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1.
Gossan Hill is an Archean (∼3.0 Ga) Cu–Zn–magnetite-rich volcanic-hosted massive sulfide (VHMS) deposit in the Yilgarn Craton
of Western Australia. Massive sulfide and magnetite occur within a layered succession of tuffaceous, felsic volcaniclastic
rocks of the Golden Grove Formation. The Gossan Hill deposit consists of two stratigraphically separate ore zones that are
stratabound and interconnected by sulfide veins. Thickly developed massive sulfide and stockwork zones in the north of the
deposit are interpreted to represent a feeder zone. The deposit is broadly zoned from a Cu–Fe-rich lower ore zone, upwards
through Cu–Zn to Zn–Ag–Au–Pb enrichment in the upper ore zone. New sulfur isotope studies at the Gossan Hill deposit indicate
that the variation is wider than previously reported, with sulfide δ34S values varying between −1.6 and 7.8‰ with an average of 2.1 ± 1.4‰ (1σ error). Sulfur isotope values have a broad systematic
stratigraphic increase of approximately 1.2‰ from the base to the top of the deposit. This variation in sulfur isotope values
is significant in view of typical narrow ranges for Archean VHMS deposits. Copper-rich sulfides in the lower ore zone have
a narrower range (δ34S values of −1.6 to 3.4‰, average ∼1.6 ± 0.9‰) than sulfides in the upper ore zone. The lower ore zone is interpreted to have
formed from a relatively uniform reduced sulfur source dominated by leached igneous rock sulfur and minor magmatic sulfur.
Towards the upper Zn-rich ore zone, an overall increase in δ34S values is accompanied by a wider range of δ34S values, with the greatest variation occurring in massive pyrite at the southern margin of the upper ore zone (−1.0 to 7.8‰).
The higher average δ34S values (2.8 ± 2.1‰) and their wider range are explained by mixing of hydrothermal fluids containing leached igneous rock
sulfur with Archean seawater (δ34S values of 2 to 3‰) near the paleoseafloor. The widest range of δ34S values at the southern margin of the deposit occurs away from the feeder zone and is attributed to greater seawater mixing
away from the central upflow zone.
Received: 10 June 1999 / Accepted: 28 December 1999 相似文献
2.
Vein-type tin mineralization in the Dadoushan deposit, Laochang ore field, Gejiu district, SW China, is predominantly hosted in Triassic carbonate rocks (Gejiu Formation) over cupolas of the unexposed Laochang equigranular granite intrusion. The most common vein mineral is tourmaline, accompanied by skarn minerals (garnet, diopside, epidote, phlogopite) and beryl. The main ore mineral is cassiterite, accompanied by minor chalcopyrite, pyrrhotite, and pyrite, as well as scheelite. The tin ore grade varies with depth, with the highest grades (~1.2 % Sn) prevalent in the lower part of the vein zone. Muscovite 40Ar–39Ar dating yielded a plateau age of 82.7 ± 0.7 Ma which defines the age of the vein-type mineralization. Measured sulfur isotope compositions (δ 34S = −4.1 to 3.9 ‰) of the sulfides (arsenopyrite, chalcopyrite, pyrite, and pyrrhotite) indicate that the sulfur in veins is mainly derived from a magmatic source. The sulfur isotope values of the ores are consistent with those from the underlying granite (Laochang equigranular granite, −3.7 to 0.1 ‰) but are different from the carbonate wall rocks of the Gejiu Formation (7.1 to 11.1 ‰). The calculated and measured oxygen and hydrogen isotope compositions of the ore-forming fluids (δ 18OH2O = −2.4 to 5.5 ‰, δD = −86 to −77 ‰) suggest an initially magmatic fluid which gradually evolved towards meteoric water during tin mineralization. 相似文献
3.
The Mississippi Valley-type (MVT) Pb–Zn ore district at Mežica is hosted by Middle to Upper Triassic platform carbonate rocks
in the Northern Karavanke/Drau Range geotectonic units of the Eastern Alps, northeastern Slovenia. The mineralization at Mežica
covers an area of 64 km2 with more than 350 orebodies and numerous galena and sphalerite occurrences, which formed epigenetically, both conformable
and discordant to bedding. While knowledge on the style of mineralization has grown considerably, the origin of discordant
mineralization is still debated. Sulfur stable isotope analyses of 149 sulfide samples from the different types of orebodies
provide new insights on the genesis of these mineralizations and their relationship. Over the whole mining district, sphalerite
and galena have δ
34
S values in the range of –24.7 to –1.5‰ VCDT (–13.5 ± 5.0‰) and –24.7 to –1.4‰ (–10.7 ± 5.9‰), respectively. These values are
in the range of the main MVT deposits of the Drau Range. All sulfide δ
34
S values are negative within a broad range, with δ
34
S
pyrite <δ
34
S
sphalerite <δ
34
S
galena for both conformable and discordant orebodies, indicating isotopically heterogeneous H2S in the ore-forming fluids and precipitation of the sulfides at thermodynamic disequilibrium. This clearly supports that
the main sulfide sulfur originates from bacterially mediated reduction (BSR) of Middle to Upper Triassic seawater sulfate
or evaporite sulfate. Thermochemical sulfate reduction (TSR) by organic compounds contributed a minor amount of 34S-enriched H2S to the ore fluid. The variations of δ
34
S values of galena and coarse-grained sphalerite at orefield scale are generally larger than the differences observed in single
hand specimens. The progressively more negative δ
34
S values with time along the different sphalerite generations are consistent with mixing of different H2S sources, with a decreasing contribution of H2S from regional TSR, and an increase from a local H2S reservoir produced by BSR (i.e., sedimentary biogenic pyrite, organo-sulfur compounds). Galena in discordant ore (–11.9
to –1.7‰; –7.0 ± 2.7‰, n = 12) tends to be depleted in 34
S compared with conformable ore (–24.7 to –2.8‰, –11.7 ± 6.2‰, n = 39). A similar trend is observed from fine-crystalline sphalerite I to coarse open-space filling sphalerite II. Some variation
of the sulfide δ
34
S values is attributed to the inherent variability of bacterial sulfate reduction, including metabolic recycling in a locally
partially closed system and contribution of H2S from hydrolysis of biogenic pyrite and thermal cracking of organo-sulfur compounds. The results suggest that the conformable
orebodies originated by mixing of hydrothermal saline metal-rich fluid with H2S-rich pore waters during late burial diagenesis, while the discordant orebodies formed by mobilization of the earlier conformable
mineralization. 相似文献
4.
