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Ian H Campbell - One of the best experts on this subject based on the ideXlab platform.
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platinum group Element geochemistry of the volcanic rocks associated with the jaguar and bentley cu zn volcanogenic massive sulfide vms deposits western australia implications for the role of Chalcophile Element fertility on vms mineralization
Mineralium Deposita, 2021Co-Authors: Jungwoo Park, Ian H CampbellAbstract:We report whole-rock major, trace, and platinum-group Element (PGE) geochemistry of volcanic rocks from the Teutonic Bore complex that hosts the Jaguar and Bentley Cu–Zn volcanogenic massive sulfide (VMS) deposits. This study aims to understand their sulfide saturation history and Chalcophile Element evolution during differentiation of the Jaguar and Bentley magmas, and investigate the role of Chalcophile Element fertility on the formation of VMS deposits. The fractionated primitive mantle–normalized trace Element patterns, with negative Nb and Ti anomalies of basalts, andesites, dacites, and rhyolites from Jaguar and Bentley, are similar to each other. The trace Elements and PGE show continuous variations when plotted against fractionation indices such as Yb, which can be explained by a two-stage fractional crystallization model: stage 1 Rayleigh fractionation of plagioclase + clinopyroxene + Cr-spinel, and stage 2 the fractional of plagioclase + clinopyroxene + magnetite + 0.1 wt% sulfide liquid. Dolerites, which postdate the mineralization, differ from the other rock types and require a different magma source. Andesite and basalt are the most PGE-enriched lithologies in Jaguar and Bentley. The PGE behave incompatibly in the early stage of magma differentiation at 4 ppm Yb, indicating sulfide saturation at this point. When Pd/MgO and Pd/Pt are used as Chalcophile Element fertility indicators, the andesite before sulfide saturation (< 4 ppm Yb) is as fertile as the magmas associated with porphyry Cu-only deposits. In contrast, the andesite after sulfide saturation and other lithologies are characterized by markedly depleted fertility similar to those of barren suites. This suggests that sulfide-undersaturated andesite, and probably basalt, may have been a significant source for Cu in the Jaguar and Bentley Cu–Zn VMS deposits. However, the Au fertility of the Jaguar and Bentley andesite must have been low and not enough to form Au-rich VMS deposits because their Pd/MgO and Pd/Pt values are 5–10 times lower than those of andesite and dacite from the modern Au-rich seafloor massive sulfide deposits. This can be explained if ore formation occurred shortly after sulfide saturation. If the amount of sulfide melt to precipitate was small, Au, with its high partition coefficient into immiscible sulfide melts, would have been largely stripped from the silicate melt, whereas Cu, with its lower partition coefficient, would be little affected. Our study shows that Chalcophile Element fertility may play an important role in the formation of VMS deposits, especially in controlling the Au contents of the ore, if the magmatic-hydrothermal component is the dominant source for metals in VMS systems.
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Chalcophile Element fertility and the formation of porphyry Cu ± Au deposits
Mineralium Deposita, 2019Co-Authors: Jungwoo Park, Ian H Campbell, Sanjeewa P K Malaviarachchi, Helen A CockerAbstract:Chalcophile Element fertility, the Chalcophile metal abundance in the source magma, is likely to be a critical factor for the formation of porphyry Cu ± Au deposits. In this study, we provide evidence to support this hypothesis by comparing the platinum group Element (PGE) geochemistry of barren and ore-bearing Cu ± Au granitic suites. We report the PGE contents of three barren volcanic and subvolcanic suites from Argentina and Japan and two Cu ± Au bearing suites from Indonesia and Chile. These results are compared with those from previous studies of a porphyry Cu-only subvolcanic suite from Chile and three porphyry Cu-Au-bearing suites from Australia and the USA. The barren suites are depleted in PGE abundances by the time of fluid exsolution (
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Chalcophile Element fertility and the formation of porphyry cu au deposits
Mineralium Deposita, 2019Co-Authors: Jungwoo Park, Ian H Campbell, Sanjeewa P K Malaviarachchi, Helen A Cocker, Hongda Hao, Suzanne Mahlburg KayAbstract:Chalcophile Element fertility, the Chalcophile metal abundance in the source magma, is likely to be a critical factor for the formation of porphyry Cu ± Au deposits. In this study, we provide evidence to support this hypothesis by comparing the platinum group Element (PGE) geochemistry of barren and ore-bearing Cu ± Au granitic suites. We report the PGE contents of three barren volcanic and subvolcanic suites from Argentina and Japan and two Cu ± Au bearing suites from Indonesia and Chile. These results are compared with those from previous studies of a porphyry Cu-only subvolcanic suite from Chile and three porphyry Cu-Au-bearing suites from Australia and the USA. The barren suites are depleted in PGE abundances by the time of fluid exsolution (< 0.1 ppb Pd and Pd/Pt < ~ 3), which is attributed to early sulfide saturation in a mid to lower crustal magma chamber. In contrast, the Cu ± Au ore-bearing suites contain at least an order of magnitude higher PGE contents than the barren ones at fluid saturation (up to ~ 10 ppb Pd and Pd/Pt of 0.1–40). They are characterized by late sulfide saturation, which allows both Chalcophile Elements and sulfur to concentrate by fractional crystallization before volatile saturation. We suggest that plots of Pd/MgO against Pd/Pt for igneous suites can be used to estimate Chalcophile Element fertility and distinguish between barren, porphyry Cu, and porphyry Cu-Au granitoid systems. The positive correlation of these Chalcophile Element fertility indicators and ore grades suggests that metal contents in magmas play an important role in controlling ore grade, particularly Au, in porphyry Cu ± Au deposits.
