Mesoarchaean Gold Mineralisation in the Barberton Greenstone Belt: A Review

Détails

ID Serval
serval:BIB_1089D35CA018
Type
Partie de livre
Collection
Publications
Titre
Mesoarchaean Gold Mineralisation in the Barberton Greenstone Belt: A Review
Titre du livre
Regional Geology Reviews
Auteur⸱e⸱s
Agangi Andrea, Hofmann Axel, Eickmann Benjamin, Marin-Carbonne Johanna
Editeur
Springer International Publishing
Lieu d'édition
Cham
ISBN
9783319786513
9783319786520
ISSN
2364-6438
2364-6446
Statut éditorial
Publié
Date de publication
2019
Editeur⸱rice scientifique
Kröner Alfred, Hofmann Axel
Pages
171-184
Langue
anglais
Résumé
The Barberton Greenstone Belt hosts abundant structurally controlled gold mineralisation of Mesoarchaean age. More than 300 gold occurrences have been reported, although most of the gold production so far (>350 tonnes Au) has come from a handful of deposits located along the northern margin of the greenstone belt. Most deposits are hosted by greenschist-facies metasedimentary and metamafic rocks, with the notable exception of the amphibolite-facies rocks at New Consort mine. Mineralisation is associated with quartz--carbonate veins that truncate major compressional structures at the greenstone belt scale. The age of mineralisation is loosely constrained at circa 3080--3030 Ma, based on U--Pb dating of hydrothermal rutile and titanite. In greenschist-facies deposits, the ore assemblage is dominated by pyrite and arsenopyrite, which contain up to thousands of ppm of `invisible' gold, Ni--As--Sb sulphides and native gold. At New Consort mine, mineralisation includes massive replacement-style ore and vein-hosted or disseminated types. Both structural studies in the field and microstructural observation point to a multistage ore deposition process, which is reflected in the re-activation of brittle to ductile structures and the overprinting of sulphide assemblages. The presence of mass-independently fractionated S isotopes ($\Delta$33S{\thinspace}={\thinspace}--0.6 to +1.0{\texttenthousand}) in pyrite from Sheba and Fairview mines suggests that hydrothermal fluids mobilised S from volcanic and sedimentary rocks of the greenstone belt and places constraints on the origin of the Au itself.
Création de la notice
27/01/2020 15:13
Dernière modification de la notice
27/01/2020 15:14
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