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20 pages, 4883 KiB

Open AccessArticle

Massive Sulfide Ores in the Iberian Pyrite Belt: Mineralogical and Textural Evolution

by Gabriel R. Almodóvar, Lola Yesares, Reinaldo Sáez, Manuel Toscano, Felipe González and Juan Manuel Pons

Minerals 2019, 9(11), 653; https://doi.org/10.3390/min9110653 - 24 Oct 2019

Cited by 38 | Viewed by 12016

Abstract

The Iberian Pyrite Belt (IPB) is recognized as having one of the major concentrations of volcanogenic massive sulfide (VMS) deposits on Earth. Original resources of about 2000 Mt of massive sulfides have been reported in the province. Recent classifications have considered the IPB [...] Read more.

The Iberian Pyrite Belt (IPB) is recognized as having one of the major concentrations of volcanogenic massive sulfide (VMS) deposits on Earth. Original resources of about 2000 Mt of massive sulfides have been reported in the province. Recent classifications have considered the IPB deposits as the bimodal siliciclastic subtype, although major differences can be recognized among them. The main ones concern the hosting rocks. To the north, volcanic and volcaniclastic depositional environments predominate, whereas to the south, black shale-hosted VMS prevail. The mineral composition is quite simple, with pyrite as the main mineral phase, and sphalerite, galena, and chalcopyrite as major components. A suite of minor minerals is also present, including arsenopyrite, tetrahedrite–tennantite, cobaltite, Sb–As–Bi sulfosalts, gold, and electrum. Common oxidized phases include magnetite, hematite, cassiterite, and barite. The spatial relationship between all these minerals provides a very rich textural framework. A careful textural analysis reported here leads to a general model for the genetic evolution of the IPB massive sulfides, including four main stages: (1) Sedimentary/diagenetic replacement process on hosting rocks; (2) sulfides recrystallization at rising temperature; (3) metal distillation and sulfides maturation related to late Sb-bearing hydrothermal fluids; and (4) metal remobilization associated with the Variscan tectonism. The proposed model can provide new tools for mineral exploration as well as for mining and metallurgy. Full article

(This article belongs to the Special Issue Massive Sulfide Deposits all around the World)

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17 pages, 5198 KiB

Open AccessArticle

Geology, Fluid Inclusions and Stable Isotopes of the Xialiugou Polymetallic Deposit in North Qilian, Northwest China: Constraints on its Metallogenesis

by Yongjun Shao, Huajie Tan, Guangxiong Peng, Jiandong Zhang, Jianzhou Chen, Qiaomei Chen and Yu Zhang

Minerals 2019, 9(8), 478; https://doi.org/10.3390/min9080478 - 7 Aug 2019

Cited by 2 | Viewed by 3762

Abstract

The Xialiugou polymetallic deposit is located in the North Qilian Orogenic Belt, Northwest China, of which the main ore-bearing strata are the Middle Cambrian Heicigou Group. The mineralization is zoned with “black” orebodies (galena–sphalerite), which are stratigraphically above the “yellow” orebodies (pyrite–chalcopyrite–tennantite) at [...] Read more.

The Xialiugou polymetallic deposit is located in the North Qilian Orogenic Belt, Northwest China, of which the main ore-bearing strata are the Middle Cambrian Heicigou Group. The mineralization is zoned with “black” orebodies (galena–sphalerite), which are stratigraphically above the “yellow” orebodies (pyrite–chalcopyrite–tennantite) at the lower zone, corresponding to the alteration assemblages of quartz–sericite in the ore-proximal zone and chlorite in the ore-distal zone. The Xialiugou mineralization can be divided into three stages: (1) Stage I (pyrite); (2) Stage II (chalcopyrite–tennantite–sphalerite); and (3) Stage III (galena–sphalerite). Fluid inclusions data indicate that the physicochemical conditions that lead to ore formation were the medium–low temperature (157–350 °C) and low salinity (0.17–6.87 wt % NaCl_eqv), and that the ore-forming temperature tended to decrease with the successive mineralization processes. Taking the H–O isotopic compositions (δD_V-SMOW = −51.0‰ to −40.5‰, δ¹⁸O_H2O = −0.4‰ to 8.6‰) into consideration, the ore-forming fluids were most likely derived from seawater with a small amount of magmatic- and meteoric-fluids input. In addition, the combined S (−3.70‰ to 0.10‰) and Pb isotopic (²⁰⁶Pb/²⁰⁴Pb = 18.357 to 18.422, ²⁰⁷Pb/²⁰⁴Pb = 15.615 to 15.687, ²⁰⁸Pb/²⁰⁴Pb = 38.056 to 38.248) data of pyrite indicate that the ore-bearing volcanic rocks may be an important source of ore-forming materials. Finally, we inferred that the Xialiugou deposit shares similarities with the most important volcanogenic massive sulfide (VMS) deposits (Baiyinchang ore field) in China and typical “black ore” type VMS deposits worldwide. Full article