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Chalcophile Element geochemistry of the Boggy Plain zoned pluton, southeastern Australia: a S-saturated barren compositionally diverse magmatic system
Contributions to Mineralogy and Petrology, 2013Co-Authors: Jungwoo Park, Ian H Campbell, Ryan B. Ickert, Charlotte M. AllenAbstract:The behavior of the platinum group Elements (PGE) and Re in felsic magmas is poorly understood due to scarcity of data. We report the concentrations of Ni, Cu, Re, and PGE in the compositionally diverse Boggy Plain zoned pluton (BPZP), which shows a variation of rock type from gabbro through granodiorite and granite to aplite with a SiO_2 range from 52 to 74 wt %. In addition, major silicate and oxide minerals were analyzed for Ni, Cu, and Re, and a systematic sulfide study was carried out to investigate the role of silicate, oxide, and sulfide minerals on Chalcophile Element geochemistry of the BPZP. Mass balance calculation shows that the whole rock Cu budget hosted by silicate and oxide minerals is 70 wt %) is held in major silicate and oxide minerals. Rhenium is dominantly hosted by magnetite and ilmenite. Ovoid-shaped sulfide blebs occur at the boundary between pyroxene phenocrysts and neighboring interstitial phases or within interstitial minerals in the gabbro and the granodiorite. The blebs are composed of pyrrhotite, pyrite, chalcopyrite, and S-bearing Fe-oxide, which contain total trace metals (Co, Ni, Cu, Ag, Pb) up to ~16 wt %. The mineral assemblage, occurrence, shape, and composition of the sulfide blebs are a typical of magmatic sulfide. PGE concentrations in the BPZP vary by more than two orders of magnitude from gabbro (2.7–7.8 ppb Pd, 0.025–0.116 ppb Ir) to aplite (0.05 ppb Pd, 0.001 ppb Ir). Nickel, Cu, Re, and PGE concentrations are positively correlated with MgO in all the rock types although there is a clear discontinuity between the granodiorite and the granite in the trends for Ni, Rh, and Ir when plotted against MgO. Cu/Pd values gradually increase from 6,100 to 52,600 as the MgO content decreases. The sulfide petrology and Chalcophile Element geochemistry of the BPZP show that sulfide saturation occurred in the late gabbroic stage of magma differentiation. Segregation and distribution of these sulfide blebs controlled Cu and PGE variations within the BPZP rocks although the magma of each rock type may have experienced a different magma evolution history in terms of crustal assimilation and crystal fractionation. The sulfide melt locked in the cumulate rocks must have sequestered a significant portion of the Chalcophile Elements, which restricted the availability of these metals to magmatic-hydrothermal ore fluids. Therefore, we suggest that the roof rocks that overlay the BPZP were not prospective for magmatic-hydrothermal Cu, Au, or Cu–Au deposits.
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relative oxidation states of magmas inferred from ce iv ce iii in zircon application to porphyry copper deposits of northern chile
Contributions to Mineralogy and Petrology, 2002Co-Authors: Julian R Ballard, Michael J Palin, Ian H CampbellAbstract:Major- and trace-Element compositions of zircons and whole rocks from 14 barren and seven ore-bearing calc-alkaline intrusions from the Chuquicamata-El Abra porphyry copper belt of northern Chile have been measured in situ by excimer laser ablation (ELA) ICP-MS. These data permit the Ce(IV)/Ce(III) ratio within zircon to be calculated using a lattice-strain model for mineral-melt partitioning of Ce(IV) and Ce(III). Zircon Ce(IV)/Ce(III) and EuN/EuN* ratios, and by inference magmatic oxidation states, generally increase from older, mafic to younger, felsic units. Within this sequence, porphyry copper mineralization is directly associated only with intrusions with zircon Ce(IV)/Ce(III)>300 and EuN/EuN*>0.4. Such trends can be understood in terms of interdependent relations between oxygen fugacity, sulfur speciation and solubility, and Chalcophile Element partitioning in silicate magmas. Because zircon occurs in most calc-alkaline intrusions and is resistant to subsolidus alteration, zircon Ce(IV)/Ce(III) ratios provide a useful tool for evaluating the economic potential of such rocks for magmatic-hydrothermal Cu±Au mineralization. The approach is general and may provide a means to infer relative oxidation state in a wide range of intermediate to felsic igneous rocks.
Jungwoo Park - One of the best experts on this subject based on the ideXlab platform.
