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Source of gold in Neoarchean orogenic-type deposits in the North Atlantic Craton, Greenland: Insights for a proto-source of gold in sub-seafloor

Saintilan, N.J.; Selby, D.; Hughes, J.W.; Schlatter, D.M.; Kolb, J.; Boyce, A.

Abstract:
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 goldsulphide 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. ... mehr

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Verlagsausgabe §
DOI: 10.5445/IR/1000118158
Veröffentlicht am 03.06.2020
Cover der Publikation
Zugehörige Institution(en) am KIT Institut für Angewandte Geowissenschaften (AGW)
Publikationstyp Zeitschriftenaufsatz
Publikationsmonat/-jahr 07.2020
Sprache Englisch
Identifikator ISSN: 0301-9268
KITopen-ID: 1000118158
Erschienen in Precambrian research
Band 343
Seiten Art. Nr.: 105717
Schlagwörter Mesoarchean, Gold, Arsenopyrite, Re-Os, Hydrothermal, Greenstone belt
Nachgewiesen in Web of Science
Scopus
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