structures clearly indicate open space filling. The mineral parageneses of Plattach, Niedermülleralm and Grakofel ores are similar to each other, but distinctly different from that of the DraBnitz deposit. The first mentioned deposits are characterized by abundant silver sulfosalts such as freibergite (21.7–36.3 wt.% Ag), pyrargyrite, miargyrite, diaphorite (Pb1 7–1.8Ag2.9–3.2Sb2.8–3.0S8), owyheeite (Ag2.69Pb9.44Sb10.38S28) and stephanite, as well as sphalerite and galena (100–1600 ppm Ag); hocartite ( [Ag, Cu]2 [Fe, Zn] SnS4) is intergrown with pyrargyrite and occurs as inclusions in pyritic ores at Niedermülleralm. Pyrite, arsenopyrite, and chalcopyrite are present in minor amounts. Au-Ag alloys with Ag contents ranging between 40.4–49.5 wt.% (electrum) and 73.5–74.2 wt.% (aurian silver) have grain sizes between 2 and 60 pin and are frequently associated with freibergite, pyrite and quartz.Draßnitz is a silver bearing base metal deposit with a possible but not proved silver enrichment in the uppermost 100 m of the vein system. Arsenopyrite, pyrrhotite, chalcopyrite, sphalerite, bournonite, Ag-tetrahedrite, and galena are the dominant ore minerals, locally accompanied by substantial amounts of zincian stannite (25 mol.% kesterite), ferberite, scheelite, and minor amounts of molybdenite, native bismuth, ullmannite and a silver sulfosalt.The most common types of hydrothermal wall-rock alteration are phyllic alteration (sericitization), silicification, carbonatization, and sulfidization. The alteration zone does not exceed a few decimeters on both sides of the veins.Fluid inclusion studies of quartz reveal formation temperatures of 165–250°C (Plattach) and 165–220°C (Niedermülleralm). The corresponding data for the Grakofel and Draßnitz ores are 180–330°C and 210–365°C, respectively. The salinities vary between 3–7 equiv. wt.-% NaCl (Niedermülleralm, Plattach, Draßnitz) and 4–13.3 equiv. wt.-% NaCl (Grakofel).A shallow-seated plutonic or subvolcanic magma (quartz porphyrite?) could be the reason for telescoping, different temperatures and heat gradient within the mineralized zone. The isotope compositions of the fluids give evidence for their metamorphic origin, probably contaminated by a minor meteoric component.
Gangförmige Ag-(Au)-Pb, Zn, Cu-(W, Sn) Vererzungen in der südlichen Kreuzeckgruppe, Kärnten, Österreich
Zusammenfassung Das altpaläozoische Altkristallin der Kreuzeckgruppe beherbergt eine große Zahl zumeist kleiner Gold-, Silber-, Kupfer-, Blei-, Zink-, Antimon- und Quecksilber-Lagerstätten. In dieser Arbeit werden detaillierte Untersuchungen von Silber(-Gold)-Buntmetall-Vererzungen (Plattach, Niedermülleralm, Grakofel und Draßnitz) vorgestellt. Die Lagerstätten sind strukturkontrolliert; Verwerfungs- und Scherzonen setzen in Granat-glimmerschiefern, Gneisen (teilweise Grakofel) und Amphiboliten (teilweise Draßnitz) auf. Bereichsweise tritt die Vererzung am zerscherten Kontakt zwischen Quarzporphyritgängen (K/Ar-Alter 30–40 Ma) und dem Nebengestein auf (z.B. Niedermülleralm).Die edelmetallhältige Vererzung ist an Quarzgang-Systeme gebunden, deren Ausdehnung aufgrund der bergbaulichen Aktivitäten kaum mehr als 150–200 m im Streichen und Einfallen betragen haben dürfte. Die beobachteten Ablagerungstexturen mit zahlreichen Drusen, symmetrischen Bänderungen, Kokarden- und kolloformen Strukturen sind eindeutige Indizien für eine Kristallisation in Hohlräumen. Die Mineral-paragenesen der Reviere Plattach-Niedermülleralm und des Grakofels sind einander sehr ähnlich, unterscheiden sich aber deutlich von jenen der Draßnitz. Die erstgenannten Lagerstätten zeichnen sich durch das bevorzugte Auftreten von Silber-Sulfosalzen, wie Freibergit (21,7–36,3 Gew.% Ag), Pyrargyrit, Miargyrit, Diaphorit (Pb1,7–1,8Ag2,9–3,2 Sb2,8–3,0S8), Owyheeit (Ag2. 69Pb9 ,44Sb10,38S28) und Stephanit sowie Sphalerit und Galenit (100–1600 ppm Ag) aus; Hocartit ( [Ag, Cu]2 [Fe, Zn] SnS4), der mit Pyrargyrit verwachsen ist, bildet Einschlüsse in Pyriterzen der Niedermülleralm. Zu geringeren Teilen kommen Pyrit, Arsenopyrit und Chalkopyrit vor. Gold-Silber-Legierungen mit Ag-Gehalten zwischen 40,4–49,5 Gew.% (Elektrum) und 73,5–74,2 Gew.% (Au-hältiges Silber) und Korngrößen zwischen 2 und 60 Mm sind häufig mit Freibergit, Pyrit und Quarz assoziiert.Die Lagerstätten der Draßnitz enthalten eine silberführende Buntmetallvererzung mit einer aufgrund der alten Bergbautätigkeit nur vermutbaren ehemaligen Silber-Reicherzzone in den obersten Gangabschnitten (Mächtigkeit ca. 100 m). Die Haldenerze bestehen heute aus Arsenopyrit, Pyrrhotin, Chalkopyrit, Sphalerit, Bournonit, Ag-Tetraedrit und Galenit; sie werden bereichsweise von beträchtlichen Anteilen an Zn-Stannit (25 Mol.% Kesterit), Ferberit, Scheelit, sowie in geringen Mengen von gediegenem Wismut, Ullmannit und Ag-Sulfosalzen begleitet.Serizitisierung, Silizihzierung, Karbonatisierung und Sulfidisierung sind die wesentlichen hydrothermalen Nebengesteinsveränderungen. Die Alterationszone erreicht allerdings nur einige Dezimeter auf beiden Seiten der Erzgänge.Die aus Flüssigkeitseinschlüssen in Quarz ermittelten Bildungstemperaturen zeigen für die Plattach 165–250°C, für die Niedermülleralm 165–220T. Die entsprechenden Temperaturdaten für die Grakofel-Vererzung betragen 180–330°C und 210–365°C für die Draßnitz. Die Salinitäten schwanken zwischen 3–7 Gew.% NaCl äq. (Niedermülleralm, Plattach, Draßnitz) und 4–13,3 Gew.% NaCl äq. (Grakofel).Ein hochplutonisches oder subvulkanisches Magma (Quarzporphyrit?) könnte eine mögliche Erklärung für das Teleskoping, die Temperaturunterschiede und den Wärmegradienten innerhalb der Vererzungszone sein. Die Isotopenzusammensetzung der Fluide deutet auf deren metamorphen Ursprung mit vermutlich untergeordneter meteorischer Komponente hin.

