Thesis (Ph.D.)--McMaster University (Canada), 1992. / Source: Dissertation Abstracts International, Volume: 54-02, Section: B, page: 0696.

Thesis (PhD) -- University of Western Sdyney, 2001. / "A thesis presented in accordance with the regulations governing the award of the degree of Doctor of Philosophy, University of Western Sydney" "November 2001" Bibliography: leaves 249 - 254.

Thesis (Ph.D.)--University of Wollongong, 2005. / Typescript. Disc in back pocket contains appendix 11. Includes bibliographical references.

Mémoire (M.Sc.T.)-- Université du Québec à Chicoutimi, 1993. / Document électronique également accessible en format PDF. CaQCU

Thèse (D.R.M.)--Université du Québec à Chicoutimi, 1999. / Document électronique également accessible en format PDF. CaQCU

Thesis (Ph. D.)--University of Texas at Austin, 1998. / Vita. Four folded plates in pocket. Includes bibliographical references (leaves 285-303). Available also in a digital version from Dissertation Abstracts.

The Okiep Copper District situated in the north-western Cape Province, covers some 3 000 km and is the oldest mining area in the Republic of South Africa. The O'okiep Copper Company Limited commenced production in 1940 with a proven ore reserve of 9 million tons at 2,45 % cu. Production since 1940 and present ore reserves total some 93 million tonnes at 1,08 % Cu. The rocks comprising the Okiep Copper District are of Proterozoic age and have been subdivided into a meta-volcanosedimentary succession, intruded by various sub-horizontally emplaced granitoid intrusions. The various intrusions occurred at different stages relative to the main structural and metamorphic events. The copper deposits are confined to basic rocks which are the youngest major group of intrusives in the District. They occur as swarms of generally easterly-trending, steep northdipping, irregular dyke-like bodies consisting of diorite, anorthosite and norite. The dominant silicate constituents are andesite ranging to labradorite, hypersthene, biotite and phlogopite. Copper sulphides are preferentially associated with the more basic varieties. The copper sulphides are mainly chalcopyrite, bornite and subsidiary chalcocite. The copper content of the basic rocks is erratic ranging over small distances from a mere trace to several percent. Emplacement of the cupriferous basic rocks is predisposed to a large extent by enigmatic structural features locally referred to as steep structures. The most common manifestation of steep structure deformation is typically a narrow antiformal linear feature along which continuity of the country rocks has been interrupted by piercement folding and shearing. In places, pipelike bodies of megabreccia occur along steep structures, and also act as hosts to the basic rock. Areas of steep structure are thus prime exploration targets, due to their close spatial association with the cupriferous basic rocks. Exploration techiques employed in the Okiep Copper District in~ elude regional and detailed geological mapping, geophysical surveys utilizing magnetic, gravimetric and electrical methods, as well as limited application of soil and stream-sediment geochemistry. Final evaluation is by surface and underground diamond drilling. Exploration has to date discovered 18 new mines with individual ore reserves ranging from 200 000 to 37 000 000 tonnes. All are underground operations, and the sub-level open stoping method of mining is standard.

The Damara-Katanga orogen in central-southern Africa represents an area of 1.73xl0⁶ sq. km. The region is considered one of the wealthiest metallogenic provinces in the world. Successful exploration for stratabound base-metal deposits has taken place at this particular area since the introduction of more organised methodology in the early 1920s. The genesis, location and distribution of the ore deposits are related to their tectonic settings. Geodynamic evolution of the orogen, which initially formed part of a complex Pan-African rift system, comprises the following stages rifting; downwarping, including spreading on the western portion; syn-orogeny and late-orogeny. Two major tectonic events in the history of the region have been identified: the Katangan (900-750 Ma) and the Damaran episodes (750-500 Ma). Timing of mineralisation of ore deposits has been related to the evolutionary stages of the orogen. Genetic models of the most productive deposits are briefly discussed in this dissertation. The sedimentological, geochemical, paleogeographic and structural features can be employed as geological guidelines for integrated exploration programmes. Discoveries of major deposits and prospects in the orogen are also summarised, focussing on the exploration methods employed. The cost-effective use of the exploration techniques includes the classical copper-lead-zinc soil sampling for residual soils such as those in the Copperbelt area. Airborne magnetics and electromagnetics and follow-up ground geophysics have proved successful in areas where the cover is transported in the search for shallow ore deposits such as the Matchless massive sulphides. Remote sensing, geochemical and geophysical techniques have been tried in covered areas of western Botswana. The lack of geological control makes this interpretation difficult. A detailed geological mapping and the use of geochemical and geophysical techniques has been used to delineate carbonate-hosted base-metal deposits at the Otavi Land. The more expensive traditional methods necessary for the delineation of orebodies, such as pitting, trenching and drilling, are also discussed. Using a sequential approach, a possible exploration strategy is suggested, outlining the cost-effective use of remote sensing, geochemical and geophysical techniques. Standardisation in basic geological information is required for future successful explorations in the Damara-Katanga orogen, as well as attractive mining policies. In the event of their implementation, exploration perspectives are promising, specifically in terms of ore potential.