(This article belongs to the Special Issue Massive Sulfide Deposits all around the World)

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27 pages, 5446 KiB

Open AccessArticle

Coupling Mineralogy, Textures, Stable and Radiogenic Isotopes in Identifying Ore-Forming Processes in Irish-Type Carbonate-Hosted Zn–Pb Deposits

by Lola Yesares, Drew A. Drummond, Steven P. Hollis, Aileen L. Doran, Julian F. Menuge, Adrian J. Boyce, Robert J. Blakeman and John H. Ashton

Minerals 2019, 9(6), 335; https://doi.org/10.3390/min9060335 - 29 May 2019

Cited by 10 | Viewed by 7509

Abstract

Irish-type deposits comprise carbonate-hosted sphalerite- and galena-rich lenses concentrated near normal faults. We present new data from the Tara Deep resource and overlying mineralization, at Navan, and the Island Pod deposit and associated Main zone orebodies, at Lisheen. Tara Deep mineralization predominantly replaces [...] Read more.

Irish-type deposits comprise carbonate-hosted sphalerite- and galena-rich lenses concentrated near normal faults. We present new data from the Tara Deep resource and overlying mineralization, at Navan, and the Island Pod deposit and associated Main zone orebodies, at Lisheen. Tara Deep mineralization predominantly replaces Tournasian micrites and subordinate Visean sedimentary breccias. The mineralization is mainly composed of sphalerite, galena, marcasite and pyrite. A range of Cu- and Sb-bearing minerals occur as minor phases. At Tara Deep, paragenetically early sulfides exhibit negative δ³⁴S values, with later phases displaying positive δ³⁴S values, indicating both bacterial sulfate reduction (BSR) and hydrothermal sulfur sources, respectively. However, maximum δ³⁴S values are heavier (25‰) than in the Main Navan orebody (17‰). These mineralogical and isotopic features suggest that Tara Deep represents near-feeder mineralization relative to the Navan Main orebody. The subeconomic mineralization hosted in the overlying Thin Bedded Unit (TBU) comprises sphalerite replacing framboidal pyrite, both exhibiting negative δ³⁴S values (−37.4 to −8.3‰). These features indicate a BSR source of sulfur for TBU mineralization, which may represent seafloor exhalation of mineralizing fluids that formed the Tara Deep orebody. The Island Pod orebody, at Lisheen, shows a mineralogical paragenetic sequence and δ³⁴S values broadly similar to other Lisheen orebodies. However, the lack of minor Cu, Ni, and Sb minerals suggests a setting more distal to hydrothermal metal feeder zones than the other Lisheen orebodies. Pb isotope data indicate a very homogeneous Lower Palaeozoic Pb source for all Navan orebodies. Lower Palaeozoic metal sources are also inferred for Lisheen, but with variations both within and between orebodies. Carbon and oxygen isotopic variations at Navan and Lisheen appear to result from fluid-carbonate rock buffering. The emerging spectrum of mineralogical and isotopic variations define proximal to distal characteristics of Irish-type systems and will assist in developing geochemical vectoring tools for exploration. Full article

(This article belongs to the Special Issue Massive Sulfide Deposits all around the World)