(Herrn Univ. Prof. Dr. Ing. 0. M. Friedrich () in Erinnerung zugeeignet)

With 10 Figures  相似文献   

16.
The Birgilda–Tomino ore cluster in the East Uralian zone, South Urals, Russia, hosts a variety of Late Paleozoic porphyry copper deposits (Birgilda, Tomino, Kalinovskoe, etc.), high- and low sulfidation epithermal deposits (Bereznyakovskoe, Michurino), and skarn-related base metal mineralization (Biksizak) in carbonate rocks. The deposits are related to quartz diorite and andesite porphyry intrusions of the K–Na calc-alkaline series, associated to a subduction-related volcanic arc. We report microprobe analyses of ore minerals (tetrahedrite–tennantite, sphalerite, Bi tellurides and sulfosalts, Au and Ag tellurides), as well as fluid inclusion data and mineral geothermometry. On the basis of these data we propose that the Birgilda–Tomino ore cluster represents a porphyry–epithermal continuum, with a vertical extent of about 2–3 km, controlled by temperature decreases and fS2 and fTe2 increase from deeper to shallow levels.  相似文献   

17.
Abstract. Germanium‐bearing colusite occurs with sphalerite, galena, tetrahedrite‐tennantite, chalcopyrite and pyrite in microdruses and veinlets in the siliceous black ore from the Ezuri Kuroko deposit in the Hokuroku district of Japan. X‐ray microdiffractometry of this mineral gives strongest lines at 1.60, 1.32 and 1.09 Å, which are consistent with the known powder diffraction data of colusite. On the basis of 32 S atoms per formula unit, electron microprobe analyses yield empirical chemical formulae of (Cu24 0Fe0.3Zn1.0)σ25.3V1.9(As4.8Sb0.2)σ5.0Ge 1.3S32 for Ge‐bearing colusite in close association with sphalerite, and (Cu24.6Fe0.9)σ25.4V1.8(As4.1 Sb0.2)σ4.3Ge1.7S32 for that coexisting with chalcopyrite, consistent with the ideal formula of Cu24+xV2(As, Sb)6‐x(Sn, Ge)xS32 (x = 0 to 2) proposed by Spry et al. (1994) for this mineral species. The Ge‐bearing colusite mineralization is suggested to have occurred concurrently with consolidation of the siliceous black ore, possibly during hydrothermal modification in association with the igneous activity of the Ohtaki quartz diorite of the later Onnagawa stage. It is likely that biogenic siliceous ooze, a possible precursor of the siliceous black ore, may have served as an in situ source of Ge as well as other essential rare elements, leading to the formation of Ge‐bearing colusite during transformation or recrystallization of biogenic opal into a‐quartz.  相似文献   