The strata-bound Cu−Pb−Zn polymetallic sulfide deposits occur in metamorphic rocks of greenschist phase of the middle-upper
Proterozoic Langshan Group in central Inner Mongolia. δ34S values for sulfides range from −3.1‰ to +37.3‰, and an apparent difference is noticed between vein sulfides and those in
bedded rocks. For example, δ34S values for bedded pyrite range from +10.6‰ to +20.0‰, while those for vein pyrite vary from −3.1‰ to +14.1‰. δ34S of bedded pyrrhotite is in the range +7.9‰–+23.5‰ in comparison with +6.5‰–+17.1‰ for vein pyrrhotite. The wide scatter
of δ34S and the enrichment of heavier sulfur indicate that sulfur may have been derived from H2S as a result of bacterial reduction of sulfates in the sea water. Sulfur isotopic composition also differs from deposit to
deposit in this area because of the difference in environment in which they were formed. The mobilization of bedded sulfides
in response to regional metamorphism and magmatic intrusion led to the formation of vein sulfides.
δ18O and δ13C of ore-bearing rocks and wall rocks are within the range typical of ordinary marine facies, with the exception of lower
values for ore-bearing marble at Huogeqi probably due to diopsidization and tremalitization of carbonate rocks.
Pb isotopic composition is relatively stable and characterized by lower radio-genetic lead. The age of basement rocks was
calculated to be about 23.9 Ma and ore-forming age 7.8 Ma.207Pb/204Pb−206Pb/204Pb and208Pb/204Pb−206Pb/204Pb plots indicate that Pb may probably be derived from the lower crust or upper mantle.
It is believed that the deposits in this region are related to submarine volcanic exhalation superimposed by later regional
metamorphism and magmatic intrusion. 相似文献
5.
Boron recycling in the continental crust of the central Andes from the Palaeozoic to Mesozoic, NW Argentina 总被引:4,自引:2,他引:2
Simone Kasemann Jörg Erzinger Gerhard Franz 《Contributions to Mineralogy and Petrology》2000,140(3):328-343
Whole-rock chemical composition and 11B/10B isotope ratios in tourmaline was investigated to study the geochemical recycling of boron during the evolution of the Andean
basement from the Palaeozoic to Mesozoic. In the basement (Cambrian to Ordovician high-grade paragneisses, migmatites and
orthogneisses, the Eocambrian Puncoviscana Formation, and Paleozoic-Mesozoic granitoid igneous rocks) whole-rock B contents
are generally below 100 ppm, but B contents of ˜1 wt% are found in cogenetic aplite and pegmatite dikes and in tourmaline–quartz
rocks. In the metasedimentary rocks, no systematic variation in B content because of metamorphic grade and no correlation
of B with other incompatible elements are apparent. Tourmalines from the high-grade metamorphic basement yield δ11B values ranging from −11.2 to −6.8‰ and isotope fractionation during migmatisation was small. Metamorphic tourmalines from
the Puncoviscana Formation have δ11B values between −6.3 and −5.8‰. The calculated (corrected for fractionation) δ11B values of −6 to −2‰ for the sedimentary protolith of the metamorphic basement indicate a continental B source with subordinate
marine input. Tourmalines from Palaeozoic and Mesozoic granitoids display an identical range of δ11B values from −12 to −5.3‰ and indicate a similarly homogeneous B source throughout time. Tourmalines from pegmatites and
tourmaline–quartz rocks record the average δ11B values of the parental granitic magma. We assume that B in the Palaeozoic and Mesozoic granitoids is derived from the local
metamorphic basement supporting the hypothesis that recycling of the lower Palaeozoic crust is the dominant process in granitic
magma formation from Palaeozoic to Mesozoic.
Received: 15 December 1999 / Accepted: 11 July 2000 相似文献
6.
The Janggun iron deposits, Republic of␣Korea, occur as lens-shaped magnesian skarn, magnetite and base-metal sulfide orebodies
developed in the Cambrian Janggun Limestone Formation. Mineralization stage of the deposits can be divided into two separate
events. The skarn stage (107 Ma) consists of magnetite, pyrrhotite, base-metal sulfides, carbonates and magnesian skarn minerals.
The hydrothermal stage (70 Ma) consists of base-metal sulfides, native bismuth, bismuthinite, tetrahedrite, boulangerite,
bournonite and stannite. Mineral assemblages, chemical compositions and thermodynamic considerations indicate that formation
temperatures, −log fs2 and −log fo2 values of ore fluids from the skarn stage were 433 to 345 °C, 8.1 to 9.7 bar and 29.4 to 31.6 bar, and the hydrothermal stage
was 245 to 315 °C, 10.4 to 13.2 bar and 33.6 to 35.4 bar, respectively. Thermochemical considerations indicate that the XCO2 during magnesian skarnization ranged from 0.06 to 0.09, and the activity of H+ presumably decreased when the fluids equilibrated with host dolomitic limestone which resulted in a pH change from about
6.1 to 7.8, and decreases in fo2 and fs2. The δ34S values of ore sulfides have a wide range from 3.2 to 11.6 ‰ (CDT). Calculated 34SH2
S values of ore fluids are 2.9 to 5.4 ‰ (skarn stage) and 8.7 to 13.5 ‰ (hydrothermal stage). These are interpreted to represent
an initial deep-seated, igneous source of sulfur which gave way to influence of oxidized sedimentary sulfur to hydrothermal
stage. The δ13C values of carbonates in ores range from −4.6 to −2.5 ‰ (PDB). It is likely that carbon in the ore fluids was a mixture of
deep-seated magmatic carbon and dissolved carbon of dolomitic limestone. The δ18OH2
O and δD values (SMOW) of water in the ore fluids were 14.7 to 1.8 and −85 to −73 ‰ during the skarn stage and 11.1 to −0.2
and −87 to −80 ‰ in the hydrothermal stage.
Received: 5 March 1997 / Accepted: 28 August 1997 相似文献
7.