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25 pages, 11633 KiB

Open AccessArticle

He-Ar Isotopes and Trace Gas Compositions of Fluid Inclusions in Massive Sulphides from the Yushui Copper-Polymetallic Deposit, South China: Metallogenic Implications

by Yi Huang, Zhongwei Wu, Xiaoming Sun, Yan Wang, Guiyong Shi, Wei Zhai and Yao Guan

Minerals 2019, 9(5), 258; https://doi.org/10.3390/min9050258 - 29 Apr 2019

Cited by 3 | Viewed by 4411

Abstract

The Yushui ore deposit, located in the middle section of the Yong’an-Meixian Hercynian depression, is a medium-sized Cu-polymetallic massive sulphide deposit in Eastern Guangdong Province, South China. This deposit is characterized by unusually high copper grade (up to 50–60 wt. % Cu). Other [...] Read more.

The Yushui ore deposit, located in the middle section of the Yong’an-Meixian Hercynian depression, is a medium-sized Cu-polymetallic massive sulphide deposit in Eastern Guangdong Province, South China. This deposit is characterized by unusually high copper grade (up to 50–60 wt. % Cu). Other metallic elements, such as lead, zinc and silver, are also economically important in the Yushui ore bodies. The aim of this study was to apply N₂–Ar–He systematics, together with organic gases (light-hydrocarbon tracers), to constrain the origin and evolution of ore-forming fluids. The helium-argon isotopes and trace gas compositions of fluid inclusions trapped within metal sulphide minerals were measured for a number of bonanza ores from the Yushui deposit. The noble gas concentrations in the studied samples vary over one to two orders of magnitude (⁴He: 2.27–160.00 × 10⁻⁵ cm³ STP g⁻¹; ³He: 0.53–34.88 × 10⁻¹² cm³ STP g⁻¹; ⁴⁰Ar: 6.28–37.82 × 10⁻⁷ cm³ STP g⁻¹; ³⁶Ar: 1.25–10.40 × 10⁻⁹ cm³ STP g⁻¹). Our data show a narrow range of ³He/⁴He ratios from 0.006 to 0.056 R_a (~0.026 R_a on average, n = 8), which are considerably lower than the modern atmospheric end-member value; whereas the ⁴⁰Ar/³⁶Ar ratios (ranging from 333.76 to 501.68, with an average of 397.53) are significantly greater than that of air-saturated water. Most of the bornite samples have somewhat higher ³He/⁴He ratios of trapped fluids when compared to chalcopyrite. Overall, these He-Ar results are well within the range of crustal reservoir, thus implying a predominantly crustal source (originated from Caledonian basement) for ore-forming solutions, with little contribution from mantle-derived fluids. Analysis of the N₂–Ar–He composition in Cu-rich sulphides indicates that the Yushui ore-forming fluids were probably derived from formation water (or basinal hot brines). Moreover, organic gas species identified in sulphide-hosted fluid inclusions are mainly composed of C₁–C₄ alkanes, while the concentrations of unsaturated olefins and aromatic hydrocarbons are very low. In particular, most chalcopyrite samples with relatively low ³He^/4He ratios (0.006–0.016 R_a) and ⁴⁰Ar*/⁴He values (0.0002–0.0012) are generally characterized by very high CO₂/CH₄ ratios (~60–102). All these suggest that main-stage Cu-Ag metallogenic processes might have not been affected by high-temperature magmatic activities or superimposed by strong metamorphic overprinting, although some chalcopyrite-rich ores appear to be influenced by later stage hydrothermal processes. In summary, neither magmatic input nor convecting seawater has played an important role in the formation of Yushui copper-polymetallic deposit. The massive sulphide ore bodies were products of water–rock interaction between metal-bearing basinal brines and the host sedimentary strata. Full article

(This article belongs to the Special Issue Massive Sulfide Deposits all around the World)

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31 pages, 5089 KiB

Open AccessFeature PaperArticle

The Moroccan Massive Sulphide Deposits: Evidence for a Polyphase Mineralization

by Abderrahim Essaifi, Kathryn Goodenough, Fernando Tornos, Abdelhak Outigua, Abdelmalek Ouadjou and Lhou Maacha

Minerals 2019, 9(3), 156; https://doi.org/10.3390/min9030156 - 6 Mar 2019

Cited by 10 | Viewed by 5594

Abstract

This work provides an overview of the geological, geochemical, and metallogenic data available up to date on the Moroccan massive sulphide deposits, including some new results, and then discusses the evidences for the epigenetic and syngenetic hypotheses. All of the ore deposits are [...] Read more.