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platinum group Element geochemistry of the volcanic rocks associated with the jaguar and bentley cu zn volcanogenic massive sulfide vms deposits western australia implications for the role of Chalcophile Element fertility on vms mineralization
Mineralium Deposita, 2021Co-Authors: Jungwoo Park, Ian H CampbellAbstract:We report whole-rock major, trace, and platinum-group Element (PGE) geochemistry of volcanic rocks from the Teutonic Bore complex that hosts the Jaguar and Bentley Cu–Zn volcanogenic massive sulfide (VMS) deposits. This study aims to understand their sulfide saturation history and Chalcophile Element evolution during differentiation of the Jaguar and Bentley magmas, and investigate the role of Chalcophile Element fertility on the formation of VMS deposits. The fractionated primitive mantle–normalized trace Element patterns, with negative Nb and Ti anomalies of basalts, andesites, dacites, and rhyolites from Jaguar and Bentley, are similar to each other. The trace Elements and PGE show continuous variations when plotted against fractionation indices such as Yb, which can be explained by a two-stage fractional crystallization model: stage 1 Rayleigh fractionation of plagioclase + clinopyroxene + Cr-spinel, and stage 2 the fractional of plagioclase + clinopyroxene + magnetite + 0.1 wt% sulfide liquid. Dolerites, which postdate the mineralization, differ from the other rock types and require a different magma source. Andesite and basalt are the most PGE-enriched lithologies in Jaguar and Bentley. The PGE behave incompatibly in the early stage of magma differentiation at 4 ppm Yb, indicating sulfide saturation at this point. When Pd/MgO and Pd/Pt are used as Chalcophile Element fertility indicators, the andesite before sulfide saturation (< 4 ppm Yb) is as fertile as the magmas associated with porphyry Cu-only deposits. In contrast, the andesite after sulfide saturation and other lithologies are characterized by markedly depleted fertility similar to those of barren suites. This suggests that sulfide-undersaturated andesite, and probably basalt, may have been a significant source for Cu in the Jaguar and Bentley Cu–Zn VMS deposits. However, the Au fertility of the Jaguar and Bentley andesite must have been low and not enough to form Au-rich VMS deposits because their Pd/MgO and Pd/Pt values are 5–10 times lower than those of andesite and dacite from the modern Au-rich seafloor massive sulfide deposits. This can be explained if ore formation occurred shortly after sulfide saturation. If the amount of sulfide melt to precipitate was small, Au, with its high partition coefficient into immiscible sulfide melts, would have been largely stripped from the silicate melt, whereas Cu, with its lower partition coefficient, would be little affected. Our study shows that Chalcophile Element fertility may play an important role in the formation of VMS deposits, especially in controlling the Au contents of the ore, if the magmatic-hydrothermal component is the dominant source for metals in VMS systems.
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Chalcophile Element fertility and the formation of porphyry Cu ± Au deposits
Mineralium Deposita, 2019Co-Authors: Jungwoo Park, Ian H Campbell, Sanjeewa P K Malaviarachchi, Helen A CockerAbstract:Chalcophile Element fertility, the Chalcophile metal abundance in the source magma, is likely to be a critical factor for the formation of porphyry Cu ± Au deposits. In this study, we provide evidence to support this hypothesis by comparing the platinum group Element (PGE) geochemistry of barren and ore-bearing Cu ± Au granitic suites. We report the PGE contents of three barren volcanic and subvolcanic suites from Argentina and Japan and two Cu ± Au bearing suites from Indonesia and Chile. These results are compared with those from previous studies of a porphyry Cu-only subvolcanic suite from Chile and three porphyry Cu-Au-bearing suites from Australia and the USA. The barren suites are depleted in PGE abundances by the time of fluid exsolution (
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Chalcophile Element fertility and the formation of porphyry cu au deposits
Mineralium Deposita, 2019Co-Authors: Jungwoo Park, Ian H Campbell, Sanjeewa P K Malaviarachchi, Helen A Cocker, Hongda Hao, Suzanne Mahlburg KayAbstract:Chalcophile Element fertility, the Chalcophile metal abundance in the source magma, is likely to be a critical factor for the formation of porphyry Cu ± Au deposits. In this study, we provide evidence to support this hypothesis by comparing the platinum group Element (PGE) geochemistry of barren and ore-bearing Cu ± Au granitic suites. We report the PGE contents of three barren volcanic and subvolcanic suites from Argentina and Japan and two Cu ± Au bearing suites from Indonesia and Chile. These results are compared with those from previous studies of a porphyry Cu-only subvolcanic suite from Chile and three porphyry Cu-Au-bearing suites from Australia and the USA. The barren suites are depleted in PGE abundances by the time of fluid exsolution (< 0.1 ppb Pd and Pd/Pt < ~ 3), which is attributed to early sulfide saturation in a mid to lower crustal magma chamber. In contrast, the Cu ± Au ore-bearing suites contain at least an order of magnitude higher PGE contents than the barren ones at fluid saturation (up to ~ 10 ppb Pd and Pd/Pt of 0.1–40). They are characterized by late sulfide saturation, which allows both Chalcophile Elements and sulfur to concentrate by fractional crystallization before volatile saturation. We suggest that plots of Pd/MgO against Pd/Pt for igneous suites can be used to estimate Chalcophile Element fertility and distinguish between barren, porphyry Cu, and porphyry Cu-Au granitoid systems. The positive correlation of these Chalcophile Element fertility indicators and ore grades suggests that metal contents in magmas play an important role in controlling ore grade, particularly Au, in porphyry Cu ± Au deposits.
