Source of gold in Neoarchean orogenic-type deposits in the North Atlantic Craton, Greenland: Insights for a proto-source of gold in sub-seafloor hydrothermal arsenopyrite in the Mesoarchean
Given that gold (Au) mostly remained in the incipient Earth mantle until ca. 3.9–3.8 Ga, a “proto-source” of gold may have been present in the dominantly mafic crust precursor born through first-stage melting of the early Earth mantle. In south-westernmost Greenland, a fragment of the North Atlantic...
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ftethz:oai:www.research-collection.ethz.ch:20.500.11850/423875 2023-05-15T16:29:16+02:00 Source of gold in Neoarchean orogenic-type deposits in the North Atlantic Craton, Greenland: Insights for a proto-source of gold in sub-seafloor hydrothermal arsenopyrite in the Mesoarchean Saintilan, Nicolas J. Selby, David Hughes, J.W. Schlatter, Denis M. Kolb, Jochen Boyce, Adrian 2020-07 application/application/pdf https://hdl.handle.net/20.500.11850/423875 https://doi.org/10.3929/ethz-b-000423875 en eng Elsevier info:eu-repo/semantics/altIdentifier/doi/10.1016/j.precamres.2020.105717 info:eu-repo/semantics/altIdentifier/wos/000532835600009 http://hdl.handle.net/20.500.11850/423875 doi:10.3929/ethz-b-000423875 info:eu-repo/semantics/openAccess http://creativecommons.org/licenses/by/4.0/ Creative Commons Attribution 4.0 International CC-BY Precambrian Research, 343 Mesoarchean Gold Arsenopyrite Re-Os Hydrothermal Greenstone belt info:eu-repo/semantics/article info:eu-repo/semantics/publishedVersion 2020 ftethz https://doi.org/20.500.11850/423875 https://doi.org/10.3929/ethz-b-000423875 https://doi.org/10.1016/j.precamres.2020.105717 2022-04-25T14:10:32Z Given that gold (Au) mostly remained in the incipient Earth mantle until ca. 3.9–3.8 Ga, a “proto-source” of gold may have been present in the dominantly mafic crust precursor born through first-stage melting of the early Earth mantle. In south-westernmost Greenland, a fragment of the North Atlantic Craton is characterised by greenstone belts comprising mafic volcanic and magmatic rocks, and harzburgite cumulates that were emplaced at ca. <3.19–3.01 Ga (e.g., Tartoq greenstone belt). Here, combining detailed sulphide petrography with rhenium-osmium-sulphur (Re-Os-S) isotope geochemistry of individual mineral separates of arsenopyrite from gold-sulphide mineralised shear zones, we pinpoint the precipitation of ca. 3.18–3.13 Ga (Re-Os model ages) hydrothermal arsenopyrite associated and coeval with arc-related magmatism of the Tartoq Group. We consider sub-seafloor hydrothermal alteration of the oceanic crust and magmatic activity to have supplied arsenic (As), Re, and Au, to result in the precipitation of the ca. 3.18–3.13 Ga arsenopyrite with primary invisible gold. Additionally, in major shear zones in a rigid juvenile continental crust, retrograde greenschist-facies metamorphism overprinted the ca. >3.0 Ga prograde amphibolite-facies metamorphic assemblages and caused local dissolution of arsenopyrite. During this retrograde tectono-metamorphic stage, in gold-rich shear zones, the Re-Os geochronometer in arsenopyrite was reset to a Neoarchean age while invisible gold was liberated and deposited as free gold with 2.66 Ga pyrite (Re-Os isochron ages). The initial Os isotope ratios of Neoarchean arsenopyrite (187Os/188Osi = 0.13 ± 0.02) and gold-bearing pyrite (0.12 ± 0.02) overlap with the estimated 187Os/188Os ratio of the Mesoarchean mantle (0.11 ± 0.01) and preclude contribution of radiogenic crustal Os from evolved lithologies in the accretionary arc complex, but instead, favour a local contribution in Os from basaltic rocks and serpentinised harzburgite protoliths by metamorphic fluids. Thus, the ca. 2.66 Ga lode gold mineralisation identified in the North Atlantic Craton may illustrate a gold endowment in shear zones in Earth’s stabilizing continental crust at the time of the 2.75–2.55 Ga Global Gold Event, through metamorphic upgrading of bulk gold which had originally been extracted from the Mesoarchean mantle and concentrated in hydrothermal arsenopyrite deposits in oceanic crust beneath the overall reduced Mesoarchean ocean. Article in Journal/Newspaper Greenland North Atlantic ETH Zürich Research Collection Greenland |
institution |
Open Polar |
collection |
ETH Zürich Research Collection |
op_collection_id |
ftethz |
language |
English |
topic |
Mesoarchean Gold Arsenopyrite Re-Os Hydrothermal Greenstone belt |
spellingShingle |
Mesoarchean Gold Arsenopyrite Re-Os Hydrothermal Greenstone belt Saintilan, Nicolas J. Selby, David Hughes, J.W. Schlatter, Denis M. Kolb, Jochen Boyce, Adrian Source of gold in Neoarchean orogenic-type deposits in the North Atlantic Craton, Greenland: Insights for a proto-source of gold in sub-seafloor hydrothermal arsenopyrite in the Mesoarchean |
topic_facet |
Mesoarchean Gold Arsenopyrite Re-Os Hydrothermal Greenstone belt |