The Lumwana copper orebody is situated 170 miles west of the Copperbelt. It is stratiform and occurs in schists regarded as part of the Katanga System older than the lower-most Copperbelt quartzite. The discovery of copper at the Lumwana Prospect was a text book example of the success of the R.S.T. Mines Services Limited prospecting techniques. These include partial geochemical analyses of soil and drainage samples, pitting, drilling and radiometric, self potential, magnetic, resistivity and induced polarization methods of geophysical exploration. The copper-bearing formations at the Lumwana Prospect occur in the inverted limb of a great recumbent fold within the Mombezhi Dome. Three periods of folding are recognized from the study of regional foliations and lineation, and the attitude of fold elements in individual folds. Each period of folding is regarded as a major pulse in the Lufilian Orogeny. The first-formed folds are isoclinal and have axial planes which strike at 160°, and dip southwest at 15°; the plunge is 11° in a direction 212° . The formation of first folds was accompanied by thrust faulting and the development of nappe structures including the great Lumwana recumbent fold. The second folds have axial planes which strike at 170° and dip west at 44°, the plunge is 12° in a direction of 192°, and the folds tend to be overturned. The third folds cut across the earlier folds at variable angles, they are overturned to the north and have axial planes which dip gently to the south. The formation of third folds was such that northward-acting stress was rotated from southeast to southwest, and relaxation of this stress resulted in the development in competent strata of joints which strike at 120° and dip steeply. At the Lumwana Prospect the northward-acting Lufilian stress is thought to have been resolved into eastward acting stress during first and second folding as a result of compression near the centre of the Lufilian Arc. The third folds are the normal Lufilian folds sub-parallel to the Lufilian Arc. Normal faulting and intrusion of gabbro along planes of these faults and the earlier thrust faults eccurred in a post-Lufilian tensional phase. In recent times warping of the formations at Lumwana has occurred on east-west axes. Statistical examination of chemical data on fifty-four composite samples of mineralized rock from drill-holes reveals that the distribution of copper, iron and sulphur is related to that of potash and soda. These relationships can be explained on sedimentological grounds since the examination of the distribution of soda and potash in these and other horizons yields no evidence of metasomatism in the mineralized horizon. Intrusive into the mineralized schists, though not found in the ore, are thin amphibolites and a large serpentinite which contains relict olivine and bronzite. This is the first recorded occurrence of ultrabasic rocks in the Lower Roan Group of the Katanga System in this part of Zambia. Study of all formations at the Lumwana Prospect reveals that they have been metamorphosed in the epidote-amphibolite facies of regional metamorphism. Mineral assemblages indicative of the amphibolite facies are found in sheared rocks, and metamorphism in competent parts of the Upper Roan-Mwashia has been confined to the greenschist facies. Temperatures of metamorphism are estimated to have been between 250° and 280°C, and pressures are likely to have exceeded 6 kilobars. Evidence of metasomatism, absent in the Lower Roan, is found in the examination of the Upper Roan-Mwashia formations. Metasomatism includes scapolitization and albitization and is related to the intrusion of gabbro into these sediments, but does not necessarily involve exogenous material. The sulphide minerals identified are bornite, chalcocite, digenite, covellite, chalcopyrite, cubanite, valleriite, carrollite, pyrite and pyrrhotite. Intergrowths of these minerals have resulted from metamorphism at temperatures slightly in excess of 235°C. The copper sulphides are distributed zonally in the orebody with chalcocite- bornite ore where the mineralized schist is thin, and chalcopyrite- cubanite-pyrite ore where it is thick. Vertically the body contains horizons with sulphides relatively rich in copper at the top and bottom, and an intermediate zone with sulphides leaner in copper. This zonal distribution is considered to be evidence for syngenetic deposition of copper during successive cycles of transgression and regression. Ore genesis at Lumwana is closely related to genesis of the Copperbelt and Katanga orebodies. The Zambia-Katanga province is considered to have been enriched in copper epigenetically prior to the formation of the present-day orebodies. Reworking of these cupriferous rocks and some early-formed syngenetic deposits of which Lumwana is one, is considered to have played a major role in producing the present-day copper orebodies.

