Microchemical and sulfur isotope constraints on the magmatic and hydrothermal evolution of the Black Swan Succession, Western Australia

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Abstract

The Black Swan Succession consists of an Archean bimodal dacite-komatiite association largely dominated by ultramafic cumulates hosting a number of massive and disseminated magmatic sulfide orebodies. Although it was affected by multiple alteration events, the low degree of penetrative deformation allowed the preservation of magmatic textures and stratigraphic relationships. In this context, we apply a combined multiple sulfur isotope and microchemical approach to unravel the potential of sulfides to simultaneously retain information about their magmatic and hydrothermal history. Negative Δ33S signatures in both massive (− 0.56‰) and disseminated (− 0.66‰) sulfide orebodies reflect the assimilation of photochemically derived sulfur into the komatiite magma, which attained sulfide liquid supersaturation through the assimilation of crustal material analogous to the intercalated breccia dacite hosting colloform sulfides (Δ33S = − 0.91‰). The slightly different Δ33S signatures between disseminated and massive orebodies reflect the assimilation of different proportions of crustally derived sulfur, and imply that the respective sulfide liquids segregated from distinct komatiite magma pulses. Subsequent alteration episodes imparted to the Black Swan Succession a concentric zonation consisting of a serpentinite core and talc-carbonate margins. The Black Swan disseminated orebody extends through both alteration styles without major variations in the dominant millerite-pyrite sulfide assemblage. Pyrite in both serpentinite and talc-carbonate samples exhibits a consistent trace element signature suggesting a relative immobile behavior of Ni and Co during the percolation of the talc-carbonate fluids. Conversely, variable δ34S signatures between the two alteration styles reflect mobilization of sulfur during talc-carbonate alteration. Whereas the 2‰ range of δ34S values in serpentinites can be attributed to moderate equilibrium fractionation processes, the 10‰ range of δ34S values in talc-carbonate rocks suggests that highly oxidizing fluids promoted the mobilization of sulfur as SO42−, which decreased the δ34S of the disseminated sulfides. Furthermore, sulfur isotope and microchemical signatures of euhedral pyrite from intercalated dacitic breccia indicate that this pyrite generation was deposited from a late hydrothermal event, which is characterized by variable and least negative Δ33S signatures (between − 0.20‰ and − 0.48‰) relative to all sulfide orebodies. These features suggest that the late fluids developed in a heterogeneous hydrothermal system with a minor component of sulfur recycled from the sulfide orebodies.

Original languageEnglish
Number of pages19
JournalMineralium Deposita
DOIs
Publication statusE-pub ahead of print - 30 May 2019

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Sulfur Isotopes
sulfur isotopes
sulfur isotope
Sulfides
sulfides
sulfide
Talc
talc
Carbonates
Sulfur
signatures
pyrites
carbonates
sulfur
komatiite
pyrite
assimilation
carbonate
breccia
serpentinite

