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Ursoš Herlec - One of the best experts on this subject based on the ideXlab platform.

  • Hydrocarbon Biomarkers in the Topla-Mežica Zinc-Lead Deposits, Northern Karavanke/Drau Range, Slovenia: Paleoenvironment at the Site of Ore Formation
    Economic Geology, 2006
    Co-Authors: Jorge E. Spangenberg, Ursoš Herlec
    Abstract:

    The Mississippi Valley-type zinc and Lead Deposits at Topla (250,150 metric tons (t) of ore grading 10 wt % Zn and 3.3 wt % Pb) and Mežica (19 million metric tons (Mt) of ore grading 5.3 wt % Pb and 2.7 wt % Zn) occur within the Middle to Upper Triassic platform carbonate rocks of the northern Karavanke/Drau Range geotectonic units of the Eastern Alps, Slovenia. The ore and host rocks of these Deposits have been investigated by a combination of inorganic and organic geochemical methods to determine major, trace, and rare earth element (REE) concentrations, hydrocarbon distribution, and stable isotope ratios of carbonates, kerogen, extractable organic matter, and individual hydrocarbons. These data combined with sedimentological evidence provide insight into the paleoenvironmental conditions at the site of ore formation. The carbonate isotope composition, the REE patterns, and the distribution of hydrocarbon biomarkers (normal alkanes and steranes) suggest a marine depositional environment. At Topla, a relatively high concentration of redox sensitive trace elements (V, Mo, U) in the host dolostones and REE patterns parallel to that of the North American shale composite suggest that sediments were deposited in a reducing environment. Anoxic conditions enhanced the preservation of organic matter and resulted in relatively higher total organic carbon contents (up to 0.4 wt %). The isotopic composition of the kerogen (δ 13 C kerogen = −29.4 to −25.0‰, δ 15 N kerogen = −13.6 to 6.8‰) suggests that marine algae and/or bacteria were the main source of organic carbon with a very minor contribution from detrital continental plants and a varying degree of alteration. Extractable organic matter from Topla ore is generally depleted in 13 C compared to the associated kerogen, which is consistent with an indigenous source of the bitumens. The mineralization correlates with δ 15 N kerogen values around 0 per mil, 13C depleted kerogen, 13C enriched n -heptadecane, and relatively high concentrations of bacterial hydrocarbon biomarkers, indicating a high cyanobacterial biomass at the site of ore formation. Abundant dissimilatory sulfate-reducing bacteria, feeding on the cyanobacterial remains, led to accumulation of biogenic H 2 S in the pore water of the sediments. This biogenic H 2 S was mainly incorporated into sedimentary organic matter and diagenetic pyrite. Higher bacterial activity at the ore site also is indicated by specific concentration ratios of hydrocarbons, which are roughly correlated with total Pb plus Zn contents. This correlation is consistent with mixing of hydrothermal metal-rich fluids and local bacteriogenic sulfide sulfur. The new geochemical data provide supporting evidence that Topla is a low-temperature Mississippi Valley-type deposit formed in an anoxic supratidal saline to hypersaline environment. A laminated cyanobacterial mat, with abundant sulfate-reducing bacteria was the main site of sulfate reduction.

  • hydrocarbon biomarkers in the topla mežica zinc Lead Deposits northern karavanke drau range slovenia paleoenvironment at the site of ore formation
    Economic Geology, 2006
    Co-Authors: Jorge E. Spangenberg, Ursoš Herlec
    Abstract:

    The Mississippi Valley-type zinc and Lead Deposits at Topla (250,150 metric tons (t) of ore grading 10 wt % Zn and 3.3 wt % Pb) and Mežica (19 million metric tons (Mt) of ore grading 5.3 wt % Pb and 2.7 wt % Zn) occur within the Middle to Upper Triassic platform carbonate rocks of the northern Karavanke/Drau Range geotectonic units of the Eastern Alps, Slovenia. The ore and host rocks of these Deposits have been investigated by a combination of inorganic and organic geochemical methods to determine major, trace, and rare earth element (REE) concentrations, hydrocarbon distribution, and stable isotope ratios of carbonates, kerogen, extractable organic matter, and individual hydrocarbons. These data combined with sedimentological evidence provide insight into the paleoenvironmental conditions at the site of ore formation. The carbonate isotope composition, the REE patterns, and the distribution of hydrocarbon biomarkers (normal alkanes and steranes) suggest a marine depositional environment. At Topla, a relatively high concentration of redox sensitive trace elements (V, Mo, U) in the host dolostones and REE patterns parallel to that of the North American shale composite suggest that sediments were deposited in a reducing environment. Anoxic conditions enhanced the preservation of organic matter and resulted in relatively higher total organic carbon contents (up to 0.4 wt %). The isotopic composition of the kerogen (δ 13 C kerogen = −29.4 to −25.0‰, δ 15 N kerogen = −13.6 to 6.8‰) suggests that marine algae and/or bacteria were the main source of organic carbon with a very minor contribution from detrital continental plants and a varying degree of alteration. Extractable organic matter from Topla ore is generally depleted in 13 C compared to the associated kerogen, which is consistent with an indigenous source of the bitumens. The mineralization correlates with δ 15 N kerogen values around 0 per mil, 13C depleted kerogen, 13C enriched n -heptadecane, and relatively high concentrations of bacterial hydrocarbon biomarkers, indicating a high cyanobacterial biomass at the site of ore formation. Abundant dissimilatory sulfate-reducing bacteria, feeding on the cyanobacterial remains, led to accumulation of biogenic H 2 S in the pore water of the sediments. This biogenic H 2 S was mainly incorporated into sedimentary organic matter and diagenetic pyrite. Higher bacterial activity at the ore site also is indicated by specific concentration ratios of hydrocarbons, which are roughly correlated with total Pb plus Zn contents. This correlation is consistent with mixing of hydrothermal metal-rich fluids and local bacteriogenic sulfide sulfur. The new geochemical data provide supporting evidence that Topla is a low-temperature Mississippi Valley-type deposit formed in an anoxic supratidal saline to hypersaline environment. A laminated cyanobacterial mat, with abundant sulfate-reducing bacteria was the main site of sulfate reduction.

Jorge E. Spangenberg - One of the best experts on this subject based on the ideXlab platform.

  • Hydrocarbon Biomarkers in the Topla-Mežica Zinc-Lead Deposits, Northern Karavanke/Drau Range, Slovenia: Paleoenvironment at the Site of Ore Formation
    Economic Geology, 2006
    Co-Authors: Jorge E. Spangenberg, Ursoš Herlec
    Abstract:

    The Mississippi Valley-type zinc and Lead Deposits at Topla (250,150 metric tons (t) of ore grading 10 wt % Zn and 3.3 wt % Pb) and Mežica (19 million metric tons (Mt) of ore grading 5.3 wt % Pb and 2.7 wt % Zn) occur within the Middle to Upper Triassic platform carbonate rocks of the northern Karavanke/Drau Range geotectonic units of the Eastern Alps, Slovenia. The ore and host rocks of these Deposits have been investigated by a combination of inorganic and organic geochemical methods to determine major, trace, and rare earth element (REE) concentrations, hydrocarbon distribution, and stable isotope ratios of carbonates, kerogen, extractable organic matter, and individual hydrocarbons. These data combined with sedimentological evidence provide insight into the paleoenvironmental conditions at the site of ore formation. The carbonate isotope composition, the REE patterns, and the distribution of hydrocarbon biomarkers (normal alkanes and steranes) suggest a marine depositional environment. At Topla, a relatively high concentration of redox sensitive trace elements (V, Mo, U) in the host dolostones and REE patterns parallel to that of the North American shale composite suggest that sediments were deposited in a reducing environment. Anoxic conditions enhanced the preservation of organic matter and resulted in relatively higher total organic carbon contents (up to 0.4 wt %). The isotopic composition of the kerogen (δ 13 C kerogen = −29.4 to −25.0‰, δ 15 N kerogen = −13.6 to 6.8‰) suggests that marine algae and/or bacteria were the main source of organic carbon with a very minor contribution from detrital continental plants and a varying degree of alteration. Extractable organic matter from Topla ore is generally depleted in 13 C compared to the associated kerogen, which is consistent with an indigenous source of the bitumens. The mineralization correlates with δ 15 N kerogen values around 0 per mil, 13C depleted kerogen, 13C enriched n -heptadecane, and relatively high concentrations of bacterial hydrocarbon biomarkers, indicating a high cyanobacterial biomass at the site of ore formation. Abundant dissimilatory sulfate-reducing bacteria, feeding on the cyanobacterial remains, led to accumulation of biogenic H 2 S in the pore water of the sediments. This biogenic H 2 S was mainly incorporated into sedimentary organic matter and diagenetic pyrite. Higher bacterial activity at the ore site also is indicated by specific concentration ratios of hydrocarbons, which are roughly correlated with total Pb plus Zn contents. This correlation is consistent with mixing of hydrothermal metal-rich fluids and local bacteriogenic sulfide sulfur. The new geochemical data provide supporting evidence that Topla is a low-temperature Mississippi Valley-type deposit formed in an anoxic supratidal saline to hypersaline environment. A laminated cyanobacterial mat, with abundant sulfate-reducing bacteria was the main site of sulfate reduction.