This work provides an overview of the geological, geochemical, and metallogenic data available up to date on the Moroccan massive sulphide deposits, including some new results, and then discusses the evidences for the epigenetic and syngenetic hypotheses. All of the ore deposits are located within a crustal block located at the intersection between two major shear zones and are characterized by a sustained and long-lived magmatic activity. The ore deposits are located within second-order shear zones, which played an important role in controlling the geometry of the mineralization. The mineralization lacks the unequivocal textural and structural features that are indicative of a sedimentary or diagenetic origin, and a syntectonic to late-tectonic pyrite-rich assemblage is superimposed on an earlier, pretectonic to syntectonic pyrrhotite-rich mineralization. Each deposit has a distinctive pyrrhotite sulfur isotopic signature, while the sulfur isotopic signature of pyrite is similar in all deposits. Lead isotopes suggest a shift from a magmatic source during the pyrrhotite-rich mineralization to a source that is inherited from the host shales during the pyrite-rich mineralization. The O/H isotopic signatures record a predominance of fluids of metamorphic derivation. These results are consistent with a model in which an earlier pyrrhotite-rich mineralization, which formed during transtension, was deformed and then remobilized to pyrite-rich mineralization during transpression. Full article

(This article belongs to the Special Issue Massive Sulfide Deposits all around the World)

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38 pages, 72927 KiB

Open AccessFeature PaperArticle

Mineralogical Features of Ore Diagenites in the Urals Massive Sulfide Deposits, Russia

by Valeriy V. Maslennikov, Nuriya R. Ayupova, Nataliya P. Safina, Aleksandr S. Tseluyko, Irina Yu. Melekestseva, Ross R. Large, Richard J. Herrington, Vasiliy A. Kotlyarov, Ivan A. Blinov, Svetlana P. Maslennikova and Svetlana G. Tessalina

Minerals 2019, 9(3), 150; https://doi.org/10.3390/min9030150 - 28 Feb 2019

Cited by 18 | Viewed by 8696

Abstract

In weakly metamorphosed massive sulfide deposits of the Urals (Dergamysh, Yubileynoe, Yaman-Kasy, Molodezhnoe, Valentorskoe, Aleksandrinskoe, Saf’yanovskoe), banded sulfides (ore diagenites) are recognized as the products of seafloor supergene alteration (halmyrolysis) of fine-clastic sulfide sediments and further diagenesis leading to the formation of authigenic [...] Read more.

In weakly metamorphosed massive sulfide deposits of the Urals (Dergamysh, Yubileynoe, Yaman-Kasy, Molodezhnoe, Valentorskoe, Aleksandrinskoe, Saf’yanovskoe), banded sulfides (ore diagenites) are recognized as the products of seafloor supergene alteration (halmyrolysis) of fine-clastic sulfide sediments and further diagenesis leading to the formation of authigenic mineralization. The ore diagenites are subdivided into pyrrhotite-, chalcopyrite-, bornite-, sphalerite-, barite- and hematite-rich types. The relative contents of sphalerite-, bornite- and barite-rich facies increases in the progression from ultramafic (=Atlantic) to bimodal mafic (=Uralian) and bimodal felsic (=Baymak and Rudny Altay) types of massive sulfide deposits. The ore diagenites have lost primary features within the ore clasts and dominantly exhibit replacement and neo-formed nodular microtextures. The evolution of the mineralogy is dependent on the original primary composition, sizes and proportions of the hydrothermal ore clasts mixed with lithic serpentinite and hyaloclastic volcanic fragments together with carbonaceous and calcareous fragments. Each type of ore diagenite is characterized by specific rare mineral assemblages: Cu–Co–Ni sulfides are common in pyrrhotite-rich diagenites; tellurides and selenides in chalcopyrite-rich diagenites; minerals of the germanite group and Cu–Ag and Cu–Sn sulfides in bornite-rich diagenites; abundant galena and sulfosalts in barite- and sphalerite-rich diagenites and diverse tellurides characterize hematite-rich diagenites. Native gold in variable amounts is typical of all types of diagenites. Full article