The sulfur isotopic composition of sulfides and barite from hydrothermal deposits at the Valu Fa Ridge back-arc spreading
center in the southern Lau Basin has been investigated. Sulfide samples from the White Church area at the northern Valu Fa
Ridge have δ34S values averaging +3.8‰ (n= 10) for bulk sphalerite-chalcopyrite mineralization and +4.8‰ for pyrite (n= 10). Barite associated with the massive sulfides exhibits an average of +20.7‰ (n= 10). Massive sulfides from the active Vai Lili hydrothermal field at the central Valu Fa Ridge have much higher δ34S ratios averaging +8.0‰ for bulk sphalerite-chalcopyrite mineralization (n= 5), +9.3‰ for pyrite samples (n= 5), and +8.0‰ and +10.9‰ for a chalcopyrite and a sphalerite separate, respectively. The isotopic composition of barite
from the Vai Lili field is similar to that of barite from the White Church area and averages +21.0‰ (n= 8). Sulfide and barite samples from the Hine Hina area at the southern Valu Fa Ridge have δ34S values that are considerably lighter than those observed for samples from the other areas and average −4.9‰ for pyrite (n= 9), −4.0 and −5.7‰ for two samples of sphalerite-chalcopyrite intergrowth, and −3.4‰ for a single chalcopyrite separate.
The total spread in the isotopic composition of sulfides from Vai Lili and Hine Hina is more than 20‰ over a distance of less
than 30 km. The δ34S values of sulfides at Hine Hina are the lowest values so far reported for volcanic-hosted polymetallic massive sulfides
from the modern seafloor. Barite from the Hine Hina field also has unusually light sulfur with δ34S values of +16.1 to +16.7‰ (n= 5). Isotopic compositions of the sulfides at Hine Hina indicate a dramatic decrease in δ34S from ordinary magmatic values and, in the absence of biogenic sulfur and/or boiling, imply a unique 34S-depleted source of probable magmatic origin. Sulfide-barite mineralization in the Hine Hina area is associated with a distinctive
alteration assemblage consisting of cristobalite, pyrophyllite, kaolinite, opal-CT, talc, pyrite, native sulfur, and alunite.
Similar styles of alteration are typically known from high-sulfidation epithermal systems on land. Alunite-bearing, advanced
argillic alteration in the Hine Hina field confirms the role of acidic, volatile-rich fluids, and a δ34S value of +10.4‰ for the sulfur in the alunite is consistent with established kinetic isotope effects which accompany the
disproportionation of magmatic SO2 into H2S and H2SO4. The Hine Hina field occurs near the propagating tip of the Valu Fa back-arc spreading center (i.e., dominated by dike injections
and seafloor eruptions) and therefore may have experienced the largest contribution of magmatic volatiles of the three fields.
The sulfur isotopic ratios of the hydrothermal precipitates and the presence of a distinctive epithermal-like argillic alteration
in the Hine Hina field suggest a direct contribution of magmatic vapor to the hydrothermal system and support the concept
that magmatic volatiles may be an important component of some volcanogenic massive sulfide-forming hydrothermal systems.
Received: 16 January 1997 / Accepted: 28 October 1997 相似文献
8.
Stable isotope geochemistry and diagenetic mineralization associated with the Tono sandstone-type uranium deposit in Japan 总被引:5,自引:0,他引:5
The Tono sandstone-type uranium mine area, middle Honsyu, Japan is composed of Miocene lacustrine sedimentary rocks in the
lower part (18–22 Ma) and marine facies in the upper part (15–16 Ma). Calcite and pyrite occur as dominant diagenetic alteration
products in these Neogene sedimentary rocks. The characteristics of calcite and pyrite differ significantly between lacustrine
and marine facies. Abundant pyrite, calcite, organic matter, and small amounts of marcasite or pyrrhotite occur in the lacustrine
facies, whereas small amounts of calcite and framboidal pyrite, organic matter and no marcasite or pyrrhotite are found within
the marine units. The δ13C values of calcite in the lacustrine deposits are low (−19 to −6‰ PDB) but those in marine formation are high (−11 to +3‰).
This implies that the contribution of marine carbonate is larger in upper marine sedimentary rocks, and carbon in calcite
in the lower lacustrine formation was derived both from oxidation of organic matter and from dissolved marine inorganic carbon.
The δ34S values of framboidal pyrite in the upper marine formation are low (−14 to −8‰ CDT), indicating a small extent of bacterial
seawater sulfate reduction, whereas those of euhedral-subhedral pyrite in the lower lignite-bearing arkose sandstone are high
(+10 to +43‰), implying a large extent of closed-system bacterial seawater sulfate reduction. The δ34S and δ13C data which deviate from a negative correlation line toward higher δ13C values suggest methanogenic CO2 production. During diagenesis of the lacustrine unit, large amounts of euhedral-subhedral pyrite were formed, facilitated
by extensive bacterial reduction of seawater sulfate with concomitant oxidation of organic matter, and by hydrolysis reactions
of organic matter, producing CH4 and CO2. Uranium minerals (coffinite and uraninite) were also formed at this stage by the reduction of U6+ to U4+. The conditions of diagenetic alteration within the lacustrine deposits and uranium mineralization is characterized by low
Eh in which nearly equal concentrations of CH4 and HCO3
− existed and reduced sulfur species (H2S, HS−) are predominant among aqueous sulfur species, whereas diagenetic alteration of the marine formations was characterized by
a predominance of SO4
2− among dissolved sulfur species. Modern groundwater in the lacustrine formation has a low Eh value (−335 mV). Estimated and
measured low Eh values of modern and ancient interstitial waters in lacustrine environments indicate that a reducing environment
in which U4+ is stable has been maintained since precipitation of uranium minerals.
Received: 9 February 1996 / Accepted: 11 April 1997 相似文献
9.
Edward M. Ripley Nur Iskandar Taib Chusi Li Craig H. Moore 《Contributions to Mineralogy and Petrology》2007,154(1):35-54
Copper–nickel sulfide mineralization in the Partridge River Intrusion of the 1.1 Ga Duluth Complex is restricted primarily
to a 100 m thick zone near the base of the intrusion, which is heterogeneous at meter scales in terms of both sulfide contents
and rock types, which include dunite, melatroctolite, troctolite, leucotroctolite, gabbro, olivine gabbro, gabbronorite, and
rare norite. Olivine-rich troctolites and melatroctolites appear to have required mineral accumulation on a substrate, whereas
augite troctolite and gabbros are thought to have formed via in situ crystallization of magmas ranging in composition from
high-Al olivine tholeiite to high-Ti tholeiite. δ18O values of orthopyroxene-poor rocks in the Partridge River Intrusion range from 5.2 to 6.7‰. δ18O values of 6.7‰ are consistent with less than 20% contamination by high-18O metasedimentary country rock, either via devolatilization or local partial melting. Rocks with greater than ∼15% orthopyroxene,
gabbronorites, and norites, are characterized by δ18O values in excess of 6.9‰, and required the assimilation of larger amounts of siliceous country rocks. Sulfur isotopic values
in leucotroctolitic rocks that contain less than ∼400 ppm S and that overlie the basal zone range between −1.5 and 2‰, values
that are consistent with those of mantle-derived sulfur. In contrast, δ34S values in the basal zone range from −1.4 to 10.5‰, where the 34S-enriched samples require an input of sulfur from metasedimentary country rocks. δ34S values of the rocks in the basal zone correlate with variations in olivine Fo content but not with S abundance. The wide
range in δ34S values of rocks in the basal zone strongly suggests that magmas interacted with layers in the sedimentary country rocks
that were themselves characterized by variable sulfide contents and δ34S values. The S isotopic data suggest that the heterogeneity observed in the basal zone results from the emplacement of relatively
thin sheets of compositionally distinct magma. All rock types present in the basal zone can be produced as a result of variable
degrees of fractionation of a parental high-Al olivine tholeiite, followed by varying degrees of contamination of derivative
liquids by country rocks. The S-contamination process was essential for the development of Cu–Ni mineralization, and was restricted
to the earliest stages in the development of the Duluth Complex at a time when volatile species such as S and H2O, and low-T partial melts of country rocks, were available to magmas.