description |
Given that gold (Au) mostly remained in the incipient Earth mantle until ca. 3.9–3.8 Ga, a “proto-source” of gold may have been present in the dominantly mafic crust precursor born through first-stage melting of the early Earth mantle. In south-westernmost Greenland, a fragment of the North Atlantic Craton is characterised by greenstone belts comprising mafic volcanic and magmatic rocks, and harzburgite cumulates that were emplaced at ca. <3.19–3.01 Ga (e.g., Tartoq greenstone belt). Here, combining detailed sulphide petrography with rhenium-osmium-sulphur (Re-Os-S) isotope geochemistry of individual mineral separates of arsenopyrite from gold-sulphide mineralised shear zones, we pinpoint the precipitation of ca. 3.18–3.13 Ga (Re-Os model ages) hydrothermal arsenopyrite associated and coeval with arc-related magmatism of the Tartoq Group. We consider sub-seafloor hydrothermal alteration of the oceanic crust and magmatic activity to have supplied arsenic (As), Re, and Au, to result in the precipitation of the ca. 3.18–3.13 Ga arsenopyrite with primary invisible gold. Additionally, in major shear zones in a rigid juvenile continental crust, retrograde greenschist-facies metamorphism overprinted the ca. >3.0 Ga prograde amphibolite-facies metamorphic assemblages and caused local dissolution of arsenopyrite. During this retrograde tectono-metamorphic stage, in gold-rich shear zones, the Re-Os geochronometer in arsenopyrite was reset to a Neoarchean age while invisible gold was liberated and deposited as free gold with 2.66 Ga pyrite (Re-Os isochron ages). The initial Os isotope ratios of Neoarchean arsenopyrite (187Os/188Osi = 0.13 ± 0.02) and gold-bearing pyrite (0.12 ± 0.02) overlap with the estimated 187Os/188Os ratio of the Mesoarchean mantle (0.11 ± 0.01) and preclude contribution of radiogenic crustal Os from evolved lithologies in the accretionary arc complex, but instead, favour a local contribution in Os from basaltic rocks and serpentinised harzburgite protoliths by metamorphic fluids. Thus, the ca. 2.66 Ga lode gold mineralisation identified in the North Atlantic Craton may illustrate a gold endowment in shear zones in Earth’s stabilizing continental crust at the time of the 2.75–2.55 Ga Global Gold Event, through metamorphic upgrading of bulk gold which had originally been extracted from the Mesoarchean mantle and concentrated in hydrothermal arsenopyrite deposits in oceanic crust beneath the overall reduced Mesoarchean ocean. |
format |
Article in Journal/Newspaper |
author |
Saintilan, Nicolas J. Selby, David Hughes, J.W. Schlatter, Denis M. Kolb, Jochen Boyce, Adrian |
author_facet |
Saintilan, Nicolas J. Selby, David Hughes, J.W. Schlatter, Denis M. Kolb, Jochen Boyce, Adrian |
author_sort |
Saintilan, Nicolas J. |
title |
Source of gold in Neoarchean orogenic-type deposits in the North Atlantic Craton, Greenland: Insights for a proto-source of gold in sub-seafloor hydrothermal arsenopyrite in the Mesoarchean |
title_short |
Source of gold in Neoarchean orogenic-type deposits in the North Atlantic Craton, Greenland: Insights for a proto-source of gold in sub-seafloor hydrothermal arsenopyrite in the Mesoarchean |
title_full |
Source of gold in Neoarchean orogenic-type deposits in the North Atlantic Craton, Greenland: Insights for a proto-source of gold in sub-seafloor hydrothermal arsenopyrite in the Mesoarchean |
title_fullStr |
Source of gold in Neoarchean orogenic-type deposits in the North Atlantic Craton, Greenland: Insights for a proto-source of gold in sub-seafloor hydrothermal arsenopyrite in the Mesoarchean |
title_full_unstemmed |
Source of gold in Neoarchean orogenic-type deposits in the North Atlantic Craton, Greenland: Insights for a proto-source of gold in sub-seafloor hydrothermal arsenopyrite in the Mesoarchean |
title_sort |
source of gold in neoarchean orogenic-type deposits in the north atlantic craton, greenland: insights for a proto-source of gold in sub-seafloor hydrothermal arsenopyrite in the mesoarchean |
publisher |
Elsevier |
publishDate |
2020 |
url |
https://hdl.handle.net/20.500.11850/423875 https://doi.org/10.3929/ethz-b-000423875 |
geographic |
Greenland |
geographic_facet |
Greenland |
genre |
Greenland North Atlantic |
genre_facet |
Greenland North Atlantic |
op_source |
Precambrian Research, 343 |
op_relation |
info:eu-repo/semantics/altIdentifier/doi/10.1016/j.precamres.2020.105717 info:eu-repo/semantics/altIdentifier/wos/000532835600009 http://hdl.handle.net/20.500.11850/423875 doi:10.3929/ethz-b-000423875 |
op_rights |
info:eu-repo/semantics/openAccess http://creativecommons.org/licenses/by/4.0/ Creative Commons Attribution 4.0 International |
op_rightsnorm |
CC-BY |
op_doi |
https://doi.org/20.500.11850/423875 https://doi.org/10.3929/ethz-b-000423875 https://doi.org/10.1016/j.precamres.2020.105717 |
_version_ |
1766018968676466688 |