Geological factors affecting tonnage-grade relationships in orebodies of the Zambian Copperbelt
- Authors: McCulloch, Alan B
- Date: 1981
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:21151 , http://hdl.handle.net/10962/6617
- Description: The occurrence of a major metalliferous province in Zambia and Zaire is a reflection of geological processes operating in a specific environment during a particular period. The size of orebodies, their grade, mineralogy, beneficiation characteristics and therefore the amount of metal produced are all ultimately functions of the geology of the ores. This study is primarily concerned with the effect geology has on tonnage-grade relationships of ore in situ on the Zambian Copperbelt. Five major topics related to ore tonnage and grade are reviewed here: -behaviour of copper and cobalt in surficial environments. -geological setting and gross lithostratigraphic relationships of mineralization. -characteristics of known orebodies. -geological factors affecting mining and beneficiation of ore. -orebody limits and estimation of tonnage and grade. In addition, the historical background to the problems discussed here is briefly described, and some general aspects of the evaluation, mining and beneficiation of Copperbelt ores are considered in relation to metal production.
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- Date Issued: 1981
Geology and ore reserve estimation of the Witwatersrand-type gold deposits with specific reference to the Welkom Goldfield
- Authors: Ainslie, L C
- Date: 1981
- Subjects: Mines and mineral resources -- Statistical methods Mine valuation -- Statistical methods Gold ores -- Geology Witwatersrand Basin (South Africa) Ores -- Sampling and estimation -- Statistical methods
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4911 , http://hdl.handle.net/10962/d1001571
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- Date Issued: 1981
A review of landscape development and erosion cycles in southern Africa
- Authors: Corbett, Dudley Harold
- Date: 1979
- Subjects: Landscape changes -- Africa, Southern Erosion -- Africa, Southern
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4899 , http://hdl.handle.net/10962/d1001558
- Description: The study of landforms has, to a large extent been neglected by exploration geologists. This is surprising because field geology is intimately related with landforms of one type or another. An understanding of the geomorphological history of a particular area will assist in the appreciation of the surficial environment, the processes of weathering, soil formation and duricrust (calcrete , ferricrete silcrete) formation. This has direct application in planning and interpreting geochemical sampling programmes. In order to understand the evolution of landforms it is necessary to study slope development in some detail. Agents of erosion and denudation constantly at work, remove detritus from hillcrests down to the drainage lines which form the local base level from whence material is transported down to the sea. The system is one of dynamic equilibrium, and the concept of grade is important in understanding hillslope evolution. Thus Section (1) of this discussion deals with past and present theories of hillslope evolution. Very little work has been done recently on the geomorphology of Southern Africa and the presently accepted classification of land surfaces is based on the work of Prof. L.C. King (numerous publications). However, through the more recent work of De Swardt and Bennet (1974) on the geomorphology of Natal, it is apparent that the present system of landform classification in Southern Africa requires widespread revision. The relationship of erosion cycles in Southern Africa to the late Jurassic-early Cretaceous break-up of Gondwanaland has received insufficient attention in the past. Erosion cycles bear an intimate relationship to offshore Cretaceous and Tertiary-Recent sedimentation. Valuable information on these sediments has only recently become available as a result of offshore exploration for oil. The findings of De Swardt and Bennet (1974) are summarized in Section (2) and the present land surface classification of Southern Africa is reviewed. Finally, some suggestions on a new interpretation of land surfaces in Southern Africa are given.
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- Date Issued: 1979
Gold mineralization in archaean cherts and iron-formations a review of the economic geology
- Authors: Bellamy, R E S
- Date: 1979
- Subjects: Gold ores -- Geology -- South Africa , Gold mines and mining -- South Africa , Greenstone belts -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4968 , http://hdl.handle.net/10962/d1005580 , Gold ores -- Geology -- South Africa , Gold mines and mining -- South Africa , Greenstone belts -- South Africa
- Description: The distribution of gold in igneous rocks and minerals is described and discussed. Not all the gold in igneous rocks is contained within early formed crystal lattices. Evidence that gold can be associated with late stage crystallizing phases is described. It is concluded that some of the gold in hydrothermal and volcanogenic deposits may have come from a primary magmatic source rather than having been leached from solid country rock. Gold is probably transported as chloride complexes at temperatures greater than about 300°C. At lower temperatures it is probably transported with other metals as sulphide and thio-sulphide complexes. The precipitation of gold from the transporting medium is brought about by changes in the physico-chemical conditions within that medium. Decrease in pressure is probably not a major cause of precipitation in volcanogenic environments. The geology of volcanogenic iron-formations is described and discussed, relative to the development of greenstone belts. Oxide facies iron-formations were formed in shallow oxidizing environments. They are associated with volcanogenic and clastic sediments. Sulphide facies iron-formations were precipitated in the deeper parts of geosynclinal structures. They are associated with mafic and ultramafic rocks similar to modern oceanic volcanic assemblages. Carbonate facies iron-formations were deposited in the regions between oxide facies and sulphide facies. Other banded iron-formations are found associated with base metal massive sulphide deposits related to arctype volcanic centres. These deposits are found in the regions where carbonate facies iron-formations were formed. Exploration for and exploitation of gold deposits in Archaean iron-formations are discussed. Geochemical exploration programmes are aided by the association of gold with trace amounts of base metals. Geophysical exploration methods that can be employed include magnetometer, I.P. and E.M. surveys. The metallurgical treatment of the ores should include "roasting" because a large proportion of the gold occurs as submicroscopic grains within sulphide mineral crystals.
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- Date Issued: 1979