  • hydrocarbon biomarkers in the topla mežica zinc Lead Deposits northern karavanke drau range slovenia paleoenvironment at the site of ore formation
    Economic Geology, 2006
    Co-Authors: Jorge E. Spangenberg, Ursoš Herlec
    Abstract:

    The Mississippi Valley-type zinc and Lead Deposits at Topla (250,150 metric tons (t) of ore grading 10 wt % Zn and 3.3 wt % Pb) and Mežica (19 million metric tons (Mt) of ore grading 5.3 wt % Pb and 2.7 wt % Zn) occur within the Middle to Upper Triassic platform carbonate rocks of the northern Karavanke/Drau Range geotectonic units of the Eastern Alps, Slovenia. The ore and host rocks of these Deposits have been investigated by a combination of inorganic and organic geochemical methods to determine major, trace, and rare earth element (REE) concentrations, hydrocarbon distribution, and stable isotope ratios of carbonates, kerogen, extractable organic matter, and individual hydrocarbons. These data combined with sedimentological evidence provide insight into the paleoenvironmental conditions at the site of ore formation. The carbonate isotope composition, the REE patterns, and the distribution of hydrocarbon biomarkers (normal alkanes and steranes) suggest a marine depositional environment. At Topla, a relatively high concentration of redox sensitive trace elements (V, Mo, U) in the host dolostones and REE patterns parallel to that of the North American shale composite suggest that sediments were deposited in a reducing environment. Anoxic conditions enhanced the preservation of organic matter and resulted in relatively higher total organic carbon contents (up to 0.4 wt %). The isotopic composition of the kerogen (δ 13 C kerogen = −29.4 to −25.0‰, δ 15 N kerogen = −13.6 to 6.8‰) suggests that marine algae and/or bacteria were the main source of organic carbon with a very minor contribution from detrital continental plants and a varying degree of alteration. Extractable organic matter from Topla ore is generally depleted in 13 C compared to the associated kerogen, which is consistent with an indigenous source of the bitumens. The mineralization correlates with δ 15 N kerogen values around 0 per mil, 13C depleted kerogen, 13C enriched n -heptadecane, and relatively high concentrations of bacterial hydrocarbon biomarkers, indicating a high cyanobacterial biomass at the site of ore formation. Abundant dissimilatory sulfate-reducing bacteria, feeding on the cyanobacterial remains, led to accumulation of biogenic H 2 S in the pore water of the sediments. This biogenic H 2 S was mainly incorporated into sedimentary organic matter and diagenetic pyrite. Higher bacterial activity at the ore site also is indicated by specific concentration ratios of hydrocarbons, which are roughly correlated with total Pb plus Zn contents. This correlation is consistent with mixing of hydrothermal metal-rich fluids and local bacteriogenic sulfide sulfur. The new geochemical data provide supporting evidence that Topla is a low-temperature Mississippi Valley-type deposit formed in an anoxic supratidal saline to hypersaline environment. A laminated cyanobacterial mat, with abundant sulfate-reducing bacteria was the main site of sulfate reduction.

  • Carbon and oxygen isotope study of hydrothermal carbonates in the zinc-Lead Deposits of the San Vicente district, central Peru: a quantitative modeling on mixing processes and CO2 degassing
    Chemical Geology, 1996
    Co-Authors: Jorge E. Spangenberg, Lluis Fontboté, Z.d. Sharp, Johannes C. Hunziker
    Abstract:

