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Okiep, Spektakel, Carolusberg, Nababeep, Concordia |
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Northern Cape, South Africa |
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Cu
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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 Okiep district copper mines are located within the Bushmanland mobile belt of southern Africa, within 30 km of the town of Springbok in the Northern Cape province, South Africa.
Copper orebodies have been mined within the O'okiep district since 1852, although serious mining did not commence until 1931. Total production and known reserves from these deposits as at 1985 was 2 Mt of Cu from/within 27 separate localities over an area of around 60x50 km. The total production plus reserves for the period 1940 to 1979 is 95 Mt @ 1.75% Cu. Individual mines ranging from 0.2 Mt to 37 Mt include Okiep, Spektakel, Carolusberg, Nababeep and Concordia.
The following summary has been taken from (Lombaard, etal., 1986). The copper deposits are confined to the Koperberg Suite, the youngest major group of intrusives in the district, which occurs as swarms of generally irregular, easterly trending, steep north dipping, dyke like bodies, usually 60 to 100 m wide, and seldom exceeding 1 km in continuous strike length. The Koperberg suite bodies are found within narrow linear antiformal structures (locally called 'steep structures') along which the continuity of the adjoining 'intruded' Namaqualand Metamorphic Complex rocks has been interrupted by piercement folding and faulting. In places pipe like bodies of 'mega-breccia' that generally lie along these structures are hosts to the Koperberg Suite. Steep structures, 'mega-breccias' and the Koperberg Suite all post date the major fold events.
Within the Okiep district the country rock of Namaqualand Metamorphic Complex comprises the Okiep Group (quartz-feldspar-biotite granulite and gneiss, pelitic schist, quartzite, amphibolite and calc-silicates), cut by the Gladkop Suite (two phases of fine to medium grained quartz-microcline granite gneiss), the Klein Namaqualand Suite (two phases of quartz-microcline-biotite granite gneiss, dated at 1210 Ma), the Spektakel Suite (three phases of quartz-microcline granite, dated at 1170 Ma) and finally the Koperberg Suite (1070 Ma).
The Koperberg Suite comprises mainly diorite, anorthosite and norite in order of decreasing abundance. Other rock types include lesser syenite, shonkinite, quartz anorthosite, quartz diorite, biotite diorite, glimmerite, hypersthene diorite and hypersthenite. Many of the Koperberg Suite bodies are entirely uniform, while others are composite. There is some evidence for initial anorthosite, followed by progressively more basic types. Magnetite is a ubiquitous component and in places volumetrically important. The copper is associated with the more basic lithologies.
The distribution, shape and dimensions of copper orebodies within the Koperberg Suite are extremely variable, as is the size of individual orebodies. There is a general, but not universal preference for concentration on the footwall of intrusives.
The sulphides, mainly chalcopyrite and bornite with subsidiary chalcocite, range from fine disseminations, to coarse granular, to vein aggregates, to local massive concentrations. Pyrite is widespread but in small amounts, sometimes containing traces of Co. Pyrrhotite is present in some orebodies, with associated pentlandite, while minor galena and sphalerite is found in others. Sulphides post-date silicate and oxide minerals and are present in a number of forms including, interstitially between silicate grains; as granular aggregates with silicates; along cleavage planes of hypersthene and mica; and replacing Fe-Ti-oxides. Localised hydrothermal alteration of hypersthene around sulphide grains is a conspicuous feature in little altered host rock.
For detail consult the reference(s) listed below.
The most recent source geological information used to prepare this decription was dated: 1993.
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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Cawthorn R G, Meyer F M 1993 - Petrochemistry of the Okiep Copper district basic intrusive bodies, Northwestern Cape Province, South Africa: in Econ. Geol. v88 pp 590-605
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Lombaard A F, Okiep Copper Company Limited 1986 - The copper deposits of the Okiep district, Namaqualand: in Anhaeusser C R, Maske S, (Eds.), 1986 Mineral Deposits of South Africa Geol. Soc. South Africa, Johannesburg v2 pp 1421-1445
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Maier W D 2000 - Platinum-group elements in Cu-sulphide ores at Carolusberg and East Okiep, Namaqualand, South Africa: in Mineralium Deposita v35 pp 422-429
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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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