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Chalcophile Element geochemistry of the Boggy Plain zoned pluton, southeastern Australia: a S-saturated barren compositionally diverse magmatic system
Contributions to Mineralogy and Petrology, 2013Co-Authors: Jungwoo Park, Ian H Campbell, Ryan B. Ickert, Charlotte M. AllenAbstract:The behavior of the platinum group Elements (PGE) and Re in felsic magmas is poorly understood due to scarcity of data. We report the concentrations of Ni, Cu, Re, and PGE in the compositionally diverse Boggy Plain zoned pluton (BPZP), which shows a variation of rock type from gabbro through granodiorite and granite to aplite with a SiO_2 range from 52 to 74 wt %. In addition, major silicate and oxide minerals were analyzed for Ni, Cu, and Re, and a systematic sulfide study was carried out to investigate the role of silicate, oxide, and sulfide minerals on Chalcophile Element geochemistry of the BPZP. Mass balance calculation shows that the whole rock Cu budget hosted by silicate and oxide minerals is 70 wt %) is held in major silicate and oxide minerals. Rhenium is dominantly hosted by magnetite and ilmenite. Ovoid-shaped sulfide blebs occur at the boundary between pyroxene phenocrysts and neighboring interstitial phases or within interstitial minerals in the gabbro and the granodiorite. The blebs are composed of pyrrhotite, pyrite, chalcopyrite, and S-bearing Fe-oxide, which contain total trace metals (Co, Ni, Cu, Ag, Pb) up to ~16 wt %. The mineral assemblage, occurrence, shape, and composition of the sulfide blebs are a typical of magmatic sulfide. PGE concentrations in the BPZP vary by more than two orders of magnitude from gabbro (2.7–7.8 ppb Pd, 0.025–0.116 ppb Ir) to aplite (0.05 ppb Pd, 0.001 ppb Ir). Nickel, Cu, Re, and PGE concentrations are positively correlated with MgO in all the rock types although there is a clear discontinuity between the granodiorite and the granite in the trends for Ni, Rh, and Ir when plotted against MgO. Cu/Pd values gradually increase from 6,100 to 52,600 as the MgO content decreases. The sulfide petrology and Chalcophile Element geochemistry of the BPZP show that sulfide saturation occurred in the late gabbroic stage of magma differentiation. Segregation and distribution of these sulfide blebs controlled Cu and PGE variations within the BPZP rocks although the magma of each rock type may have experienced a different magma evolution history in terms of crustal assimilation and crystal fractionation. The sulfide melt locked in the cumulate rocks must have sequestered a significant portion of the Chalcophile Elements, which restricted the availability of these metals to magmatic-hydrothermal ore fluids. Therefore, we suggest that the roof rocks that overlay the BPZP were not prospective for magmatic-hydrothermal Cu, Au, or Cu–Au deposits.
Christina Yan Wang - One of the best experts on this subject based on the ideXlab platform.
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geochemistry of the abulangdang intrusion cumulates of high ti picritic magmas in the emeishan large igneous province sw china
Chemical Geology, 2014Co-Authors: Christina Yan Wang, Sheng-hong Yang, Liang QiAbstract:Abstract The ~ 260 Ma Abulangdang ultramafic intrusion in the Panxi region, SW China, is part of the Emeishan large igneous province (ELIP). The intrusion is composed of dunite and lherzolite with minor olivine gabbro. Olivine crystals in the dunite have Fo values from 89.0 to 86.5 mol%. Chromite grains in both the dunite and lherzolite contain more than 0.5 wt.% TiO2 and show a trend of increasing Fe3 + with increasing Fe2 +/(Mg + Fe2 +). Rocks of the intrusion have γOs(t) values from + 0.1 to + 1.2 and eNd(t) values from − 1.9 to + 2.9, similar to the high-Ti picrites, high-Ti flood basalts and Fe–Ti oxide-bearing, gabbroic intrusions of the ELIP. Modeling indicates that the Abulangdang intrusion formed by accumulation of olivine and chromite from a high-Ti picritic magma, whereas the high-Ti flood basalts and Fe–Ti oxide-bearing, gabbroic intrusions formed from derivative, evolved magmas after the early fractionation of minerals from the high-Ti picritic magma. Both the dunite and lherzolite have relatively high PGE concentrations and primitive mantle-normalized Chalcophile Element patterns with positive Os and Ru anomalies, in contrast to PGE-poor high-Ti flood basalts with negative Os and Ru anomalies. This is consistent with the retention of Ru–Os–Ir trace phases with olivine and chromite in the formation of the Abulangdang intrusion. Using a clinopyroxene geobarometer, the crystallization pressure of the Abulangdang intrusion is calculated to be 7.1 to 8.3 kbar, equivalent to a depth of ~ 21 to 24 km, which is deeper than that estimated for the Fe–Ti oxide-bearing, gabbroic layered intrusions of the ELIP (~ 5 kbar). We propose that large volumes of mantle plume-derived high-Ti picritic magma underplating along the Moho boundary underwent early fractionation before eruption, and some high-Ti picritic magma ascended through a fossil conduit where the Abulangdang intrusion formed. Residual, evolved magmas either from the conduits or underplating magma chamber formed Fe–Ti oxide-bearing, gabbroic layered intrusions or high-Ti flood basalts. In this fashion, the Abulangdang intrusion resembles ultramafic portions that are missing in the Fe–Ti oxide-bearing, gabbroic intrusions of the ELIP.
