PorterGeo
SEARCH  GO BACK  SUMMARY  REFERENCES
Geita

Tanzania

Main commodities: Au
Our International
Study Tour Series
The last tour was
OzGold 2019
Our Global Perspective
Series books include:
Click Here
Super Porphyry Cu and Au

Click Here
IOCG Deposits - 70 papers
All available as eBOOKS
Remaining HARD COPIES on
sale. No hard copy book more than  AUD $44.00 (incl. GST)
Big discount all books !!!


The Geita gold project is located in central northern Tanzania, some 90 km to the -west of the Lake Victoria coastal town of Mwanza. It also lies within the Geita Greenstone Belt, the northern arm of the regional Sukumaland Greenstone Belt of the Archaean Tanzanian Craton, which has a similar setting and a comparable sequence to that described at Golden Pride (see above). The Sukumaland Greenstone Belt comprises two intermittent roughly oval shaped domes with outer radii of from 80 to 140 km. The core is composed of the Lower Nyanzian mafic volcanics and sediments (see the Golden Pride description for more detail) and hosts the Bulyanhulu deposit (see above). The peripheries of the domes are dominated by the Upper Series of the Nyanzian (see the Golden Pride description for more detail) made up of BIF and intermediate and felsic volcanics. The Geita deposits are within the Upper Series. The western section of the belt, in the Geita area, is cut by regional scale Proterozoic quartz-gabbro dykes with a strong north-east trend. The area is dominated by both NW and NE structural trends, with a weaker NNW trend occupied by Karoo dolerite dykes. The greenstone belts of the Tanzanian Craton are not characterised by major regional structures as is the case in the Yilgarn and Superior Cratons, but by more localised and discontinuous structures.

Mineralisation in the belt is present in a number of forms, including 1). BIF associated ores (both near the contact with felsic pyroclastics or intrusives, and in the main body of the BIF sequence), 2). mineralisation in footwall of hangingwall felsic tuffs, 3). shear hosted mineralisation in Lower Nyanzian mafic volcanics, or as volcanogenic massive sulphides (pyrite), or 4). ferricrete enrichments over bedrock mineralisation or from erosion of the BIFs.

Historically the Geita mine has operated from earlier in the 20th century, having produced just under 30 t (0.94 Moz) of gold from 5.5 mt of ore between 1936 and 1966. In early April 2000 the previous manager Ashanti Goldfields, was joined by AngloGold and the project is now a 50:50 joint venture. The combined project has a resource of the order of 430 t (14 Moz) of contained gold with open pit grades averaging around 3.5 g/t Au. Reserves have been drilled below the open pit limits where higher grade intersections of more than 10 m @10 g/t have been encountered and the ore deposits are not closed. Production from the new Geita operation is expected to commence in late 2000.

The Geita Project now revolves around a series of deposits which includes the 1). Geita Hill and adjacent Lone Cone deposits from which the historical production was derived, 2). Nyankanga immediately to the SW, 3). the Kukuluma Hill and Matandani deposits 9 km to the NE of Geita and 4). Nyamulilima Hill some 15 km to the WSW of Geita. All of these deposits are associated with BIF rich units with intercalated andesite and felsic tuff. They occur in complex transgressive sheared zones, which at Geita and Nyankanga strike ENE and dip at 30 to 55 degrees to the north. At Kukuluma the host sequence comprises a NE dipping footwall argillaceous sequence passing up into a finely bedded, 100-150 m thick BIF-chert unit which is overlain in turn by felsic tuffs. Gold lies within two parallel shears which follow steeply dipping axial fold and limb structures, with mineralisation preferentially developed in the BIF-chert units. At the Geita deposit economic gold s found in the oxide, transition and primary sulphide intervals.

The most recent source geological information used to prepare this summary 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.


Geita

  References & Additional Information
   Selected References:
Anonymous  2000 - Joint Announcement by Anglogold and Ashanti - Ashanti to Sell a 50% Interest in Geita to Anglogold: in    Press Release    9p
Anonymous  1999 - Geita: in    Register of African Gold 1999/2000    185-186
Ashanti Goldfields  1999 - The Geita Project (includes colour pages): in    www.ashantigold.com/geita.htm and /geita1.htm-/geita7.htm    19p
Borg G  1994 - The Geita Gold Deposit in NW Tanzania - Geology, Ore Petrology, Geochemistry and Timing of Events: in    Geologisches Jahrbuch   D100 pp 545-595
Cowley P N  2001 - The discovery and development of the Geita gold deposits, northern Tanzania: in Yates K (Ed.), 2001 NewGenGold 2001, Conference Proceedings AMF, Adelaide    pp 123-135
Foster R P  1999 - Destination Africa: New Frontiers, New Mineral Exploration Opportunities: in   African Mining: Exploration and Investment Opportunities Conference, Perth, Australia: 16-17 November, 1999 AJM, Sydney    pp 1-11
Henckel, J., Poulsen, K.H., Sharp, T. and Spora, P.,  2016 - Lake Victoria Goldfields: in    Episodes,   v.39, pp. 135-154
Hester B W  1989 - Gold Mining in Tanzania: in   Gold Forum on Technology and Practices; World Gold 89; First Joint International Meeting Between SME & AusIMM Soc Min., Metall., & Explor., Littleton, CO, US    pp 104-110
Sanislav, I.V., Brayshaw, M., Kolling, S.L. Dirks, P.H.G.M., Cook, Y.A. and Blenkinsop, T.G.,  2017 - The structural history and mineralization controls of the world-class Geita Hill gold deposit, Geita Greenstone Belt, Tanzania: in    Mineralium Deposita   v.52, pp. 257279.
Walraven F, Pape J, Borg G  1994 - Implications of Pb-isotopic Compositions at the Geita Gold Deposit, Sukumaland Greenstone Belt, Tanzania: in    J. of African Earth Sciences   v18, no. 2 pp 111-121


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 takes no responsibility what-so-ever for inaccurate or out of date data, information or interpretations.

Top | Search Again | PGC Home | Terms & Conditions

PGC Logo
Porter GeoConsultancy Pty Ltd
 International Study Tours
     Tour photo albums
 Ore deposit database
 Conferences & publications
 Experience
PGC Publishing
 Our books  &  bookshop
     Iron oxide copper-gold series
     Super-porphyry series
     Porhyry & Hydrothermal Cu-Au
 Ore deposit literature
 
 Contact  
 What's new
 Site map
 FacebookLinkedin