Khusib Springs |
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Namibia |
Main commodities:
Zn Cu Pb Ag Sb
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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 Khusib Springs Cu-Zn-Pb-Ag-(As-Sb-Ge) deposit is located approximately 40 km southeast of Tsumeb in in the Otavi Mountain Land of eastern Namibia.
It is a small though high-grade carbonate-hosted, 'Tsumeb-type', base metal deposit containing approximately 0.3 Mt @ 10% Cu, 1.8% Pb and 584 ppm Ag.
It comprises a lens-shaped sulphide orebody that is elongated parallel to bedding and is up to 10 m thick. This lens dips south at 40° and is up to 110 m in down dip extent and has a long dimension of nearly 150 m.
The sulphides replace locally brecciated limestone of the lower Tsumeb Subgroup (a member of the Neoproterozoic Damara Supergroup) on the northern limb of a large northeast-trending synclinal structure. The orebody is surrounded by a prominent halo of dolomite alteration.
Drill intersections through the deposit reveal that the uppermost 2 m are enriched in Zn (up to 5%) and Ag (up to 3350 ppm), but is lower in Ge (<30 ppm) than the central and lower parts of the orebody, which are enriched in Ge (up to 200 ppm) and Pb (up to 7%).
The massive sulphide ore comprises a texturally complex mineral assemblage dominated by Zn-rich tennantite, enargite, galena and pyrite. Fe-poor sphalerite is abundant in the uppermost part of the orebody and in the footwall where it forms a prominent zone of disseminated sphalerite ± chalcopyrite ± pyrite. The upper part of the massive ore is also characterised by late-stage phases including tetrahedrite, Ag-bearing tennantite, pearceite-polybasite and native silver. The central and lower sections comprise tennantite-enargite-galena concentrations with variable pyrite, but little or no sphalerite.
Melcher et al., (2006) proposed a polyphase paragenesis involving three successive stages, namely: i). An early sphalerite-pyrite-(-chalcopyrite-bornite) mineralisation, replaced by ii). tennantite, enargite, galena and Ge-bearing colusite, and iii). A late stage which overprints parts of the orebody at lower temperatures leading to precipitation of 'schalenblende' (Cu- and Ag-rich), digenite, tetrahedrite and pearceiteŠpolybasite.
The most recent source geological information used to prepare this decription was dated: 2006.
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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Melcher F, Oberthur T and Rammlmair D, 2006 - Geochemical and mineralogical distribution of germanium in the Khusib Springs Cu-Zn-Pb-Ag sulfide deposit, Otavi Mountain Land, Namibia : in Ore Geology Reviews v28 pp 32-56
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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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