Electronic supplementary material The online version of this article (doi: ) contains supplementary material, which is available to authorized users. 相似文献
10.
Hamdy A. El Desouky Philippe Muchez Adrian J. Boyce Jens Schneider Jacques L. H. Cailteux Stijn Dewaele Albrecht von Quadt 《Mineralium Deposita》2010,45(8):735-763
The sediment-hosted stratiform Cu–Co mineralization of the Luiswishi and Kamoto deposits in the Katangan Copperbelt is hosted
by the Neoproterozoic Mines Subgroup. Two main hypogene Cu–Co sulfide mineralization stages and associated gangue minerals
(dolomite and quartz) are distinguished. The first is an early diagenetic, typical stratiform mineralization with fine-grained
minerals, whereas the second is a multistage syn-orogenic stratiform to stratabound mineralization with coarse-grained minerals.
For both stages, the main hypogene Cu–Co sulfide minerals are chalcopyrite, bornite, carrollite, and chalcocite. These minerals
are in many places replaced by supergene sulfides (e.g., digenite and covellite), especially near the surface, and are completely
oxidized in the weathered superficial zone and in surface outcrops, with malachite, heterogenite, chrysocolla, and azurite
as the main oxidation products. The hypogene sulfides of the first Cu–Co stage display δ34S values (−10.3‰ to +3.1‰ Vienna Canyon Diablo Troilite (V-CDT)), which partly overlap with the δ34S signature of framboidal pyrites (−28.7‰ to 4.2‰ V-CDT) and have ∆34SSO4-Sulfides in the range of 14.4‰ to 27.8‰. This fractionation is consistent with bacterial sulfate reduction (BSR). The hypogene sulfides
of the second Cu–Co stage display δ34S signatures that are either similar (−13.1‰ to +5.2‰ V-CDT) to the δ34S values of the sulfides of the first Cu–Co stage or comparable (+18.6‰ to +21.0‰ V-CDT) to the δ34S of Neoproterozoic seawater. This indicates that the sulfides of the second stage obtained their sulfur by both remobilization
from early diagenetic sulfides and from thermochemical sulfate reduction (TSR). The carbon (−9.9‰ to −1.4‰ Vienna Pee Dee
Belemnite (V-PDB)) and oxygen (−14.3‰ to −7.7‰ V-PDB) isotope signatures of dolomites associated with the first Cu–Co stage
are in agreement with the interpretation that these dolomites are by-products of BSR. The carbon (−8.6‰ to +0.3‰ V-PDB) and
oxygen (−24.0‰ to −10.3‰ V-PDB) isotope signatures of dolomites associated with the second Cu–Co stage are mostly similar
to the δ13C (−7.1‰ to +1.3‰ V-PDB) and δ18O (−14.5‰ to −7.2‰ V-PDB) of the host rock and of the dolomites of the first Cu–Co stage. This indicates that the dolomites
of the second Cu–Co stage precipitated from a high-temperature, host rock-buffered fluid, possibly under the influence of
TSR. The dolomites associated with the first Cu–Co stage are characterized by significantly radiogenic Sr isotope signatures
(0.70987 to 0.73576) that show a good correspondence with the Sr isotope signatures of the granitic basement rocks at an age
of ca. 816 Ma. This indicates that the mineralizing fluid of the first Cu–Co stage has most likely leached radiogenic Sr and
Cu–Co metals by interaction with the underlying basement rocks and/or with arenitic sedimentary rocks derived from such a
basement. In contrast, the Sr isotope signatures (0.70883 to 0.71215) of the dolomites associated with the second stage show
a good correspondence with the 87Sr/86Sr ratios (0.70723 to 0.70927) of poorly mineralized/barren host rocks at ca. 590 Ma. This indicates that the fluid of the
second Cu–Co stage was likely a remobilizing fluid that significantly interacted with the country rocks and possibly did not
mobilize additional metals from the basement rocks. 相似文献
11.