(This article belongs to the Special Issue Massive Sulfide Deposits all around the World)

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31 pages, 12326 KiB

Open AccessArticle

Chlorite-White Mica Pairs’ Composition as a Micro-Chemical Guide to Fingerprint Massive Sulfide Deposits of the Bathurst Mining Camp, Canada

by Azam Soltani Dehnavi, Christopher R. M. McFarlane, David R. Lentz, Sean H. McClenaghan and James A. Walker

Minerals 2019, 9(2), 125; https://doi.org/10.3390/min9020125 - 21 Feb 2019

Cited by 12 | Viewed by 5812

Abstract

The compositions of phyllosilicates, with a focus on fluid-mobile elements, were evaluated as a means to fingerprint the Middle Ordovician metamorphosed (greenschist facies) volcanogenic massive sulfide deposits of the Bathurst Mining Camp (BMC), Canada. Ninety-five drill-core samples from six of the major deposits [...] Read more.

The compositions of phyllosilicates, with a focus on fluid-mobile elements, were evaluated as a means to fingerprint the Middle Ordovician metamorphosed (greenschist facies) volcanogenic massive sulfide deposits of the Bathurst Mining Camp (BMC), Canada. Ninety-five drill-core samples from six of the major deposits of the Bathurst Mining Camp (Brunswick No. 12, Heath Steele B zone, Halfmile Lake Deep zone, Key Anacon East zone, Louvicourt, and Restigouche) were analyzed using electron microprobe and laser ablation inductively coupled plasma-mass spectrometry. Typically, phyllosilicates (chlorite, white mica, and to a lesser extent biotite) are ubiquitous phases in the host rocks of the massive sulfide deposits of the BMC. Electron microprobe analysis results show a wide compositional variation in chlorite and white mica. Laser ablation inductively coupled plasma-mass spectrometry (LA-ICP-MS) analysis was performed to measure fluid-mobile elements, showing that Tl is distinctly enriched in all white mica (up to 719 ppm) relative to chlorite (up to 50.1 ppm). Chlorite hosts Sn (up to 4600 ppm), Hg (up to 7.3 ppm), Sb (up to 35.4 ppm), As (up to 1320 ppm), In (up to 307 ppm), Cd (up to 83.2 ppm), and Se (up to 606 ppm). White mica hosts Sn (up to 1316 ppm), Hg (up to 93 ppm), Sb (up to 1630 ppm), As (up to 14,800 ppm), In (up to 1186 ppm), Cd (up to 98 ppm), and Se (up to 38.8 ppm). Limited LA-ICP-MS analysis on biotite indicates a higher overall concentration of Tl (mean = 14.6 ppm) relative to co-existing white mica (mean = 2.18 ppm). On average, biotite is also more enriched in Hg, Sn, and Ba relative to chlorite and white mica. Laser Ablation ICP-MS profiles of chlorite, white mica, and biotite demonstrate smooth time-dependent variations diagnostic of structural substitution of these elements. Compositional variation of chlorite-white mica pairs presented in the current study shows systematic variations as a function of distance from the mineralized horizons. This highlights the potential to use trace-element signatures in these phyllosilicate pairs to identify proximal (chlorite) and distal (white mica) footprints for volcanogenic massive sulfides exploration. Full article

(This article belongs to the Special Issue Massive Sulfide Deposits all around the World)

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14 pages, 1980 KiB

Open AccessArticle

Basin Evolution and Massive Sulfide Deposition at Rammelsberg (Germany): Updating the Subsidence Analysis

by Carmen Moreno, Felipe González and Reinaldo Sáez

Minerals 2019, 9(1), 45; https://doi.org/10.3390/min9010045 - 14 Jan 2019

Cited by 1 | Viewed by 4578

Abstract

The Rammelsberg sulfide deposit is classically considered as a SEDEX-type deposit. The origin of SEDEX-type massive sulfides links with the evolution of their hosting basins. They frequently constitute the source for the metal-enriched basinal brines transported afterwards as mineralizing hydrothermal fluids. This study [...] Read more.