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Chalcophile Element constraints on magma differentiation of quaternary volcanoes in tengchong sw china
Journal of Asian Earth Sciences, 2013Co-Authors: Xiaowen Huang, Christina Yan Wang, Paul T Robinson, Junhong ZhaoAbstract:Abstract The Tengchong volcanic field comprises numerous Quaternary volcanoes in SW China. The volcanic rocks are grouped into Units 1–4 from the oldest to youngest. Units 1, 3 and 4 are composed of trachybasalt, basaltic trachyandesite and trachyandesite, respectively, and Unit 2 consists of hornblende-bearing dacite. This rock assemblage resembles those of arc volcanic sequences related to oceanic slab subduction. Rocks of Units 1 and 3 contain olivine phenocrysts with Fo contents ranging from 65 to 85 mole%, indicating early fractionation of olivine and chromite prior to the eruption of magma. All the rocks from Units 1, 3 and 4 have very low PGE concentrations, with
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Chalcophile Element geochemistry and petrogenesis of high ti and low ti magmas in the permian emeishan large igneous province sw china
Contributions to Mineralogy and Petrology, 2011Co-Authors: Christina Yan Wang, Mei-fu ZhouAbstract:Sulfide-poor mafic layered intrusions, sills/dykes and lava flows in the Funing region, SW China, are part of the ~260 Ma Emeishan large igneous province. They belong to either a high-Ti group (TiO2 = 1.6–4.4 wt%) with elevated Ti/Y ratios (351–1,018), or a low-Ti group (TiO2 1, low (Y/Pd)PM ratios (0.2–7.1) and nearly constant (Cu/Pd)PM ratios (1.5–3.8). The even and parallel Chalcophile Element patterns of the high-PGE low-Ti subgroup rocks are likely a result of olivine-dominated fractionation under S-undersaturated condition. The low-PGE low-Ti group rocks have low MgO (4.5–8.9 wt%) and very poor PGE (Pt + Pd 0.5–1.6 ppb, Ir 0.004–0.02 ppb) with low Cu/Zr ratios (0.1–0.5), high (Y/Pd)PM (26–70) and variable (Cu/Pd)PM ratios (2.8–14). The trough-like Chalcophile Element patterns of the low-PGE low-Ti subgroup rocks indicate that the magmas were sulfide saturation and sulfide melts were extracted from the magmas. The extracted sulfide melts might be potential Ni–Cu sulfide ores at depth in the Funing region.
Charley J Duran - One of the best experts on this subject based on the ideXlab platform.
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an overview of Chalcophile Element contents of pyrrhotite pentlandite chalcopyrite and pyrite from magmatic ni cu pge deposits
GSA 2020 Connects Online, 2020Co-Authors: Eduardo T Mansur, Sarahjane Barnes, Charley J DuranAbstract:We have compiled the trace Element concentrations in pyrrhotite, pentlandite, chalcopyrite, and pyrite from magmatic Ni-Cu-PGE ore deposits with the aim of understanding their petrogenesis and whether these minerals can be used as indicator minerals. Among the samples, there are some of the most studied world-class Ni-Cu- (Aguablanca, Duluth, Jinchuan, Noril’sk-Talnakh-Kharaelakh, Sudbury, Voisey’s Bay, and others) and PGE-dominated (Bushveld, Lac des Iles, Stillwater, Great Dyke, and Penikat) deposits. Crustal assimilation may be constrained using As/Se and Sb/Se ratios in pentlandite. The degree of interaction between the silicate and sulfide liquids (R-factor) can be estimated by the content of highly Chalcophile Elements (Dsulf liq/sil liq above 1000) in sulfide minerals. The fractional crystallization of the sulfide liquid can be traced using Se/Te ratios of pentlandite. Pyrite formed by exsolution from MSS has higher Rh, Ru, Ir, and Os than co-existing pyrrhotite, whereas pyrite formed by hydrothermal alteration of pyrrhotite inherits the Rh, Ru, Ir, and Os contents of the pyrrhotite it replaced. Sulfide minerals are preserved in transported glacial cover and their trace Element chemistry can be used to discriminate their source. Pentlandite from Ni-Cu deposits has much lower Rh and Pd concentrations than those from PGE-dominated deposits, pyrite from magmatic deposits has higher Co/Sb and Se/As ratios relative to pyrite from hydrothermal deposits, and chalcopyrite from magmatic deposits has much higher Ni and lower Cd concentrations than those from hydrothermal deposits.
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An overview of Chalcophile Element contents of pyrrhotite, pentlandite, chalcopyrite, and pyrite from magmatic Ni-Cu-PGE sulfide deposits
Mineralium Deposita, 2020Co-Authors: Eduardo T Mansur, Sarahjane Barnes, Charley J DuranAbstract:We have compiled the trace Element concentrations in pyrrhotite, pentlandite, chalcopyrite, and pyrite from magmatic Ni-Cu-PGE ore deposits with the aim of understanding their petrogenesis and whether these minerals can be used as indicator minerals. Among the samples, there are some of the most studied world-class Ni-Cu- (Aguablanca, Duluth, Jinchuan, Noril’sk-Talnakh-Kharaelakh, Sudbury, Voisey’s Bay, and others) and PGE-dominated (Bushveld, Lac des Iles, Stillwater, Great Dyke, and Penikat) deposits. Crustal assimilation may be constrained using As/Se and Sb/Se ratios in pentlandite. The degree of interaction between the silicate and sulfide liquids (R-factor) can be estimated by the content of highly Chalcophile Elements (D^sulf liq/sil liq above 1000) in sulfide minerals. The fractional crystallization of the sulfide liquid can be traced using Se/Te ratios of pentlandite. Pyrite formed by exsolution from MSS has higher Rh, Ru, Ir, and Os than co-existing pyrrhotite, whereas pyrite formed by hydrothermal alteration of pyrrhotite inherits the Rh, Ru, Ir, and Os contents of the pyrrhotite it replaced. Sulfide minerals are preserved in transported glacial cover and their trace Element chemistry can be used to discriminate their source. Pentlandite from Ni-Cu deposits has much lower Rh and Pd concentrations than those from PGE-dominated deposits, pyrite from magmatic deposits has higher Co/Sb and Se/As ratios relative to pyrite from hydrothermal deposits, and chalcopyrite from magmatic deposits has much higher Ni and lower Cd concentrations than those from hydrothermal deposits.
