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PGE-bearing mafic-ultramafic sills in the floor of the eastern Bushveld Complex on the farms Blaauwboschkraal, Zwartkopje, and Waterval

Maier Wolfgang D., Sliep J., Barnes Sarah-Jane, De Waal S.A. et Li C. (2001). PGE-bearing mafic-ultramafic sills in the floor of the eastern Bushveld Complex on the farms Blaauwboschkraal, Zwartkopje, and Waterval. South African journal of geology, 104, p. 343-354.

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URL officielle: http://sajg.geoscienceworld.org/content/104/4/343....

Résumé

Mafic-ultramafic sills of up to 450m in thickness occur near the contact between sedimentary and volcanic rocks of the Silverton Formation, Transvaal Supergroup, on the farms Blaauwboschkraal, Zwartkopje and Waterval, some 10km north of Waterval Boven in the Mpumalanga Province. The sills consist of peridotite, harzburgite, pyroxenite and gabbro, and may locally contain up to about 10% Ni-Cu-PGE sulphides. Metal contents of the rocks reach 0.7% Cu, 0.8% Ni, and 2 ppm PGE. Sulphides are found at variable levels within the intrusions and are interpreted to have precipitated from distinct surges of magma streaming through a conduit. This model is analogous to that proposed for the Uitkomst Complex, which hosts sulphides of broadly similar composition to the present bodies and which consists of broadly similar lithologies, apart from the presence of chromitite in the latter. The lithological and compositional similarities between the intrusions raise the possibility of undiscovered economic sulphide concentrations in the present bodies. However, olivines in most of the ultramafic rocks are undepleted in Ni, suggesting that either sulphide segregation was minor and localized, or that any metal-depleted magmas were flushed out of the conduit by undepleted magma.

Type de document:Article publié dans une revue avec comité d'évaluation
Volume:104
Pages:p. 343-354
Version évaluée par les pairs:Oui
Date:2001
Sujets:Sciences naturelles et génie > Sciences naturelles > Sciences de la terre (géologie, géographie)
Département, module, service et unité de recherche:Départements et modules > Département des sciences appliquées > Unité d'enseignement en sciences de la Terre
Mots-clés:Africa, boreholes, Bushveld Complex, gabbros, harzburgite, igneous rocks, intrusions, mafic composition, magmas, metal ores, metals, mineralization, olivine pyroxenite.
Déposé le:16 févr. 2012 22:45
Dernière modification:17 nov. 2017 00:36
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