C. O'Reilly G. R. T. Jenkin M. Feely D. H. M. Alderton A. E. Fallick 《Contributions to Mineralogy and Petrology》1997,129(2-3):120-142
Fluid inclusions in granite quartz and three generations of veins indicate that three fluids have affected the Caledonian
Galway Granite. These fluids were examined by petrography, microthermometry, chlorite thermometry, fluid chemistry and stable
isotope studies. The earliest fluid was a H2O-CO2-NaCl fluid of moderate salinity (4–10 wt% NaCl eq.) that deposited late-magmatic molybdenite mineralised quartz veins (V1) and formed the earliest secondary inclusions in granite quartz. This fluid is more abundant in the west of the batholith,
corresponding to a decrease in emplacement depth. Within veins, and to the east, this fluid was trapped homogeneously, but
in granite quartz in the west it unmixed at 305–390 °C and 0.7–1.8 kbar. Homogeneous quartz δ18O across the batholith (9.5 ± 0.4‰n = 12) suggests V1 precipitation at high temperatures (perhaps 600 °C) and pressures (1–3 kbar) from magmatic fluids. Microthermometric data
for V1 indicate lower temperatures, suggesting inclusion volumes re-equilibrated during cooling. The second fluid was a H2O-NaCl-KCl, low-moderate salinity (0–10 wt% NaCl eq.), moderate temperature (270–340 °C), high δD (−18 ± 2‰), low δ18O (0.5–2.0‰) fluid of meteoric origin. This fluid penetrated the batholith via quartz veins (V2) which infill faults active during post-consolidation uplift of the batholith. It forms the most common inclusion type in
granite quartz throughout the batholith and is responsible for widespread retrograde alteration involving chloritization of
biotite and hornblende, sericitization and saussuritization of plagioclase, and reddening of K-feldspar. The salinity was
generated by fluid-rock interactions within the granite. Within granite quartz this fluid was trapped at 0.5–2.3 kbar, having
become overpressured. This fluid probably infiltrated the Granite in a meteoric-convection system during cooling after intrusion,
but a later age cannot be ruled out. The final fluid to enter the Granite and its host rocks was a H2O-NaCl-CaCl2-KCl fluid with variable salinity (8–28 wt% NaCl eq.), temperature (125–205 °C), δD (−17 to −45‰), δ18O (−3 to + 1.2‰), δ13CCO2 (−19 to 0‰) and δ34Ssulphate (13–23‰) that deposited veins containing quartz, fluorite, calcite, barite, galena, chalcopyrite sphalerite and pyrite (V3). Correlations of salinity, temperature, δD and δ18O are interpreted as the result of mixing of two fluid end-members, one a high-δD (−17 to −8‰), moderate-δ18O (1.2–2.5‰), high-δ13CCO2 (> −4‰), low-δ34Ssulphate (13‰), high-temperature (205–230 °C), moderate-salinity (8–12 wt% NaCl eq.) fluid, the other a low-δD (−61 to −45‰), low-δ18O (−5.4 to −3‰), low-δ13C (<−10‰), high-δ34Ssulphate (20–23‰) low-temperature (80–125 °C), high-salinity (21–28 wt% NaCl eq.) fluid. Geochronological evidence suggests V3 veins are late Triassic; the high-δD end-member is interpreted as a contemporaneous surface fluid, probably mixed meteoric
water and evaporated seawater and/or dissolved evaporites, whereas the low-δD end-member is interpreted as a basinal brine
derived from the adjacent Carboniferous sequence. This study demonstrates that the Galway Granite was a locus for repeated
fluid events for a variety of reasons; from expulsion of magmatic fluids during the final stages of crystallisation, through
a meteoric convection system, probably driven by waning magmatic heat, to much later mineralisation, concentrated in its vicinity
due to thermal, tectonic and compositional properties of granite batholiths which encourage mineralisation long after magmatic
heat has abated.
Received: 3 April 1996 / Accepted: 5 May 1997 相似文献
12.
Thomas Wagner Martin Okrusch Stefan Weyer Joachim Lorenz Yann Lahaye Heiner Taubald Ralf T. Schmitt 《Mineralium Deposita》2010,45(3):217-239
The Spessart district (SW Germany), located at the southwestern margin of the Permian Kupferschiefer basin in Central Europe,
hosts abundant stratabound and structurally controlled base metal mineralization. The mineralization styles identified are
(1) stratabound Cu-Pb-Zn-(Ag) ores in Zechstein sedimentary rocks, (2) structurally controlled Cu-As-(Ag) ores in Zechstein
sedimentary rocks, (3) crosscutting Co-Ni-(Bi)-As and Cu-Fe-As veins, (4) stratabound metasomatic Fe-Mn carbonate ores in
Zechstein dolomite, (5) barren barite veins, and (6) Fe-Mn-As veins in Permian rhyolites. Building on previous work that involved
mineralogical, textural, and chemical characterization of the major mineralization types, we have performed a comprehensive
sulfur isotope study that applied both conventional and novel laser-ablation multi-collector inductively coupled plasma mass
spectrometry techniques. The δ34S values of sulfide minerals from the different ore types are consistently negative and highly variable, in the range between
−44.5‰ and −3.9‰, whereas the δ34S values of barite are all positive in the range between 4.7‰ and 18.9‰. Remarkably, stratabound and structurally controlled
mineralization in Zechstein sedimentary rocks has the least negative δ34S values, whereas vein-type deposits have consistently more negative δ34S values. The observed pattern of sulfide δ34S values can be best interpreted in terms of fluid mixing at the basement-cover interface. Hydrothermal fluids originating
from the crystalline basement migrated upward along subvertical fault zones and were periodically injected into groundwaters
that were flowing in the post-Variscan sedimentary cover. These groundwaters had interacted with the Zechstein sedimentary
rocks, resulting in fluids characterized by elevated concentrations of reduced sulfur (with negative δ34S values) and alkaline pH. Repeated mixing between both chemically contrasting fluids caused rapid and efficient precipitation
of sulfide ore minerals in hydrothermal veins with highly variable but distinctly negative δ34S values. 相似文献
13.
Stable and radiogenic isotope composition of stratiform Cu–Co–Zn mineralization and associated sedimentary rocks within the Boléo district of the Miocene Santa Rosalía basin, Baja California Sur, constrains the evolution of seawater and hydrothermal fluids and the mechanisms responsible for sulfide and oxide deposition. Stable isotope geochemistry of limestone and evaporite units indicates a strong paleogeographic influence on the chemistry of the water column. Near-shore limestone at the base of the Boléo Formation is characterized by modified marine carbon (δ
13CPDB=−6.0 to +4.4‰) and oxygen (δ
18OSMOW=+19.5 to +26.2‰) isotope composition due to the influx of 13C- and 18O-depleted fluvial water. Sulfate sulfur isotope composition (δ
34SCDT=+17.21 to +22.3‰ and δ
18OSMOW=+10.7 to +13.1‰) for basal evaporite and claystone facies are similar to Miocene seawater. Strontium isotopes are less radiogenic than expected for Miocene seawater due to interaction with volcanic rocks. Low S/C ratios, high Mn contents and sedimentological evidence indicate the basin water column was oxidizing. The oxygenated basin restricted sulfide precipitation to within the sedimentary pile by replacement of early diagenetic framboidal pyrite and pore-space filling by Cu–Co–Zn sulfides to produce disseminated sulfides. Quartz–Mn oxide oxygen isotope geothermometry constrains mineralization temperature between 18 and 118°C. Sulfur isotopes indicate the following sources of sulfide: (1) bacterial sulfate reduction within the sedimentary pile produced negative δ
34S values (<−20‰) in framboidal pyrite; and (2) bacterial sulfate reduction at high temperature (80–118°C) within the sedimentary pile during the infiltration of the metal-bearing brines produced Cu–Co–Zn sulfides with negative, but close to 0‰, δ
34S values. Isotope modeling of fluid-rock reaction and fluid mixing indicates: (1) sedimentary and marine carbonates (δ
13C=−11.6 to −3.2‰ and δ
18O=+19.0 to +21.8‰) precipitated from basin seawater/pore water that variably mixed with isotopically depleted meteoric waters; and (2) hydrothermal calcite (δ
13C=−7.9 to +4.3‰ and δ
18O=+22.1 to +25.8‰) formed by dissolution and replacement of authigenic marine calcite by downward-infiltrating metalliferous brine and brine-sediment exchange, that prior to reaction with calcite, had mixed with isotopically depleted pore water. The downward infiltration of metalliferous brine is inferred from lateral and stratigraphic metal distributions and from the concentration of Cu sulfides along the upper contact of pyrite-bearing laminae. The co-existence and textural relationships among framboidal pyrite, base metal sulfides, carbonate and Mn–Fe oxides (including magnetite) within mineralized units are consistent with carbonate replacement and high-temperature bacterial reduction within the sedimentary pile occurring simultaneously below a seawater column under predominantly oxygenated conditions. 相似文献
14.