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textural and compositional evidence for the formation of pentlandite via peritectic reaction implications for the distribution of highly siderophile Elements
Geology, 2019Co-Authors: Eduardo T Mansur, Sarahjane Barnes, Charley J DuranAbstract:The distribution of highly siderophile Elements is used in the study of a wide variety of geological topics, from planet formation and evolution to the formation of ore deposits. Under mantle and crustal conditions, these Elements behave as highly Chalcophile Elements, and pentlandite (Pn) is an important host for most of these Elements. Therefore, understanding how Pn forms is important to understanding the processes that control these Elements. The classic model for the formation of Pn is that below 650 °C, the high-temperature sulfides—monosulfide solid solution (MSS) and intermediate solid solution (ISS)—are no longer stable and exsolve into pyrrhotite (Po), Pn, and chalcopyrite (Ccp). However, Pn has been shown to be the main host of Pd in many ore deposits, and given that Pd is incompatible with both MSS and ISS, this observation is inconsistent with the exsolution model. Furthermore, experimental work has shown that Pn can form by peritectic reaction between MSS and fractionated sulfide liquid. To date, this type of Pn has not been reported in natural samples. In our study of Chalcophile-Element concentrations in Pn from iconic magmatic Ni–Cu–platinum-group Element deposits, we observed three textures of Pn: contact Pn in between Po and Ccp, granular Pn included within Ccp or Po, and flame Pn included within Po. The contact Pn shows zonation in Mo, Rh, Ru, Re, Os, and Ir, with these Elements being enriched toward the Po contact and depleted toward the Ccp contact. In some cases, Pd displays a zonation antithetical to that of these Elements. In this contribution, we propose that the contact Pn formed via the peritectic reaction described above, and inherited Mo, Ru, Rh, Re, Os, and Ir from the MSS, whereas Pd was contributed from the fractionated sulfide liquid. We expect that this type of Pn should be present wherever MSS and fractionated sulfide liquid remained in contact.
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Chalcophile and platinum group Element distribution in pyrites from the sulfide rich pods of the lac des iles pd deposits western ontario canada implications for post cumulus re equilibration of the ore and the use of pyrite compositions in explorati
Journal of Geochemical Exploration, 2015Co-Authors: Charley J Duran, Sarahjane Barnes, John T CorkeryAbstract:The Lac des Iles Pd-deposits are atypical within the scope of platinum-group Element (PGE) deposits. This is because the deposits do not resemble a classical PGE deposit in a number of ways: the intrusion is small and concentrically zoned; most of the host rocks to the deposits no longer have a primary mineralogy and equilibrated under greenschist conditions; the textures of the rocks from the ore zones are extremely variable; and the ores have very high Pd/Ir and Pd/Pt ratios. In addition to the disseminated sulfides, there are sulfide-rich pods present throughout the stratigraphy. The sulfide mineral textures and proportions within the pods vary from those which are essentially magmatic to those which consist predominantly of pyrite. The pyrite could have been deposited from hydrothermal fluids or it could have formed by alteration of magmatic sulfides. In order to distinguish between these two origins, the PGE and Chalcophile Element contents of the pyrite were investigated. It was found that the pyrite contains Os, Ir, Ru and Rh. These Elements also concentrate in the magmatic sulfides pyrrhotite and pentlandite. Their presence in the pyrite could be explained by redistribution of Fe from pyrrhotite to silicate minerals that are present within and around the sulfide pods, possibly during cooling. Maps of the distribution of the Elements show that there is zoning of the Elements. The IPGE–Rh are present towards the cores of pyrite along with As whereas Co and Se are present towards the rims. Mobile Elements such as Pb, Bi and Ag are present in thin overgrowths at the edges of pyrite and in a few cases, Pt, Te and Sn are also present in the overgrowths. Comparison of the composition and Element distribution with pyrites from other igneous settings (Sudbury and Aguablanca) shows similarities, suggesting a common ore-modifying process. In contrast, pyrites from low-temperature hydrothermal deposits have different compositions. A plot of Co/Se vs Sb/As appears to be effective at separating the igneous pyrites from pyrites found in other settings and could possibly be used in exploration.
Sarahjane Barnes - One of the best experts on this subject based on the ideXlab platform.