The Rammelsberg sulfide deposit is classically considered as a SEDEX-type deposit. The origin of SEDEX-type massive sulfides links with the evolution of their hosting basins. They frequently constitute the source for the metal-enriched basinal brines transported afterwards as mineralizing hydrothermal fluids. This study revisits previous data concerning the analysis of the basin that hosts the Rammelsberg deposit, the Goslar basin, updating its subsidence analysis and providing new tectonic and total subsidence curves from two different paleogeographic locations: the depocenter and the basin margin. The basin evolution is defined by five stages depicting different subsidence intensity and mechanisms for each of these locations. The stratigraphic position of Rammelsberg coincides with a drastic change in the basin evolution. A rapid tectonic subsidence event is proposed as a trigger mechanism for hydrothermal activity. The paleogeographic location and the relation between supply of mineralizing fluids and sedimentation rate were critical for the concentration or dissemination of sulfides. Full article

(This article belongs to the Special Issue Massive Sulfide Deposits all around the World)

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25 pages, 10478 KiB

Open AccessArticle

Sulfur Isotope Ratios from VMS Deposits in the Penokean Volcanic Belt, Great Lakes Region, USA: Constraints on the Source of Sulfur in a Paleoproterozoic Intra-Arc Rift

by Nicholas Moleski, Anthony Boxleiter and Joyashish Thakurta

Minerals 2019, 9(1), 6; https://doi.org/10.3390/min9010006 - 22 Dec 2018

Cited by 6 | Viewed by 4880

Abstract

The Paleoproterozoic (~1.8 Ga) Penokean Volcanic Belt (PVB) in the Great Lakes Region of North America hosts several polymetallic volcanogenic massive sulfide (VMS) deposits. These deposits were formed by back-arc extensional volcanism during the accretion of island-arc terranes along the southern margin of [...] Read more.

The Paleoproterozoic (~1.8 Ga) Penokean Volcanic Belt (PVB) in the Great Lakes Region of North America hosts several polymetallic volcanogenic massive sulfide (VMS) deposits. These deposits were formed by back-arc extensional volcanism during the accretion of island-arc terranes along the southern margin of the Archean Superior Craton. This study reports δ³⁴S values obtained from sulfide minerals collected from eight VMS deposits in the PVB: Back Forty, Bend, Eisenbrey, Flambeau, Horseshoe, Lynne, Reef, and Schoolhouse. The average δ³⁴S values from most of these deposits lie within the mantle-range between −2 and 2‰, relative to Vienna Canyon Diablo Troilite (V-CDT). Average δ³⁴S values from Back Forty and Lynne deposits are slightly higher, at 2.5 and 2.4‰, respectively. No systematic variation in δ³⁴S was observed based on factors such as the kind of sulfide mineral, ore-texture, type of host rock, or the nature of host-rock alteration. The narrow observed range from the PVB offers a clear indication that sulfur in the mineralizing fluid, originated predominantly from a magmatic source. If there was a significant contribution of sulfur from seawater, the δ³⁴S of seawater sulfur must also have been close to the mantle range. Slightly higher values from Back Forty and Lynne indicate minor involvement of oxidized sulfur at shallow water levels, possibly derived from the continental margin. Full article

(This article belongs to the Special Issue Massive Sulfide Deposits all around the World)

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29 pages, 69075 KiB

Open AccessArticle

Ore Genesis and Geodynamic Setting of Laochang Ag-Pb-Zn-Cu Deposit, Southern Sanjiang Tethys Metallogenic Belt, China: Constraints from Whole Rock Geochemistry, Trace Elements in Sphalerite, Zircon U-Pb Dating and Pb Isotopes

by Chen Wei, Lin Ye, Zhilong Huang, Wei Gao, Yusi Hu, Zhenli Li and Jiawei Zhang

Minerals 2018, 8(11), 516; https://doi.org/10.3390/min8110516 - 8 Nov 2018

Cited by 23 | Viewed by 6953

Abstract

The Laochang Ag-Pb-Zn-Cu deposit, located in the southern margin of the Sanjiang Tethys Metallogenic Belt (STMB), is the typical Ag-Pb-Zn-Cu deposit in this region. Its orebodies are hosted in the Carboniferous Yiliu Formation volcanic-sedimentary cycle and occur as stratiform, stratoid and lenticular. Whether [...] Read more.