18.
The Vangorda orebody is a small stratiform massive sulphide orebody located in Anvil District, Yukon, Canada. The orebody consists of fineto medium-grained semi-massive and massive sulphides with a common sulphide mineralogy of pyrite, pyrrhotite, sphalerite, galena, and minor chalcopyrite. The host rocks and the sulphide lithofacies have been complexly deformed during two phases of deformation (D1 and D2) and associated metamorphism (M1 and M2). The effects of d1 and M1 are penetratively overprinted by D2 and M2. D2 and M2 resulted in tight to isoclinal F2 folding of the orebody, remobilisation of the sulphides, recrystallisation and development of shear zones along the limbs of the F2 folds. Chlorite thermometry and sulphide thermobarometry have been carried out on the host phyllites and on the sulphides. Chlorite was analysed from the S1 and S2 foliations in the phyllites to determine M1 and M2 temperatures, respectively. However, no difference was found between chlorite compositions in these foliations and a mean temperature of 363 °C was calculated from the tetrahedral A1IV occupancy. Arsenopyrite thermometry yielded a comparable mean temperature of 336 °C. Sphalerite inclusions in M2 pyrite porphyroblasts from D2 shear zones were analysed for pressure using the sphalerite + hexagonal pyrrhotite + pyrite barometer. Inclusions were analysed in an attempt to determine if relic m1 sphalerite, and hence pressure signature, was preserved. Inclusion compositions appear to reflect only M2 conditions and yielded a mean pressure of 4.0 kb. Sphalerite + hexagonal pyrrhotite assemblages were analysed from D2 shear zones to determine the M2 pressure using the sphalerite + hexagonal pyrrhotite barometer. These calculations yielded a mean pressure of 6.1 kb. The M2 temperatures and pressures calculated using these calibrations are in good agreement with those estimated from petrogenetic relationships.  相似文献   

19.
Evacuated silica tube experiments (+halide flux) were conducted in portions of the system Cu2S-PbS-Sb2S3 at 440°C, using two-pyrrhotite indicator method to measure the sulfur fugacity. Product phases were identified by optical and X-ray powder diffraction methods supplemented with microprobe analyses. In addition to the previously reported mineral phases, famatinite (Cu3SbS4) appears to be a stable phase in the Sb2S3-rich portion of the system. Microprobe data indicate that almost all the sulfosalts depart from stoichiometry. Copper in Pb-Sb sulfosalts and Pb in chalcostibite and skinnerite are indicative of the coupled substitution 2Pb2+=Cu++Sb3+. Pb-solubility in skinnerite and Cu-solubility in zinkenite are dependent on the initial bulk composition of the charges. The compositions of meneghinite and boulangerite compare well with their natural analogues. The maximum isothermal variation of logf s 2 falls in the range of-6.36 (1.06)logf s 211.12 (0.30). The experimentally derived logf s 2 values for some two phase assemblages, compare reasonably well with the respective minimum logf s 2 values calculated by the method of Craig and Barton (1973). The stable coexistence of famatinite with zinkenite plus stibnite instead of chalcostibite may be described by the sulfidation reaction: 3CuSbS2+1/2 S2=Cu3SbS4+Sb2S3.  相似文献   

20.
A cervelleite-like mineral, two unnamed silver sulfotellurides in the system Ag-Cu-Te-S [Ag2CuTeS, (Ag,Cu)2TeS], Te-rich polybasite and cadmian tetrahedrite occur in gold-bearing quartz veins in metapelites and faults within brecciated marbles of the Cycladic Blueschist Unit in the Kallianou area (southern Evia Island, Greece). The quartz veins and faults are discordant to syn-metamorphic structures and formed during ductile to brittle deformation in the final stages of exhumation of the Styra Nappe extrusion wedge (~21?Ma). Te-rich polybasite (up to 7.4 wt. % Te), cadmian tetrahedrite (up to 12.4 wt. % Cd), together with electrum (23?C54 wt. % Ag) and the sulfotellurides, are the main silver carriers in the mineralization. The two unnamed sulfotellurides, Ag2CuTeS and (Ag,Cu)2TeS are believed to be new quaternary minerals in the system Ag-Cu-Te-S. These minerals and the cervelleite-like phase could have exsolved from galena during cooling (below 200°C). Initial temperatures for the formation of the sulfotellurides, in the form of hessite-intermediate solid solution, at Kallianou may be up to 300°C under logfS2 values between?~ ?11.5 to ?8.3, and logfTe2 from?~ ?14.8 to ?7.8. The values of logfTe2 and logfS2 during re-equilibration (at ~200°C) were constrained to ?19.5 to ?15.2 and to ?15.8 to ?11.5 respectively.  相似文献   

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