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Vergenoeg |
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Limpopo (Northern) Province, South Africa |
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F Fe
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Super Porphyry Cu and Au
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IOCG Deposits - 70 papers
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All papers now Open Access.
Available as Full Text for direct download or on request. |
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The Vergenoeg fluorite mine in South Africa is associated with a discordant hematite rich breccia pipe. It has zones of associated copper mineralisation and is interpreted to belong within the Iron-Oxide Copper-Gold family of deposits.
The discordant volcanic pipe and associated surrounding pyroclastic and sedimentary rocks of the Vergenoeg suite are hosted by the felsic rocks of the Rooiberg Group, which constitutes the roof of the Bushveld Complex. The volcanic pipe is situated at the intersection of strong aerial photo and magnetic lineaments, close to the centre of the four lobes of the Bushveld Complex in the Republic of South Africa. The Vergenoeg suite constitutes an uppermost stratiform sedimentary unit, followed by fragmental, conformably stratified hematite and hematite-fluorite units. This is underlain by a breccia-agglomerate and then a basal unit of ignimbrites. A discordant volcanic pipe completes the suite.
The Vergenoeg volcanic pipe has a vertical downward tapering shape, with a surface diameter of about 900 m, narrowing sharply in depth to where it is still open-ended at more than 650 m. Horizontal zoning is observed within the pipe, with a hematite-fluorite or gossan cap at surface, followed by a deeper zone of unoxidised magnetite-fluorite, then a magnetite-fayalite transition interval and finally a fayalite zone at the deepest levels. Fluorite, siderite and pyrite veins, dykes and lenses are present throughout all zones.
Contacts between zones are gradual but are sharp with the felsic host rock. Felsite breccias, cemented by fluorite, siderite and pyrite are found at depth. Although iron oxide, fluorite and fayalite assemblages constitute 90% of the mineral content, accessory siderite, iron-sulphides and Rare Earth Elements (REE) are common. Levels of most base metals, and in certain areas uranium and thorium, are anomalous. Fluorite and iron oxides are present in variable quantities throughout the pipe but fluorite decreases with depth, with resultant increases in iron oxides and fayalite. Fluorite occurs in a massive as well as disseminated form. The fluorite ore body is essentially up to a depth of 360 m with a resource estimate of 174 Mt at 28.1% CaF2. The iron resource is in the order of 195 Mt at 42% Fe.
Petrogenetically, this rock suite relates to the felsic rocks of the Bushveld Complex, which are regarded as the source of mineralisation. This is in accordance with the family of iron oxide copper-gold type deposits, which are mostly related to granites. Other features that Vergenoeg has in common with the related deposits are massive iron oxide mineralisation, often associated with breccias, and anomalous sulphides and REE mineralisation. Hydrothermal alteration is also distinctive.
The most recent source geological information used to prepare this decription was dated: 2001.
This description is a summary from published sources, the chief of which are listed below.
© Copyright Porter GeoConsultancy Pty Ltd. Unauthorised copying, reproduction, storage or dissemination prohibited.
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Borrok D M, Kesler S E, Boer R H, Essene E J 1998 - Vergenoeg Magnetite-Fluorite deposit, South Africa: support for a hydrothermal model for massive Iron Oxide deposits: in Econ. Geol. v93 pp 564-586
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Fourie P J, 2000 - The Vergenoeg Fayalite Iron Oxide Fluorite Deposit, South Africa: Some New Aspects: in Porter T M (Ed), 2000 Hydrothermal Iron Oxide Copper-Gold & Related Deposits: A Global Perspective PGC Publishing, Adelaide v.1 pp. 309-320
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Porter GeoConsultancy Pty Ltd (PorterGeo) provides access to this database at no charge. It is largely based on scientific papers and reports in the public domain, and was current when the sources consulted were published. While PorterGeo endeavour to ensure the information was accurate at the time of compilation and subsequent updating, PorterGeo, its employees and servants: i). do not warrant, or make any representation regarding the use, or results of the use of the information contained herein as to its correctness, accuracy, currency, or otherwise; and ii). expressly disclaim all liability or responsibility to any person using the information or conclusions contained herein.
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