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an overview of Chalcophile Element contents of pyrrhotite pentlandite chalcopyrite and pyrite from magmatic ni cu pge deposits
GSA 2020 Connects Online, 2020Co-Authors: Eduardo T Mansur, Sarahjane Barnes, Charley J DuranAbstract:We have compiled the trace Element concentrations in pyrrhotite, pentlandite, chalcopyrite, and pyrite from magmatic Ni-Cu-PGE ore deposits with the aim of understanding their petrogenesis and whether these minerals can be used as indicator minerals. Among the samples, there are some of the most studied world-class Ni-Cu- (Aguablanca, Duluth, Jinchuan, Noril’sk-Talnakh-Kharaelakh, Sudbury, Voisey’s Bay, and others) and PGE-dominated (Bushveld, Lac des Iles, Stillwater, Great Dyke, and Penikat) deposits. Crustal assimilation may be constrained using As/Se and Sb/Se ratios in pentlandite. The degree of interaction between the silicate and sulfide liquids (R-factor) can be estimated by the content of highly Chalcophile Elements (Dsulf liq/sil liq above 1000) in sulfide minerals. The fractional crystallization of the sulfide liquid can be traced using Se/Te ratios of pentlandite. Pyrite formed by exsolution from MSS has higher Rh, Ru, Ir, and Os than co-existing pyrrhotite, whereas pyrite formed by hydrothermal alteration of pyrrhotite inherits the Rh, Ru, Ir, and Os contents of the pyrrhotite it replaced. Sulfide minerals are preserved in transported glacial cover and their trace Element chemistry can be used to discriminate their source. Pentlandite from Ni-Cu deposits has much lower Rh and Pd concentrations than those from PGE-dominated deposits, pyrite from magmatic deposits has higher Co/Sb and Se/As ratios relative to pyrite from hydrothermal deposits, and chalcopyrite from magmatic deposits has much higher Ni and lower Cd concentrations than those from hydrothermal deposits.
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An overview of Chalcophile Element contents of pyrrhotite, pentlandite, chalcopyrite, and pyrite from magmatic Ni-Cu-PGE sulfide deposits
Mineralium Deposita, 2020Co-Authors: Eduardo T Mansur, Sarahjane Barnes, Charley J DuranAbstract:We have compiled the trace Element concentrations in pyrrhotite, pentlandite, chalcopyrite, and pyrite from magmatic Ni-Cu-PGE ore deposits with the aim of understanding their petrogenesis and whether these minerals can be used as indicator minerals. Among the samples, there are some of the most studied world-class Ni-Cu- (Aguablanca, Duluth, Jinchuan, Noril’sk-Talnakh-Kharaelakh, Sudbury, Voisey’s Bay, and others) and PGE-dominated (Bushveld, Lac des Iles, Stillwater, Great Dyke, and Penikat) deposits. Crustal assimilation may be constrained using As/Se and Sb/Se ratios in pentlandite. The degree of interaction between the silicate and sulfide liquids (R-factor) can be estimated by the content of highly Chalcophile Elements (D^sulf liq/sil liq above 1000) in sulfide minerals. The fractional crystallization of the sulfide liquid can be traced using Se/Te ratios of pentlandite. Pyrite formed by exsolution from MSS has higher Rh, Ru, Ir, and Os than co-existing pyrrhotite, whereas pyrite formed by hydrothermal alteration of pyrrhotite inherits the Rh, Ru, Ir, and Os contents of the pyrrhotite it replaced. Sulfide minerals are preserved in transported glacial cover and their trace Element chemistry can be used to discriminate their source. Pentlandite from Ni-Cu deposits has much lower Rh and Pd concentrations than those from PGE-dominated deposits, pyrite from magmatic deposits has higher Co/Sb and Se/As ratios relative to pyrite from hydrothermal deposits, and chalcopyrite from magmatic deposits has much higher Ni and lower Cd concentrations than those from hydrothermal deposits.
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textural and compositional evidence for the formation of pentlandite via peritectic reaction implications for the distribution of highly siderophile Elements
Geology, 2019Co-Authors: Eduardo T Mansur, Sarahjane Barnes, Charley J DuranAbstract:The distribution of highly siderophile Elements is used in the study of a wide variety of geological topics, from planet formation and evolution to the formation of ore deposits. Under mantle and crustal conditions, these Elements behave as highly Chalcophile Elements, and pentlandite (Pn) is an important host for most of these Elements. Therefore, understanding how Pn forms is important to understanding the processes that control these Elements. The classic model for the formation of Pn is that below 650 °C, the high-temperature sulfides—monosulfide solid solution (MSS) and intermediate solid solution (ISS)—are no longer stable and exsolve into pyrrhotite (Po), Pn, and chalcopyrite (Ccp). However, Pn has been shown to be the main host of Pd in many ore deposits, and given that Pd is incompatible with both MSS and ISS, this observation is inconsistent with the exsolution model. Furthermore, experimental work has shown that Pn can form by peritectic reaction between MSS and fractionated sulfide liquid. To date, this type of Pn has not been reported in natural samples. In our study of Chalcophile-Element concentrations in Pn from iconic magmatic Ni–Cu–platinum-group Element deposits, we observed three textures of Pn: contact Pn in between Po and Ccp, granular Pn included within Ccp or Po, and flame Pn included within Po. The contact Pn shows zonation in Mo, Rh, Ru, Re, Os, and Ir, with these Elements being enriched toward the Po contact and depleted toward the Ccp contact. In some cases, Pd displays a zonation antithetical to that of these Elements. In this contribution, we propose that the contact Pn formed via the peritectic reaction described above, and inherited Mo, Ru, Rh, Re, Os, and Ir from the MSS, whereas Pd was contributed from the fractionated sulfide liquid. We expect that this type of Pn should be present wherever MSS and fractionated sulfide liquid remained in contact.