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@article{cac0b06b63394c72aa758ff20e30ca93,
title = "Microchemical and sulfur isotope constraints on the magmatic and hydrothermal evolution of the Black Swan Succession, Western Australia",
abstract = "The Black Swan Succession consists of an Archean bimodal dacite-komatiite association largely dominated by ultramafic cumulates hosting a number of massive and disseminated magmatic sulfide orebodies. Although it was affected by multiple alteration events, the low degree of penetrative deformation allowed the preservation of magmatic textures and stratigraphic relationships. In this context, we apply a combined multiple sulfur isotope and microchemical approach to unravel the potential of sulfides to simultaneously retain information about their magmatic and hydrothermal history. Negative Δ33S signatures in both massive (− 0.56‰) and disseminated (− 0.66‰) sulfide orebodies reflect the assimilation of photochemically derived sulfur into the komatiite magma, which attained sulfide liquid supersaturation through the assimilation of crustal material analogous to the intercalated breccia dacite hosting colloform sulfides (Δ33S = − 0.91‰). The slightly different Δ33S signatures between disseminated and massive orebodies reflect the assimilation of different proportions of crustally derived sulfur, and imply that the respective sulfide liquids segregated from distinct komatiite magma pulses. Subsequent alteration episodes imparted to the Black Swan Succession a concentric zonation consisting of a serpentinite core and talc-carbonate margins. The Black Swan disseminated orebody extends through both alteration styles without major variations in the dominant millerite-pyrite sulfide assemblage. Pyrite in both serpentinite and talc-carbonate samples exhibits a consistent trace element signature suggesting a relative immobile behavior of Ni and Co during the percolation of the talc-carbonate fluids. Conversely, variable δ34S signatures between the two alteration styles reflect mobilization of sulfur during talc-carbonate alteration. Whereas the 2‰ range of δ34S values in serpentinites can be attributed to moderate equilibrium fractionation processes, the 10‰ range of δ34S values in talc-carbonate rocks suggests that highly oxidizing fluids promoted the mobilization of sulfur as SO42−, which decreased the δ34S of the disseminated sulfides. Furthermore, sulfur isotope and microchemical signatures of euhedral pyrite from intercalated dacitic breccia indicate that this pyrite generation was deposited from a late hydrothermal event, which is characterized by variable and least negative Δ33S signatures (between − 0.20‰ and − 0.48‰) relative to all sulfide orebodies. These features suggest that the late fluids developed in a heterogeneous hydrothermal system with a minor component of sulfur recycled from the sulfide orebodies.",
keywords = "Alteration, Archean, Assimilation, Black Swan, Komatiite, Magmatic nickel deposit, Sulfides, Sulfur isotopes",
author = "Stefano Caruso and Fiorentini, {Marco L.} and Barnes, {Stephen J.} and LaFlamme, {Crystal K.} and Martin, {Laure A.J.}",
year = "2019",
month = "5",
day = "30",
doi = "10.1007/s00126-019-00891-7",
language = "English",
journal = "Mineralium Deposita: international journal of geology, mineralogy, and geochemistry of mineral deposits",
issn = "0026-4598",
publisher = "Springer-Verlag London Ltd.",

}

TY - JOUR

T1 - Microchemical and sulfur isotope constraints on the magmatic and hydrothermal evolution of the Black Swan Succession, Western Australia

AU - Caruso, Stefano

AU - Fiorentini, Marco L.

AU - Barnes, Stephen J.

AU - LaFlamme, Crystal K.

AU - Martin, Laure A.J.

PY - 2019/5/30

Y1 - 2019/5/30

N2 - The Black Swan Succession consists of an Archean bimodal dacite-komatiite association largely dominated by ultramafic cumulates hosting a number of massive and disseminated magmatic sulfide orebodies. Although it was affected by multiple alteration events, the low degree of penetrative deformation allowed the preservation of magmatic textures and stratigraphic relationships. In this context, we apply a combined multiple sulfur isotope and microchemical approach to unravel the potential of sulfides to simultaneously retain information about their magmatic and hydrothermal history. Negative Δ33S signatures in both massive (− 0.56‰) and disseminated (− 0.66‰) sulfide orebodies reflect the assimilation of photochemically derived sulfur into the komatiite magma, which attained sulfide liquid supersaturation through the assimilation of crustal material analogous to the intercalated breccia dacite hosting colloform sulfides (Δ33S = − 0.91‰). The slightly different Δ33S signatures between disseminated and massive orebodies reflect the assimilation of different proportions of crustally derived sulfur, and imply that the respective sulfide liquids segregated from distinct komatiite magma pulses. Subsequent alteration episodes imparted to the Black Swan Succession a concentric zonation consisting of a serpentinite core and talc-carbonate margins. The Black Swan disseminated orebody extends through both alteration styles without major variations in the dominant millerite-pyrite sulfide assemblage. Pyrite in both serpentinite and talc-carbonate samples exhibits a consistent trace element signature suggesting a relative immobile behavior of Ni and Co during the percolation of the talc-carbonate fluids. Conversely, variable δ34S signatures between the two alteration styles reflect mobilization of sulfur during talc-carbonate alteration. Whereas the 2‰ range of δ34S values in serpentinites can be attributed to moderate equilibrium fractionation processes, the 10‰ range of δ34S values in talc-carbonate rocks suggests that highly oxidizing fluids promoted the mobilization of sulfur as SO42−, which decreased the δ34S of the disseminated sulfides. Furthermore, sulfur isotope and microchemical signatures of euhedral pyrite from intercalated dacitic breccia indicate that this pyrite generation was deposited from a late hydrothermal event, which is characterized by variable and least negative Δ33S signatures (between − 0.20‰ and − 0.48‰) relative to all sulfide orebodies. These features suggest that the late fluids developed in a heterogeneous hydrothermal system with a minor component of sulfur recycled from the sulfide orebodies.