    Abstract Carbon and oxygen isotope studies of the host and gangue carbonates of Mississippi Valley-type zinc-Lead Deposits in the San Vicente District hosted in the Upper Triassic to Lower Jurassic dolostones of the Pucara basin (central Peru) were used to constrain maiels of the ore formation. A mixing model between an incoming hot saline slightly acidic radiogenic (Pb, Sr) fluid and the native formation water explains the overall isotopic variation (δ 13 C = −11.5 to + 2.5‰ relative to PDB and δ 18 O = + 18.0 to + 24.3‰ relative to SMOW) of the carbonate generations. The dolomites formed during the main ore stage show a narrower range (δ 13 C = −0.1 to + 1.7‰ and δ 18 O = + 18.7 to +23.4‰) which is explained by exchange between the mineralizing fluids and the host carbonates combined with changes in temperature and pressure. This model of fluid-rock interaction explains the pervasive alteration of the host dolomite I and precipitation of sphalerite I. The open-space filling hydrothermal white sparry dolomite and the coexisting sphalerite II formed by prolonged fluid-host dolomite interaction and limited CO 2 degassing. Late void-filling dolomite III (or calcite) and the associated sphalerite III formed as the consequence of CO 2 degassing and concomitant pH increase of a slightly acidic ore fluid. Widespread brecciation is associated to CO 2 outgassing. Consequently, pressure variability plays a major role in the ore precipitation during the late hydrothermal events in San Vicente. The presence of native sulfur associated with extremely carbon-light calcites replacing evaporitic sulfates (e.g., δ 13 C = −11.5‰), altered native organic matter and heavier hydrothermal bitumen (from −27.0 to −23.0‰ δ 13 C) points to thermochemical reduction of sulfate and/or thiosulfate. The δ 13 C- and ° 18 O-values of the altered host dolostone and hydrothermal carbonates, and the carbon isotope composition of the associated organic matter show a strong regional homogeneity. These results coupled with the strong mineralogical and petrographic similarities of the different MVT occurrences perhaps reflects the fact that the mineralizing processes were similar in the whole San Vicente belt, suggesting the existence of a common regional mineralizing hydrothermal system with interconnected plumbing.

David L. Leach - One of the best experts on this subject based on the ideXlab platform.

  • Geology and Geochemistry of the Reocín Zinc-Lead Deposit, Basque-Cantabrian Basin, Northern Spain
    Economic Geology, 2003
    Co-Authors: Francisco Velasco, José Miguel Herrero, Iñaki Yusta, José Antonio Alonso, Ignacio Seebold, David L. Leach
    Abstract:

    The Reocin Zn-Pb deposit, 30 km southwest of Santander, Spain, occurs within Lower Cretaceous dolomitized Urgonian limestones on the southern flank of the Santillana syncline. The Reocin deposit is one of the largest known strata-bound, carbonate-hosted, zinc-Lead Deposits in Europe. The total metal endowment of the deposit, including past production and remaining reserves, is 62 Mt of ore grading 8.7 percent Zn and 1.0 percent Pb. The epigenetic mineralization consists of sphalerite and galena, with lesser marcasite and trace pyrite with dolomite as gangue. Microprobe analyses of different generations of dolomite revealed nonstoichiometric compositions with various amounts of iron (up to 14 mol % of FeCO3). Replacement of host dolomite, open-space filling of fractures, and cementation of breccias derived from dissolution collapse are the principal types of ore occurrence. Detailed cross-section mapping indicates a stratigraphic and structural control on the deposit. A stratiform morphology is present in the western part of the orebody (Capa Sur), whereas mineralization in the eastern part is highly discordant but strata bound (Barrendera). Stratigraphic studies demonstrate that synsedimentary tectonic activity, related to the rifting of the North Atlantic (Bay of Biscay), was responsible for variation in sedimentation, presence of unconformities (including paleokarsts), local platform emergence and dolomitization along the N60 fault trend. In the Reocin area, two stages of dolomitization are recognized. The first stage is a pervasive dolomitization of the limestone country rocks that was controlled by faulting and locally affected the upper part of the Aptian and the complete Albian sequence. The second dolomitization event occurred after erosion and was controlled by karstic cavities. This later dolomitization was accompanied by ore deposition and, locally, filling of dolomite sands and clastic sediments in karstic cavities. The circulation of hydrothermal fluids responsible for sulfide deposition and the infilling of karst cavities were broadly contemporaneous, indicating a post-Albian age. Vitrinite reflectance data are consistent with previously measured fluid inclusion temperatures and indicate temperatures of ore deposition that were less than 100°C. Carbon and oxygen isotopic data from samples of regional limestone, host-rock dolostone and ore-stage dolomite suggest an early hydrothermal alteration of limestone to dolostone. This initial dolomitization was followed by a second period of dolomite formation produced by the mixing of basinal metal-rich fluids with local modified seawater. Both dolomitization events occurred under similar conditions from fluids exhibiting characteristics of basinal brines. The δ 34S values of sulfides are between –1.8 and +8.5 per mil, which is consistent with thermochemical sulfate reduction involving organic matter as the main source of reduced sulfur. Galena Lead isotope compositions are among the most radiogenic values reported for Zn-Pb occurrences in Europe, and they are distinct from values reported for galena from other Basque-Cantabrian Deposits. This suggests that a significant part of the Lead was scavenged from the local underlying Asturian sediments. The stratigraphic and structural setting, timing of epigenetic mineralization, mineralogy, and isotopic geochemistry of sulfide and gangue minerals of the Reocin deposit are consistent with the features of most of Mississippi Valley-type ore Deposits.