The Eastern Iberian Central System has abundant ore showings hosted by a wide variety of hydrothermal rocks; they include
Sn-W, Fe and Zn-(W) calcic and magnesian skarns, shear zone- and episyenite-hosted Cu-Zn-Sn-W orebodies, Cu-W-Sn greisens
and W-(Sn), base metal and fluorite-barite veins. Systematic dating and fluid inclusion studies show that they can be grouped
into several hydrothermal episodes related with the waning Variscan orogeny. The first event was at about 295 Ma followed
by younger pulses associated with Early Alpine rifting and extension and dated near 277, 150 and 100 to 20 Ma, respectively
(events II–IV). The δ18O-δD and δ34S studies of hydrothermal rocks have elucidated the hydrological evolution of these systems. The event I fluids are of mixed
origin. They are metamorphic fluids (H2O-CO2-CH4-NaCl; δ18O=4.7 to 9.3‰; δD ab.−34‰) related to W-(Sn) veins and modified meteoric waters in the deep magnesian Sn-W skarns (H2O-NaCl, 4.5–6.4 wt% NaCl eq.; δ18O=7.3–7.8‰; δD=−77 to −74‰) and epizonal shallow calcic Zn-(W) and Fe skarns (H2O-NaCl, <8 wt% NaCl eq.; δ18O=−0.4 to 3.4‰; δD=−75 to −58‰). They were probably formed by local hydrothermal cells that were spatially and temporally
related to the youngest Variscan granites, the metals precipitating by fluid unmixing and fluid-rock reactions. The minor
influence of magmatic fluids confirms that the intrusion of these granites was essentially water-undersaturated, as most of
the hydrothermal fluids were external to the igneous rocks. The fluids involved in the younger hydrothermal systems (events
II–III) are very similar. The waters involved in the formation of episyenites, chlorite-rich greisens, retrograde skarns and
phyllic and chlorite-rich alterations in the shear zones show no major chemical or isotopic differences. Interaction of the
hydrothermal fluids with the host rocks was the main mechanism of ore formation. The composition (H2O-NaCl fluids with original salinities below 6.2 wt% NaCl eq.) and the δ18O (−4.6 to 6.3‰) and δD (−51 to −40‰) values are consistent with a meteoric origin, with a δ18O-shift caused by the interaction with the, mostly igneous, host rocks. These fluids circulated within regional-scale convective
cells and were then channelled along major crustal discontinuities. In these shear zones the more easily altered minerals
such as feldspars, actinolite and chlorite had their δ18O signatures overprinted by low temperature younger events while the quartz inherited the original signature. In the shallower
portions of the hydrothermal systems, basement-cover fluorite-barite-base metal veins formed by mixing of these deep fluids
with downwards percolating brines. These brines are also interpreted as of meteoric origin (δ18O< ≈ −4‰; δD=−65 to −36‰) that leached the solutes (salinity >14 wt% NaCl eq.) from evaporites hosted in the post-Variscan
sequence. The δD values are very similar to most of those recorded by Kelly and Rye in Panasqueira and confirm that the Upper
Paleozoic meteoric waters in central Iberia had very negative δD values (≤−52‰) whereas those of Early Mesozoic age ranged
between −65 and −36‰.
Received: 9 June 1999 / Accepted: 19 January 2000 相似文献
15.
Summary The Dachang Sn-polymetallic ore district is one of the largest tin producing districts in China. Its origin has long been
in dispute between magmatic-hydrothermal replacement and submarine exhalative-hydrothermal origin. The Dachang ore district
comprises several types of ore deposits, including the Lamo magmatogenic skarn deposit near a granite intrusion, the Changpo-Tongkeng
bedded and vein-type sulfide deposit, and the Gaofeng massive sulfide deposit. Sulfide minerals from the Lamo skarn ores show
δ34S values in the range between −3 and +4‰ with a mean close to zero, suggesting a major magmatic sulfur source that likely
was the intrusive Longxianggai granite. Sulfide minerals from the Gaofeng massive ores show higher δ34S values between +5 and +12‰, whereas sulfide minerals from the Changpo-Tongkeng bedded ores display lighter δ34S values between −7 and −0.2‰. The difference in the sulfur isotope ranges in the two deposits can be interpreted by different
degrees of inorganic thermochemcial reduction of marine sulfate using a one-step batch separation fractionation model. Sulfur
isotopic compositions from the vein-type ores at Changpo-Tongkeng vary widely from −8 to +4‰, but most of the data cluster
around −2.9‰, which is close to that of bedded ores (−3.6‰). The sulfur in vein-type ores might be derived from bedded ores
or it represents a mixture of magmatic- and sedimentary-derived sulfur. Pb isotopic compositions of sulfide minerals in the
Dachang ore district reveal a difference between massive and bedded ores, with the massive ores displaying more radiogenic
Pb isotope ratios. Correlations of 206Pb/204Pb and 207Pb/204Pb or 208Pb/204Pb for the massive and bedded ores are interpreted as two-component mixing of Pb leached from sedimentary host rocks and from
deep-seated Precambrian basement rocks composed of metamorphosed volcano-sedimentary rocks. Pb isotopic compositions of sulfide
minerals from vein-type ores overlap with those of bedded sulfides. Similar to the sulfur, the lead in vein-type ores might
be derived from bedded ores. Skarn ores at Lamo show very limited variations in Pb isotopic compositions, which may reflect
a major magmatic-hydrothermal lead source. Helium isotope data of fluid inclusions trapped in sulfides indicate that He in
the massive and bedded ores has a different origin than He in fluorite of granite-related veins. The 3He/4He ratios of 1.2–2.9 Ra of fluid inclusions from sulfides at Gaofeng and Changpo-Tongkeng imply a contribution of mantle-derived
fluids. Overall our data support a submarine exhalative-hydrothermal origin for the massive and bedded ore types at Dachang.