AB - The Black Swan Succession consists of an Archean bimodal dacite-komatiite association largely dominated by ultramafic cumulates hosting a number of massive and disseminated magmatic sulfide orebodies. Although it was affected by multiple alteration events, the low degree of penetrative deformation allowed the preservation of magmatic textures and stratigraphic relationships. In this context, we apply a combined multiple sulfur isotope and microchemical approach to unravel the potential of sulfides to simultaneously retain information about their magmatic and hydrothermal history. Negative Δ33S signatures in both massive (− 0.56‰) and disseminated (− 0.66‰) sulfide orebodies reflect the assimilation of photochemically derived sulfur into the komatiite magma, which attained sulfide liquid supersaturation through the assimilation of crustal material analogous to the intercalated breccia dacite hosting colloform sulfides (Δ33S = − 0.91‰). The slightly different Δ33S signatures between disseminated and massive orebodies reflect the assimilation of different proportions of crustally derived sulfur, and imply that the respective sulfide liquids segregated from distinct komatiite magma pulses. Subsequent alteration episodes imparted to the Black Swan Succession a concentric zonation consisting of a serpentinite core and talc-carbonate margins. The Black Swan disseminated orebody extends through both alteration styles without major variations in the dominant millerite-pyrite sulfide assemblage. Pyrite in both serpentinite and talc-carbonate samples exhibits a consistent trace element signature suggesting a relative immobile behavior of Ni and Co during the percolation of the talc-carbonate fluids. Conversely, variable δ34S signatures between the two alteration styles reflect mobilization of sulfur during talc-carbonate alteration. Whereas the 2‰ range of δ34S values in serpentinites can be attributed to moderate equilibrium fractionation processes, the 10‰ range of δ34S values in talc-carbonate rocks suggests that highly oxidizing fluids promoted the mobilization of sulfur as SO42−, which decreased the δ34S of the disseminated sulfides. Furthermore, sulfur isotope and microchemical signatures of euhedral pyrite from intercalated dacitic breccia indicate that this pyrite generation was deposited from a late hydrothermal event, which is characterized by variable and least negative Δ33S signatures (between − 0.20‰ and − 0.48‰) relative to all sulfide orebodies. These features suggest that the late fluids developed in a heterogeneous hydrothermal system with a minor component of sulfur recycled from the sulfide orebodies.

KW - Alteration

KW - Archean

KW - Assimilation

KW - Black Swan

KW - Komatiite

KW - Magmatic nickel deposit

KW - Sulfides

KW - Sulfur isotopes

UR - http://www.scopus.com/inward/record.url?scp=85066811317&partnerID=8YFLogxK

U2 - 10.1007/s00126-019-00891-7

DO - 10.1007/s00126-019-00891-7

M3 - Article

JO - Mineralium Deposita: international journal of geology, mineralogy, and geochemistry of mineral deposits

JF - Mineralium Deposita: international journal of geology, mineralogy, and geochemistry of mineral deposits

SN - 0026-4598

ER -