List of Titles

The North Break Zone of the late Precambrian Otavi carbonate platform sequence in Namibia: stratigraphic setting, petrography and relationship with Tsumeb Cu-Pb-Zn deposit

- Theron, Salomon Johannes

Authors: Theron, Salomon Johannes
Date: 2014-04-24
Subjects: Carbonate rocks - Namibia - Otavi Mountain Land , Carbonate rocks - Namibia - Tsumeb , Geology, Stratigraphic - Precambrian , Petrology - Namibia - Otavi Mountain Land
Type: Thesis
Identifier: http://ujcontent.uj.ac.za8080/10210/375459 , uj:10853 , http://hdl.handle.net/10210/10360
Description: M.Sc. (Geology) , The main objective of this study was to characterize the North Break Zone of the Otavi Mountain Land, Namibia in terms of stratigraphy and petrography and to investigate its relationship with the Tsumeb ore body and other mineralized prospects in the immediate vicinity of Tsumeb. The Late Proterozoic Otavi carbonate platform sequence is famous for its base metal deposits. The North Break Zone is a stratabound zone of sporadic mineralization, brecciation and silicification occurring in the lower part of Iithozone T6 of the Hoffenberg Formation (Tsumeb Subgroup). It intersects the pipe-like Tsumeb Cu-Pb-Zn-Ag ore body at a depth of about 900m below surface. Where the North Break Zone intersects the Tsumeb ore body large massive ore associated with calcitized dolomite, dolomite breccia as well as feldspathic sandstone lenses occur. These features extend along strike and dip outside the normal dimensions of the Tsumeb ore body. The genesis of the Tsumeb ore body is poorly understood. The conventional model is that meteoric fluids circulated through the so-called North Break Zone paleo-aquifer, dissolving carbonate and giving rise to solution collapse and eventually the creation of the Tsumeb karst pipe. However, no direct evidence is available to support this model. This study was devised to critically evaluate the relationship between the North Break Zone and formation of the Tsumeb ore body. The study entailed field mapping, detailed sampling of the stratigraphic sequence and ore bodies, white light, reflected light, UV/blue light and cathodoluminescence petrography. Cathodoluminescence proved to be the most effective petrographic tool for differentiating various carbonate phases. The North Break Zone is defined as a 10 to 14m thick chert free oolitic to intraclastic dolomitic grainstone, stromatolite and mudstone unit, in which discontinuous lenses of mineralized secondary quartz are present. It is interbedded with dark grey cherty micritic dolomite of Lithozone T6 of the HOffenberg Formation. Minor calcification, Cu-Pb-Zn mineralization and manganese and iron enrichment are associated with the quartz-rich bodies. The mineralized quartz bodies are only present up to 2.5km to the west and 2.6km to the east of the Tsumeb ore body. The petrographic study indicated that 1) the epigenetic sequence of carbonate alteration, precipitation of new carbonate phases and mineralization is virtually identical in all Cu-Pb-Zn occurrences and 2) that the mineralization is closely associated with Mn-bearing brightly luminescent (CL) carbonates. Earlier Cu-Pb-Zn sulphide mineralization is associated with Mn-bearing bright red luminescent sparry dolomite (dolomite IIIB). Late stage Cu-arsenate, oxide and silicate mineralization is associated with an episode of Mn-bearing bright yellow luminescent calcite (calcite II) which also causes dolomitization of the associated dolomites. A very simple paragenetic model of mineralization is proposed. The earliest is defined by pre-mineralization calcite (calcite I) vein formation with associated dolomitization. This phase is followed by deposition of kerogen luminescent Mn-bearing dolomite IIIB - quartz and Cu-Pb-Zn sulphides representing the main mineralization event. It is followed by a late mineralization event composed of Mn-bearing calcite (calcite II) with associated Cu-arsenates, oxides and silicates. Supergene alteration is represented by the precipitation of very late stage non-luminescent Mn and Fe-poor calcite (calcite III) and quartz without any associated Cu-Pb-Zn mineralization. The sequence of mineralization is explained by the evolution of a single hydrothermal fluid, from relatively cold to hot and then back to cold, during a major period of fluid migration through the carbonate platform sequence. The North Break Zone probably never acted as a paleo-aquifer for fluids that formed the Tsumeb ore body. Rather hydrothermal fluids moved from the Tsumeb ore body into the North Break Zone. Hydrothermal fluids may have been derived from the Damara orogen to the south of Tsumeb during a period of tectonic loading and thrust deformation.
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Petrography and geochemistry of the pre-Mapedi “bostonite” dykes and sills in the Kalahari Manganese Field, Northern Cape Province

