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Golden Pride |
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Tanzania |
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Au
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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 Golden Pride deposit is located in central northern Tanzania, some 200 km to the south of the Lake Victoria coastal town of Mwanza and 750 km north-west of Dar es Salaam (#Location: 4° 5' 12"S, 33° 11' 59"E).
It is within the 2800 to 2500 Ma Nzega Greenstone Belt which is part of the granite-greenstone terrane of the Archaean Tanzanian Craton. The Tanzanian Greenstones are divided into the older Nyanzian System which hosts all of the major deposits of the craton, and the younger Kavirondian System. The Nyanzian System is, in turn, divided into a Lower Series of basalt, andesite and dacite with subordinate BIF and clastic sediments. These are overlain by an Upper Series of characterised by felsic volcaniclastics, ferruginous chert, BIF and shale. Unconformably over these are the conglomerates, coarse arkosic grits and quartzites of the Kavirondian System. The extrusives of the Nyanzian System are from 2.8 to 2.9 Ga, while the granites are variously between 2.57 and 2.53 Ga. Golden Pride and the other significant deposits are hosted by the Nyanzian System.
The Golden Pride deposit is located near the southern margin of the Nzega Greenstone Belt, within felsic to intermediate volcaniclastics and argillites, comprising a thick basal sequence of interbedded quartzose arkosic sandstones and pelites intruded by a massive medium grained dacite body with minor intercalated mafics near the top. These are overlain by a 100 to 200 m thick dolerite sill that is followed by 500 to 700 m of rhyolitic volcanics. The upper most unit is a 1000 to 1500 m succession of argillite and arenite separated from the underlying rhyolites by a thin chlorite schist. These sediments have intercalated volcaniclastics increasing upwards. The east west trending, south-west dipping Golden Pride Structure cuts the stratigraphy near the top of the Upper sequence at a low angle, near the transition from dominantly siliciclastics lithologies to the felsic/intermediate volcaniclastics. The sequence in the immediate vicinity of mineralisation comprises laminated chert and oxide facies BIF interbedded with volcaniclastics, primarily sub-aerial volcaniclastics with intercalated terriginous sediments, all overlying a locally thick (20 m) conglomerate. The BIFs are overlain by felsic tuffites and argillites. In the 80 m thick ore zone the primary rock types have been obliterated by intense shearing accompanied by strong silica and carbonate alteration. The tuffaceous units form the main host, with the coarser members having undergone the most brittle deformation. Rocks within the shear zone have been totally oxidised to a depth of 75 m.
The hydrothermally emplaced mineralisation is accompanied by carbonate alteration, silicification and chlorite-biotite-pyrrhotite alteration. Carbonatisation is the most widespread and comprises calcite with minor ankerite and dolomite. It is more intense in the immediate footwall of the ore, although there is no apparent correlation with gold mineralisation. There is however, a positive correlation between gold and silicification, particularly when the alteration is accompanied by arsenopyrite and pyrrhotite. It is best developed in the core of shear zones, and post dates carbonatisation. In its late stages it is accompanied by hydraulic brecciation and locally high grades of gold. Chlorite-biotite-pyrrhotite alteration is more intense in intervals of strong shearing in the hangingwall intermediate to mafic volcanics and is cut by quartz veining coeval with the silica alteration.
Approximately 80% of the gold in reserves is oxide ore, two thirds of which is in the saprolite zone, with gold being associated with characteristic yellow-brown limonitic clays. The non-mineralised wall rocks are generally strongly hematitic and variably sericitic. The primary mineralisation is clearly sympathetic with the host shear, associated with strong alteration of all three types. Arsenopyrite is an important correlative of gold, occurring as fine grained late stage crystals overprinting all of the other alteration.
The main zone of mineralisation has a strike length of 2.7 km and remains open at depth. In 2000, the operation was expected to produce over 5.5 t (180 000 oz) of gold per year at a cash cost of USD 200/oz.
The proven+probable reserve in 1998 was 10.9 Mt @ 3.1 g/t Au within a global resource of 33.4 Mt @ 2.56 g/t Au, for a total of 85 t (2.7 Moz) of gold.
The mine was closed in late 2013 after having produced 68.5 tonnes of gold.
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.
Golden Pride
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Anonymous 1999 - Golden Pride: in Register of African Gold 1999/2000 pp 186-187
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Henckel, J., Poulsen, K.H., Sharp, T. and Spora, P., 2016 - Lake Victoria Goldfields: in Episodes, v.39, pp. 135-154
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Stevens R, Kennedy R 1998 - The Golden Pride Gold Deposit, Tanzania: in Africa: Geology and Mineral Exploration AIG Bull. 25, 1998 pp 3-8
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Vos I M A, Bierlein F P, Standing J S and Davidson G 2009 - The geology and mineralisation at the Golden Pride gold deposit, Nzega Greenstone Belt, Tanzania: in Mineralium Deposita v.44 pp. 751-764
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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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