Supplementary material to this paper is available in electronic form at
Appendix available as electronic supplementary material 相似文献
16.
Geology and geochemistry of telluride-bearing Au deposits in the Pingyi area, Western Shandong, China 总被引:2,自引:0,他引:2
Summary Telluride-bearing gold deposits of the Pingyi area, western Shandong, China, are located on the southeastern margin of the
North China Craton. There are two main types of deposits: (i) mineralized cryptoexplosive breccia, e.g., Guilaizhuang; and
(ii) stratified, finely-disseminated mineralization hosted in carbonate rocks, e.g., Lifanggou and Mofanggou deposits. In
Guilaizhuang, the cryptoexplosive breccia is formed within rocks of the Tongshi complex and Ordovician dolomite. The mineralization
is controlled by an E–W-trending listric fault. Stratified orebodies of the Lifanggou and Mofanggou deposits are placed along
a NE-trending, secondary detachment zone. They are hosted within dolomitic limestone, micrite and dolomite of the Early-Middle
Cambrian Changqing Group. The mineralization in the ore districts is considered to be related to the Early Jurassic Tongshi
magmatic complex that formed in a continental arc setting on the margin of the North China Craton. The host rocks are porphyritic
and consist predominantly of medium- to fine-grained diorite and pyroxene (hornblende)-bearing monzonite. SHRIMP U–Pb zircon
dating of diorites give a 206Pb/238U weighted mean age of 175.7 ± 3.8 Ma. This is interpreted as representing the crystallization age of the Tongshi magmatic
complex. Considering the contact relationships between the magmatic and host sedimentary rocks, as well as the genetic link
with the deposits, we conclude that this age is relevant also for the formation of mineralization in the Pingyi area. We hence
consider that the deposits formed in the Jurassic. The principal gold minerals are native gold, electrum and calaverite. Wall-rock
alteration comprises pyritization, fluoritization, silicification, carbonatization and chloritization. Fluid inclusion studies
indicate that all the analyzed inclusions are of two-phase vapor–liquid NaCl–H2O type. Homogenization temperatures of the fluid inclusions vary from 103 °C to 250 °C, and the ice melting temperatures range
from −2.5 °C to −13.5 °C, corresponding to a salinity range of 4.65 to 17.26 wt.% NaCl equiv. The δ34S values of pyrite associated with gold mineralization exhibit a narrow range of −0.71 to + 2.99‰, implying that the sulfur
was probably derived from the mantle and/or dioritic magma. The δ13CPDB values of the fluid inclusions in calcite range from −7.3 to 0.0‰. The δ18OSMOW values of vein quartz and calcite range from 11.5 to 21.5‰, corresponding to δ18Ofluid values of −1.1 to 10.9‰; δD values of the fluid inclusions vary between −70 and −48‰. The isotope data for all three deposits
suggest mixing of ore-forming fluids derived from the mantle and/or magma with different types of fluids at shallow levels.
Pressure release and boiling of the fluids, as well as fluid-rock interaction (Lifanggou and Mofanggou) and mixing of magmatically-derived
fluids with meteoritic waters (Guilaizhuang) played an important role in the ore-forming processes. 相似文献
17.
Åke Fagereng Chris Harris Mandy La Grange Gary Stevens 《Contributions to Mineralogy and Petrology》2008,155(1):63-78
The Vredefort dome in the Kaapvaal Craton was formed as a result of the impact of a large meteorite at 2.02 Ga. The central
core of Archaean granitic basement rocks is surrounded by a collar of uplifted and overturned strata of the Witwatersrand
Supergroup, exposing a substantial depth section of the Archaean crust. Orthogneisses of the core show little variation in
whole-rock δ
18O value, with the majority being between 8 and 10‰, with a mean of 9.2‰ (n = 35). Quartz and feldspar have per mil differences that are consistent with O-isotope equilibrium at high temperatures,
suggesting minimal interaction with fluids during subsequent cooling. These data refute previous suggestions that the Outer
Granite Gneiss (OGG) and Inlandsee Leucogranofels (ILG) of the core represent middle and lower crust, respectively. Granulite-facies
greenstone remnants from the ILG have δ
18O values that are on average 1.5‰ higher than the ILG host rocks and are unlikely, therefore, to represent the residuum from
the partial melting event that formed the host rock. Witwatersrand Supergroup sedimentary rocks of the collar, which were
metamorphosed at greenschist-to amphibolite-facies conditions, generally have lower δ
18O values than the core rocks with a mean value for metapelites of 7.7‰ (n = 45). Overall, through an ∼20 km thick section of crust, there is a general increase in whole-rock δ
18O value with increasing depth. This is the reverse of what is normal in the crust, largely because the collar rocks have δ
18O values that are unusually low in comparison with metamorphosed sedimentary rocks worldwide. The collar rocks have δD values ranging from −35 to −115‰ (average −62‰, n = 29), which are consistent with interaction with water of meteoric origin, having a δD of about −25 to −45‰. We suggest that fluid movement through the collar rocks was enhanced by impact-induced secondary permeability
in the dome structure.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
18.
A set of sheeted quartz veins cutting 380 Ma monzogranite at Sandwich Point, Nova Scotia, Canada, provide an opportunity to
address issues regarding fluid reservoirs and genesis of intrusion-related gold deposits. The quartz veins, locally with arsenopyrite
(≤5%) and elevated Au–(Bi–Sb–Cu–Zn), occur within the reduced South Mountain Batholith, which also has other zones of anomalous
gold enrichment. The host granite intruded (P = 3.5 kbars) Lower Paleozoic metaturbiditic rocks of the Meguma Supergroup, well known for orogenic vein gold mineralization.