In recent years our understanding of the genesis of porphyry copper systems has advanced to a sufficient level to be able to construct predictive models that enhance exploration for these deposits. Our understanding of primary and secondary geochemical dispersion around these deposits is not so advanced as variables such as climate and topography cause geochemical patterns to be distorted or masked at surface with the result of different deposits having quite different geochemical characteristics. In this study the geology and geochemistry of a porphyry copper-molybdenum from the Canadian Cordillera is examined with the aim of demonstrating how primary geochemical patterns are affected by the development of a supergene enrichment blanket and leached capping. Topographic controls on the extent of leaching and supergene enrichment are also explored. The Berg porphyry copper-molybdenum deposit is in the Tahtsa Mountain Ranges, approximately 84 km southwest of Houston, central British Columbia. Mineralized zones are centered on a circa 50 Ma composite quartz monzonite stock. Hydrothermal alteration zones are similar to those of the classic model by Lowell and Guilbert. Central zones are potassic (orthoclase and biotite) while peripheral zones are propylitic (chlorite, epidote, carbonate). Intense phyllic alteration (quartz, sericite, pyrite) occurs at the north and south margins of the stock. Hypogene mineralization (characterized by pyrite, chalcopyrite and molybdenite) is concentrated in an annular zone straddling the quartz monzonite contact. Best grades are localized in altered quartz diorite and altered and hornfelsed Telkwa Formation (Hazelton Group) volcanic rocks at the east side of the deposit. The nature of these altered hornfelsed rocks has been a subject for much debate in previous studies. One school of thought suggests that they are part of a hornfels aureole associated with the quartz diorite. Others suggest that it is an alteration zone associated with the quartz monzonite stock. Thirteen diamond drill holes on a north south cross section of the deposit were logged (GEOLOG) and sampled. Outcrop samples were collected where possible close to each drill hole. Major elements were determined by XRF, trace metals by flame AAS and fluorine by specific ion electrode. A sequential extraction was used to study the distribution of copper between different host minerals. The origin of the hornfelsed rocks is solved by field mapping and geochemistry. In the field cross cutting relationships show that the quartz diorite predates the stock and that the hornfels zone is spacially related to it. Major element binary and ternary plots demonstrate that significant amounts of potassium have been added to these rocks in the mineralized zone. This implies that biotite alteration was superimposed onto an earlier hornfels. Trace metal data was partitioned into anomalous and background populations with probability graphs. In the hypogene zone Cu, Mo and Ag occur in an annular zone corresponding with the mineralogically defined potential ore zones. Fluorine is anomalous over the area of the potassic alteration zone. Lead and zinc are anomalous in peripheral haloes around the potential orebodies. These zones can be traced to surface through an extensive supergene enrichment blanket and leached capping. Three zones of supergene mineralization are recognized: supergene sulphide (covellite, digenite, chalcocite), supergene oxide (malachite/azurite, cuprite, tenorite, native Cu) and leached capping. Sulphides are the dominant host for Cu throughout most of the deposit but locally on steep slopes where supergene oxide is developed Cu is hosted in carbonate and oxide minerals. Enrichment or depletion of elements in the supergene is demonstrated with interelement ratios. Enrichment factors can be derived in two ways: a) by ratioing supergene values to hypogene values, or, b) by ratioing to a constant (e.g. TiO₂ ) for each zone and then ratioing this value between zones. Enrichment factors of <1 therefore imply depletion and >1, enrichment (1=hypogene grade). Results show that all elements (studied) are enriched in the supergene sulphide and oxide zones. In the leached cap Cu, Mn and Zn are depleted while Mo, Pb and Ag are significantly enriched. These elements are incorporated into immobile limonite mineral's (ferrimolybdite, jarosite, goethite etc.). / Science, Faculty of / Earth, Ocean and Atmospheric Sciences, Department of / Graduate