The Laochang Ag-Pb-Zn-Cu deposit, located in the southern margin of the Sanjiang Tethys Metallogenic Belt (STMB), is the typical Ag-Pb-Zn-Cu deposit in this region. Its orebodies are hosted in the Carboniferous Yiliu Formation volcanic-sedimentary cycle and occur as stratiform, stratoid and lenticular. Whether or not the stratabound ore belong to the volcanogenic massive sulfide (VMS) deposit remains unclear and controversial. In this paper, the whole rock geochemistry, trace elements in sphalerite, U-Pb zircon chronology and Pb isotopes were investigated, aiming to provide significant insights into the genesis and geodynamic setting of the Laochang deposit. Lead isotope ratios of pyrite and sphalerite from the stratabound ore are 18.341 to 18.915 for ²⁰⁶Pb/²⁰⁴Pb; 15.376 to 15.770 for ²⁰⁷Pb/²⁰⁴Pb; and 38.159 to 39.200 for ²⁰⁸Pb/²⁰⁴Pb—which display a steep linear trend on Pb-Pb diagrams. This indicates a binary mixing of lead components derived from leaching between the host volcanic rock and mantle reservoir. Sphalerite from stratabound ores is relatively enriched in Fe, Mn, In, Sn, and Ga—similar to typical VMS deposits. Moreover, the Carboniferous volcanic rock hosting the stratabound Ag-Pb-Zn-Cu ores has a zircon U-Pb age of 312 ± 4 Ma; together with previous geochronological and geological evidences, thus, we consider that the stratabound mineralization occur in the Late Paleozoic (~323–308 Ma). Collectively, these geologic, geochemical, and isotopic data confirm that the stratabound ores should be assigned to Carboniferous VMS mineralization. In addition, volcanic rocks hosting the stratabound ore exhibit elevated high field strength elements (HFSEs, Nb, Ta, Zr and Hf) abundance, slight enrichment of light rare earth element (LREE), and depletion of Ba and Sr with obvious Nb-Ta anomalies. Such characteristics suggest that their magma is similar to typical oceanic island basalt. In addition, the oceanic island basalt (OIB)-like volcanic rocks were formed at Late Paleozoic, which could be approximately synchronous with the VMS mineralization at Laochang. Thus, it is suggested that the Laochang VMS mineralization was generated in the oceanic island setting prior to the initial subduction of the Changning-Menglian Paleo-Tethys Ocean. Full article

(This article belongs to the Special Issue Massive Sulfide Deposits all around the World)

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24 pages, 7563 KiB

Open AccessFeature PaperArticle

The Discovery of the Romero VMS Deposit and Its Bearing on the Metallogenic Evolution of Hispaniola during the Cretaceous

by Lisard Torró, Joaquín A. Proenza, Julio Espaillat, Albert Joan Belén-Manzeta, María Clara Román-Alday, Alberto Amarante, Norverto González, Jorge Espinoza, Manuel Jesús Román-Alpiste and Carl E. Nelson

Minerals 2018, 8(11), 507; https://doi.org/10.3390/min8110507 - 6 Nov 2018

Cited by 5 | Viewed by 5832

Abstract

The recently discovered Romero deposit, located in the Tres Palmas district, Cordillera Central of the Dominican Republic, has probable reserves of 840,000 oz gold, 980,000 oz silver and 136 Mlb copper. Mineralization is hosted by intermediate volcanic and volcaniclastic rocks of the lower [...] Read more.