  • Tectonic controls of Mississippi Valley-type Lead–zinc mineralization in orogenic forelands
    Mineralium Deposita, 2003
    Co-Authors: Dwight C. Bradley, David L. Leach
    Abstract:

    Most of the world's Mississippi Valley-type (MVT) zinc–Lead Deposits occur in orogenic forelands. We examine tectonic aspects of foreland evolution as part of a broader study of why some forelands are rich in MVT Deposits, whereas others are barren. The type of orogenic foreland (collisional versus Andean-type versus inversion-type) is not a first-order control, because each has MVT Deposits (e.g., Northern Arkansas, Pine Point, and Cevennes, respectively). In some MVT districts (e.g., Tri-State and Central Tennessee), mineralization took place atop an orogenic forebulge, a low-amplitude (a few hundred meters), long-wavelength (100–200 km) swell formed by vertical loading of the foreland plate. In the foreland of the active Banda Arc collision zone, a discontinuous forebulge reveals some of the physiographic and geologic complexities of the forebulge environment, and the importance of sea level in determining whether or not a forebulge will emerge and thus be subject to erosion. In addition to those on extant forebulges, some MVT Deposits occur immediately below unconformities that originated at a forebulge, only to be subsequently carried toward the orogen by the plate-tectonic conveyor (e.g., Daniel's Harbour and East Tennessee). Likewise, some Deposits are located along syn-collisional, flexure-induced normal and strike-slip faults in collisional forelands (e.g., Northern Arkansas, Daniel's Harbour, and Tri-State districts). These findings reveal the importance of lithospheric flexure, and suggest a conceptual tectonic model that accounts for an important subset of MVT Deposits—those in the forelands of collisional orogens. The MVT Deposits occur both in flat-lying and in thrust-faulted strata; in the latter group, mineralization postdated thrusting in some instances (e.g., Picos de Europa) but may have predated thrusting in other cases (e.g., East Tennessee).

Yexiang Tong - One of the best experts on this subject based on the ideXlab platform.

  • Tuning the architectures of Lead Deposits on metal substrates by electrodeposition
    Electrochimica Acta, 2008
    Co-Authors: Chen-zhong Yao, Meng Liu, Peng Zhang, Wenxia Zhao, Peng Liu, Yexiang Tong
    Abstract:

    Different morphologies of Lead (Pb) deposited on different metal substrates have been prepared via electrochemical deposition in aqueous solution. The morphologies of as-deposited Lead were determined by scanning electron microscope (SEM). It is found that the various morphologies of the products are dependent on the electrodeposition conditions, including the deposition current densities, concentration of additives, substrates and deposition time. X-ray diffraction (XRD) and transmission electron microscope (TEM) results reveal that all these Lead Deposits with different morphologies can be assigned to the space group Fm-3m (2 2 5).

Léon Dejonghe - One of the best experts on this subject based on the ideXlab platform.

  • the calamine type zinc Lead Deposits in belgium and west germany a product of mesozoic palaeoweathering processes
    Geologica Belgica, 2005
    Co-Authors: Léon Dejonghe, Maria Boni
    Abstract:

    The word "calamine", designating non-sulphide Zn-ores of supergene origin in carbonate rocks, originates from the Belgian locality "La Calamine" where an ore deposit was exploited from the 14 th century up to 1884. The genesis and age of La Calamine, described in the literature as a palaeokarstic type of deposit, have never been fully understood. Likewise, the age of the deep supergene alteration of Zn-Pb veins exploited in Belgian and German neighbouring mining districts has never been clearly determined. This paper aims at identifying the geological constraints responsible for the genesis of willemite-smithsonite-bearing La Calamine deposit, as well as of the deep- reaching gossans of the surrounding Zn-Pb veins. The kaolinised regolith remnants ranging from Uppermost Jurassic to Lower Cretaceous, which developed on the post-Variscan palaeosurface, could be one of the surface expressions of the weathering responsible for the genesis of non-sulphide Zn-ore Deposits in Belgium and Germany. Locally, Upper Cretaceous sediments, whose deposition interrupted the weathering process, cover the regolith. Neither Cainozoic weathering, that was responsible in Belgium for halloysite accumulations at the bottom of giant cryptokarsts, nor Quaternary landscape modelling, should have played a major role in the formation of the economic "calamine-type" Zn-Deposits.

  • zinc Lead Deposits of belgium
    Ore Geology Reviews, 1998
    Co-Authors: Léon Dejonghe
    Abstract:

    The exploitation of Belgian zinc–Lead Deposits dates back to prehistoric times. Its apogee was between 1850 and 1870 and the last mine was closed in 1946. During the period 1837–1945, during which time production levels were recorded, the tonnage of exploited metals reached about 1 500 000 tons Pb+Zn with a Zn/Pb ratio of 8–9. The mineralogy of the Deposits is generally simple: sphalerite, galena, pyrite or marcasite, and locally Ni- and Co-sulfides. Several ore deposit types may be distinguished, including syndiagenetic-, vein and connected flat-, and paleokarstic types. The syndiagenetic Deposits are made up of numerous disseminated-type Deposits with low grades and small tonnages. They are linked to reef facies of Frasnian (=Upper Devonian) carbonate rocks. The largest exploited vein-type Deposits are hosted in Dinantian (=Lower Carboniferous) carbonate rocks. Lead isotopic studies reveal that the main primary source of the metals is in Middle and Upper Devonian sedimentary rocks. Hydrothermal solutions precipitated their metals at temperatures <180°C (110°C in the Verviers Synclinorium) and pressures of 108 Pa (<2×107 Pa in the Verviers Synclinorium). Salinities of the fluids were often between 10 and 23 equiv. wt.% NaCl. The origin of the vein-type Deposits is related to the migration of underground waters, likely gravity-driven, that leach the metals of the surrounding sedimentary rocks (mainly, those of Devonian age, after Pb isotopic data). The La Calamine paleokarstic deposit was the largest Zn ore body in Belgium. It was continuously exploited from the 14th century up to 1884 and produced more than 600 000 tonnes of zinc metal. It was at La Calamine that the chemist Dony, from Liege, invented the first industrial process to transform the calamines into malleable zinc. This was patented by Napoleon I in 1810. Because Belgium occupies an area of the Variscan foreland between Germany and Ireland, a comparison between Deposits of these countries is performed. Belgian Zn–Pb syn-diagenetic deposit are however of types different from the volcanogenic massive sulfide Deposits of Germany, as well as from the strata-bound lenses of Ireland. Prospecting by private companies during the past 50 years has increased the tonnage of reserves adjacent to known Deposits. Lithogeochemical prospecting, however, has not led to the discovery of new economic ore Deposits. The Chaudfontaine stratiform deposit, situated above a Frasnian biostrome, is the only recent drilling discovery.

  • Zinc-Lead Deposits of Belgium
    Ore Geology Reviews, 1998
    Co-Authors: Léon Dejonghe
    Abstract:

    The exploitation of Belgian zinc–Lead Deposits dates back to prehistoric times. Its apogee was between 1850 and 1870 and the last mine was closed in 1946. During the period 1837–1945, during which time production levels were recorded, the tonnage of exploited metals reached about 1 500 000 tons Pb+Zn with a Zn/Pb ratio of 8–9. The mineralogy of the Deposits is generally simple: sphalerite, galena, pyrite or marcasite, and locally Ni- and Co-sulfides. Several ore deposit types may be distinguished, including syndiagenetic-, vein and connected flat-, and paleokarstic types. The syndiagenetic Deposits are made up of numerous disseminated-type Deposits with low grades and small tonnages. They are linked to reef facies of Frasnian (=Upper Devonian) carbonate rocks. The largest exploited vein-type Deposits are hosted in Dinantian (=Lower Carboniferous) carbonate rocks. Lead isotopic studies reveal that the main primary source of the metals is in Middle and Upper Devonian sedimentary rocks. Hydrothermal solutions precipitated their metals at temperatures