Relevant field observations include the following: (1) the granite contains pegmatite segregations and is cut by aplitic dykes
and zones (≤1–2 m) of spaced fracture cleavage; (2) sheeted veins containing coarse, comb-textured quartz extend into a pegmatite
zone; (3) arsenopyrite-bearing greisens dominated by F-rich muscovite occur adjacent the quartz veins; and (4) vein and greisen
formation is consistent with Riedel shear geometry. Although these features suggest a magmatic origin for the vein-forming
fluids, geochemical studies indicate a more complex origin. Vein quartz contains two types of aqueous fluid inclusion assemblages
(FIA). Type 1 is a low-salinity (≤3 wt.% equivalent NaCl) with minor CO2 (≤2 mol%) and has T
h = 280–340°C. In contrast, type 2 is a high-salinity (20–25 wt.% equivalent NaCl), Ca-rich fluid with T
h = 160–200°C. Pressure-corrected fluid inclusion data reflect expulsion of a magmatic fluid near the granite solidus (650°C)
that cooled and mixed with a lower temperature (400°C), wall rock equilibrated, Ca-rich fluid. Evidence for fluid unmixing,
an important process in some intrusion-related gold deposit settings, is lacking. Stable isotopic (O, D, S) analyses for quartz,
muscovite and arsenopyrite samples from vein and greisens indicate the following: (1) δ18Oqtz = +11.7‰ to 17.8‰ and δ18Omusc = +10.7‰ to +11.2‰; (2) δDmusc = −44‰ to−54‰; and (3) δ34Saspy = +7.8‰ to +10.3‰. These data are interpreted, in conjunction with fluid inclusion data, to reflect contamination of a magmatic-derived
fluid (d18OH2O {\delta^{{{18}}}}{{\hbox{O}}_{{{{\rm{H}}_{{2}}}{\rm{O}}}}} ≤ +10‰) by an external fluid (d18OH2O {\delta^{{{18}}}}{{\hbox{O}}_{{{{\rm{H}}_{{2}}}{\rm{O}}}}} ≥ +15‰), the latter having equilibrated with the surrounding metasedimentary rocks. The δ34S data are inconsistent with a direct igneous source based on other studies for the host intrusion (d18OH2O {\delta^{{{18}}}}{{\hbox{O}}_{{{{\rm{H}}_{{2}}}{\rm{O}}}}} = +5‰) and are, instead, consistent with an external reservoir for sulphur based on δ34SH2S data for the surrounding metasedimentary rocks. Divergent fluid reservoirs are also supported by analyses of Pb isotopes
for pegmatitic K-feldspar and vein arsenopyrite. Collectively the data indicate that the vein- and greisen-forming fluids
had a complex origin and reflect both magmatic and non-magmatic reservoirs. Thus, although the geological setting suggests
a magmatic origin, the geochemical data indicate involvement of multiple reservoirs. These results suggest multiple reservoirs
for this intrusion-related gold deposit setting and caution against interpreting the genesis of intrusion-related gold deposit
mineralization in somewhat analogous settings based on a limited geochemical data set. 相似文献
19.
T. Oberthür T. G. Blenkinsop U. F. Hein M. Höppner A. Höhndorf T. W. Weiser 《Mineralium Deposita》2000,35(2-3):138-156
In the Mazowe area some 40 km NW of Harare in Zimbabwe, gold mineralization is hosted in a variety of lithologies of the
Archean Harare-Bindura-Shamva greenstone belt, in structures related to the late Archean regional D2/3 event. Conspicuous
mineralzogical differences exist between the mines; the mainly granodiorite-hosted workings at Mazowe mine are on pyrite-rich
reefs, mines of the Bernheim group have metabasalt host rocks and are characterized by arsenopyrite-rich ores, and Stori's
Golden Shaft and Alice mine, both in metabasalts, work sulfide-poor quartz veins. In contrast to the mineralogical diversity,
near-identical fluid inventories were found at the different mines. Both H2O-CO2-CH4 fluids of low salinity, and highly saline fluids are present and are regarded to indicate fluid mixing during the formation
of the deposits. Notably, these fluid compositions in the Mazowe gold field markedly contrast to ore fluids “typical” of Archean
mesothermal gold deposits on other cratons. Stable isotope compositions of quartz from the various deposits (δ18O=10.8 to 13.2‰ SMOW), calcite (δ18O=9.5 to 11.9‰ SMOW and δ13C=−3.2 to −8.0‰ PDB), inclusion water (δD=−28 to −40‰ SMOW) and sulfides (δ34S=1.3 to 3.2‰ CDT) are uniform within the range typical for Archean lode gold deposits worldwide. The fluid and stable isotope
compositions support the statement that the mineralization in the Mazowe gold field formed from relatively reduced fluids
with a “metamorphic” signature during a single event of gold mineralization. Microthermometric data further indicate that
the deposits formed in the PT range of 1.65–2.3 kbar and 250–380 °C. Ages obtained by using the Sm/Nd and Rb/Sr isotope systems on scheelites are 2604 ± 84 Ma
for the mineralization at Stori's Golden Shaft mine, and 2.40 ± 0.20 Ga for Mazowe mine. The Archean age at Stori's is regarded
as close to the true age of gold mineralization in the area, whereas the Proterozoic age at Mazowe mine probably reflects
later resetting.
Received: 30 September 1998 / Accepted: 17 August 1999 相似文献
20.
Sulfur isotopic composition of sulfides at the Mangazeya silver deposit,Eastern Sakha-Yakutia,Russia
The succession of the formation of ore zones and sulfur isotope ratio of sulfides at the Mangazeya Ag deposit have been studied.
The deposit is located in the Nyuektame Fault Zone in the eastern limb of the Endybal Anticline. The ore zones are hosted
in the Middle Carboniferous to Middle Jurassic terrigenous sequences of the Verkhoyansk Complex intruded by the Endybal subvolcanic
stock and felsic and mafic dikes. Three ore stages are distinguished: (I) gold-rare metal, (II) cassiterite-sulfide, and (III)
silver-base-metal. Products of these stages are spatially isolated. The δ34S of sulfides ranges from −6.4 to +8.0‰. In the sulfides of the gold-rare metal assemblage, this value varies from −1.8 to
+4.7‰; in the sulfides of the cassiterite-sulfide stage, −6.4 to +6.6‰; and in the sulfides of the silver-base-metal assemblage,
-5.6 to +8.0‰. A sulfur isotope thermometer indicates the temperature of mineral deposition at 315–415°C for the first stage
and 125–280°C for the third stage. Possible causes of variable sulfur isotopic composition in sulfides are discussed. The
data on the sulfur isotope ratio is interpreted in terms of involvement of magmatic fluid (δ34S ∼ 0) in the mineralizing process along with low-temperature fluid taking sulfur from host rocks (δ34S ≫ 0). Boiling and mixing of magmatic fluid with heated meteoric water were important at the last stage of the deposit formation. 相似文献