The recently discovered Romero deposit, located in the Tres Palmas district, Cordillera Central of the Dominican Republic, has probable reserves of 840,000 oz gold, 980,000 oz silver and 136 Mlb copper. Mineralization is hosted by intermediate volcanic and volcaniclastic rocks of the lower stratigraphic sequence of the Cretaceous Tireo formation. The andesitic host rocks yield a U-Pb zircon concordia age of 116 ± 10 Ma. Au–Ag–Cu(–Zn) mineralization is divided into: (1) an upper domain with stacked massive sulfide lenses and sulfide dissemination within a 20-m-thick level of massive anhydrite-gypsum nodules, and (2) a lower domain with a high-grade stockwork mineralization in the form of cm-scale veins with open space fillings of fibrous silica and chalcopyrite, sphalerite, pyrite (+electrum ± Au–Ag tellurides). The δ³⁴S values of sulfides from the upper (−7.6 and +0.9‰) and lower (−2.4 and +5.6‰) domains are consistent with a heterogeneous sourcing of S, probably combining inorganically and organically induced reduction of Albian-Aptian seawater sulfate. Despite this, a magmatic source for sulfur cannot be discarded. The δ³⁴S (+19.2 and +20.0‰) and δ¹⁸O (+12.5 and +14.2‰) values of anhydrite-gypsum nodules are also consistent with a seawater sulfate source and suggest crystallization in equilibrium with aqueous sulfides at temperatures higher than 250 °C. These data point to a classification of Romero as a volcanogenic massive sulfide (VMS) deposit formed in an axial position of the Greater Antilles paleo-arc in connection with island arc tholeiitic magmatism during a steady-state subduction regime. Circulation of hydrothermal fluids could have been promoted by a local extensional tectonic regime expressed in the Tres Palmas district as a graben structure. Full article

(This article belongs to the Special Issue Massive Sulfide Deposits all around the World)

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25 pages, 11871 KiB

Open AccessArticle

Mineral Assemblages, Textures and In Situ Sulphur Isotope Geochemistry of Sulphide Mineralization from the Cyprus-Type Ice Volcanogenic Massive Sulphide (VMS) Deposit, Yukon, Canada

by Mervin J. McDonald, Stephen J. Piercey, Graham D. Layne, Lee C. Pigage and Glenn Piercey

Minerals 2018, 8(11), 501; https://doi.org/10.3390/min8110501 - 1 Nov 2018

Cited by 8 | Viewed by 6519

Abstract

The Permian (~273–274 Ma) Ice volcanogenic massive sulphide (VMS) deposit represents a mound shaped Cyprus (mafic)-type VMS deposit (~4.5 Mt @ 1.5% Cu) hosted in basaltic rocks of Slide Mountain terrane. The deposit consists of massive sulphides that are underlain by a chlorite-sulphide-hematite-rich [...] Read more.

The Permian (~273–274 Ma) Ice volcanogenic massive sulphide (VMS) deposit represents a mound shaped Cyprus (mafic)-type VMS deposit (~4.5 Mt @ 1.5% Cu) hosted in basaltic rocks of Slide Mountain terrane. The deposit consists of massive sulphides that are underlain by a chlorite-sulphide-hematite-rich stringer pipe, and overlain by a hematite-(pyrite)-rich exhalative chert. The sulphides are divided into five facies: (1) pyrite-rich; (2) pyrite-bornite-rich; (3) pyrite-chalcopyrite-rich; (4) hematite-pyrite; and (5) stringer sulphide. The sulphides have a distinct paragenetic and textural evolution in the massive sulphide that reflect: (1) an early, low temperature stage (<250 °C dominated by Fe-Zn-Cu-rich mineralization; (2) an intermediate, high temperature stage (>300 °C) dominated by Cu-Fe-rich mineralization; and (3) a late, low temperature phase (<150 °C) dominated by Fe-rich mineralization. In situ sulphur isotope data pyrite and chalcopyrite (by secondary ion mass spectrometry (SIMS)) range from δ³⁴S = +1.8‰ to +8.2‰, but vary as a function of paragenesis and temperature of deposition. Both early and late forming sulfides were dominated by sulphur from partial thermochemical sulphate reduction (TSR) of seawater sulfate, whereas intermediate, high temperature mineralization was dominated leached, igneous sulphur from basement rocks. These results are similar to modern seafloor vents and many ancient VMS deposits. Full article

(This article belongs to the Special Issue Massive Sulfide Deposits all around the World)

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