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Chalcophile and platinum group Element distribution in pyrites from the sulfide rich pods of the lac des iles pd deposits western ontario canada implications for post cumulus re equilibration of the ore and the use of pyrite compositions in explorati
Journal of Geochemical Exploration, 2015Co-Authors: Charley J Duran, Sarahjane Barnes, John T CorkeryAbstract:The Lac des Iles Pd-deposits are atypical within the scope of platinum-group Element (PGE) deposits. This is because the deposits do not resemble a classical PGE deposit in a number of ways: the intrusion is small and concentrically zoned; most of the host rocks to the deposits no longer have a primary mineralogy and equilibrated under greenschist conditions; the textures of the rocks from the ore zones are extremely variable; and the ores have very high Pd/Ir and Pd/Pt ratios. In addition to the disseminated sulfides, there are sulfide-rich pods present throughout the stratigraphy. The sulfide mineral textures and proportions within the pods vary from those which are essentially magmatic to those which consist predominantly of pyrite. The pyrite could have been deposited from hydrothermal fluids or it could have formed by alteration of magmatic sulfides. In order to distinguish between these two origins, the PGE and Chalcophile Element contents of the pyrite were investigated. It was found that the pyrite contains Os, Ir, Ru and Rh. These Elements also concentrate in the magmatic sulfides pyrrhotite and pentlandite. Their presence in the pyrite could be explained by redistribution of Fe from pyrrhotite to silicate minerals that are present within and around the sulfide pods, possibly during cooling. Maps of the distribution of the Elements show that there is zoning of the Elements. The IPGE–Rh are present towards the cores of pyrite along with As whereas Co and Se are present towards the rims. Mobile Elements such as Pb, Bi and Ag are present in thin overgrowths at the edges of pyrite and in a few cases, Pt, Te and Sn are also present in the overgrowths. Comparison of the composition and Element distribution with pyrites from other igneous settings (Sudbury and Aguablanca) shows similarities, suggesting a common ore-modifying process. In contrast, pyrites from low-temperature hydrothermal deposits have different compositions. A plot of Co/Se vs Sb/As appears to be effective at separating the igneous pyrites from pyrites found in other settings and could possibly be used in exploration.
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distribution of platinum group and Chalcophile Elements in the aguablanca ni cu sulfide deposit sw spain evidence from a la icp ms study
Chemical Geology, 2012Co-Authors: Ruben Pina, Sarahjane Barnes, Fernando Gervilla, Lorena Ortega, Rosario LunarAbstract:The concentrations of platinum-group Elements (PGE) and Chalcophile Elements Ni, Co, Au, Ag, Se, Re, Cd, Bi, Te and As have been determined by laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) in base metal sulfide minerals (BMS) from the Aguablanca Ni–Cu deposit, SW Spain. The main aim was to constrain the role played by the BMS as hosts of PGE as this reveals important information regarding the processes controlling the distribution of these Elements in the deposit. The BMS (pyrrhotite, pentlandite, chalcopyrite and minor pyrite) occur as semi-massive, disseminated and minor chalcopyrite-veined ores. On the basis of whole rock metal abundances and BMS mineralogy, these ore types have been interpreted to be the result of the fractionation and crystallization of an immiscible sulfide liquid. Platinum-group and Chalcophile Element concentrations vary as a function of the BMS and ore types. The partitioning behavior of some of these metals during the fractional crystallization of the sulfide liquid largely governed their distribution in the ore. Rhenium, Os, Ir, Ru, and Rh occur mostly in solid solution in pyrrhotite and pentlandite from the semi-massive ore which has been interpreted to represent monosulfide solid solution (mss) cumulates. The mss crystallization gave rise to minor Cu-rich sulfide liquid in the form of chalcopyrite veinlets with relatively Pd-, Au- and Ag-enriched chalcopyrite, and minor Re-, IPGE- and Rh-depleted pyrrhotite and pentlandite. Platinum-group Element contents in the BMS from the disseminated ore, interpreted to represent an original unfractionated sulfide melt, are approximately intermediate to the semi-massive and chalcopyrite-veined ores. Palladium and Pt occur mostly associated with Bi, Te, and As forming platinum-group minerals (PGM, Pd–Pt bismuthotellurides and Pt arsenides) within individual BMS grains. This preferential location along with the textures adopted (usually rounded grains and laths) and the temperatures of crystallization (inferred below 500 °C) suggests that Pd and Pt, initially dissolved in the BMS, were exsolved along with Bi, Te and As to form the PGM assemblage present in the ore. Some Pd (approximately 30% of the bulk) remains in solid solution in pentlandite for the three ore types. The presence of Pd in pentlandite is likely a combined effect of limited sulfide fractionation with some of Pd remaining in mss and Pd diffusion into pentlandite from the mss and Cu-rich portions on cooling. Two textural types of pyrite hosting distinct PGE concentrations have been described: (1) large idiomorphic pyrite and (2) ribbon-like pyrite. Idiomorphic pyrite is the unique BMS hosting Pt (with contents as high as 15 ppm) and also contains relatively high Rh concentrations (4–31 ppm). By contrast, ribbon-like pyrite has no Pt and hosts similar Os, Ir, Ru and Rh concentrations (30–360 ppb) to those of the host pyrrhotite to that it replaces. The origin of the idiomorphic grains, whether exsolution products from mss or alteration products of pyrrhotite, is not well known and further work will be necessary to constrain this point. Nevertheless, the presence of PGE hosted by pyrite reveals that this sulfide should not be overlooked as a potential carrier of PGE in Ni–Cu–(PGE) ore deposits.