Geology

Kipushi is centred on a hydrothermal polymetallic vein deposit and is clearly associated with a set of intersecting faults estimated to be some 600-650 million years old. This makes the deposit distinct from the stratiform copper/cobalt deposits that predominate on the Congolese/Zambian Copper belt. The Kipushi deposit is located on the north limb of an anticline structure in close association with the fault zone cutting dolomitic rocks belonging to the Kundelugan system. It comprises a zone of stringer, massive and semi-massive sulfides about 600 m long and 15 to 75 m wide, striking in a north-easterly direction and dipping about 70 to the northwest. The sulfides occur in the fault plane, in joints, fractures and bedding planes in the dolomite and as subvertical chimneys in carbonate rocks. The orebody has been traced from surface down to the 1,800 m level and it is open at depth.

Orebody
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It is composed mainly of sphalerite, chalcopyrite and bornite with lesser amounts of pyrite, chalcocite, molybdenite, arsenopyrite, galena and renierite. The ore is mineralogically zoned both laterally and vertically with copper predominating in the north and at the top of the deposit and zinc strongly enriched in the south and at depth. The Kipushi deposit appears to owe its origins to the ascension of plumes of hot, metalliferous, hydrothermal fluids in a porous channelway, reacting with favourable host lithologies to cause metal deposition. The zinc grade increases with depth and this is accompanied by a decreasing copper grade. There are identified resources to depths of 1800 m with possible extensions down to 2000 to 2200 m. In addition, there is believed to be considerable potential for zinc 'stringer' orebodies.


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