- Monareng, Batobeleng Fisah

Authors: Monareng, Batobeleng Fisah
Date: 2016
Subjects: Dikes (Geology) - South Africa - Northern Cape , Sills (Geology) - South Africa - Northern Cape , Intrusions (Geology) - South Africa - Northern Cape , Manganese ores - Geology - South Africa - Northern Cape
Language: English
Type: Masters (Thesis)
Identifier: http://hdl.handle.net/10210/235816 , uj:24123
Description: M.Sc. (Geology) , Abstract: Mafic dykes and sills intruding and affecting ore deposits are a well-known phenomenon around the world. The role played by magmatic hypogene fluids globally in the genesis of high-grade hematite ore is well-recognized. In the Northern Cape Province of South Africa, a series of intrusions have been emplaced in association with various sedimentary-hosted iron and manganese deposits. In the Kalahari Manganese Field (KMF) of the Northern Cape Province, the intrusions are referred to as “bostonites”.These dykes and sills are pre-Mapedi in age and contact metamorphosed the ore resulting in a general decrease of ore quality. The main aim of the study is to characterize the “bostonite” dykes and sills more extensively than previously by determining whether they are related to the same magmatic event and by evaluating the style of alteration that affected the “bostonite” chemistry. Comparison with the previously studied “bostonites” and the well-known large igneous provinces of the Kaapvaal Craton was made to determine the comagmatism. A paleoweathering profile on the mafic intrusive rocks (so-called “Bostonite”) was intersected during the exploration drilling of the Avontuur Deposit and provides an opportunity to describe the behavior of major, trace and REE in weathered rock relative to the unweathered parent rock. This weathering profile developed below the basal Gamagara/Mapedi unconformity overlying the iron formation (IF) and manganese formation (MF) of the Hotazel Formation and marks the base of Olifantshoek group. The “bostonites” of the Main Kalahari Deposit are composed predominantly of pyroxenes (diopside and augite), plagioclase (labradorite and andesite), Fe-Ti oxides (ilmenite, titanomagnetite) and minor rutile. The “bostonites” of the Avontuur Deposits, on the other hand, are composed predominantly of pyroxene (augite), plagioclase (albite) and Fe-Ti oxides (ilmenite, titanomagnetite, titanite). Based on the geochemistry, “bostonites” of both the Main Manganese and Avontuur Deposits are characterized by low Mg# indicating an evolved nature of the magma, as well as low Cr, Co and Sc signifying fractionation of the mafic minerals within the magma chamber. These mafic intrusives are characterized by negative Sr, Nb and Ta anomaly and positive K and Pb...
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Multi-pronged approach to constrain the age of the Molopo Farms layered igneous complex, Northern Cape Province and Southeastern Botswana

- Ravhura, Livhuwani Given

Authors: Ravhura, Livhuwani Given
Date: 2016
Subjects: Geochronology , Geology - Botswana , Geology - South Africa - Northern Cape , Igneous rocks - Botswana , Igneous rocks - South Africa - Northern Cape , Molopo Farms Complex (Botswana and South Africa)
Language: English
Type: Masters (Thesis)
Identifier: http://hdl.handle.net/10210/235897 , uj:24133
Description: M.Sc. (Geology) , Abstract: This study presents the first detailed major- and trace element geochemical and geochronological studies of the Molopo Farms Complex (MFC), situated in the Northern Cape Province, South Africa and south eastern Botswana. The rocks of the MFC are gabbro, serpentinite, pyroxenite and intrudes into sedimentary host rocks, these rocks are medium- to coarse grained. The mafic igneous rocks of the MFC are dominantly sub-alkaline tholeiitic in composition and characterized as basaltic andesite. The MFC is completely covered by Cenozoic sediments of the Kalahari Formation and it is only known through intersection in exploration drill core and geophysical data. It is thought that the MFC has intruded the sedimentary succession of the Paleoproterozoic Transvaal Supergroup. Unlike other layered complexes (Bushveld Complex, Stillwater Complex, etc.), no detailed geochemical studies have been done on the MFC. At present, the available age is the poorly constrained at 2044±24 Ma (Rb-Sr errorchron age) and for that reason, and the fact that it is a layered igneous complex it has been correlated with Bushveld Complex. However, this age and correlation are poorly constrained. This study provides additional data on the geochemical composition of the igneous rocks to fully understand the geochemical signature of the igneous rocks of the MFC, a baddeleyite age on a gabbro from the complex and also detrital zircon age data on the sedimentary country rocks. The geochemical signature of the MFC has been compared to that of other magmatic events (Bushveld Complex, Moshaneng dykes and Post Waterberg sills) to evaluate the similarities in composition. The MFC is characterized by an enrichment in LREE relative to the HREE and shows negative Eu, Nb(Ta), P, Ti and positive K, Pb and U anomalies. This geochemical signature compares well with that of the B1-magma of the Bushveld Complex. An age of 2052±16 Ma, obtained from U-Pb baddeleyite dating, has been interpreted to be the emplacement age of the MFC. This age is within error with the 2054.4±1.3 Ma accepted age of the Bushveld Complex. The maximum age of sedimentary country rock into which MFC intrudes has been better constrained by U-Pb detrital zircon dating. The youngest concordant zircon ages obtained are between 2018±39 and...
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Die sedimentologie en stratigrafie van die Ecca-Beaufortoorgang in die Noordoostelike gedeelte van die hoof Karookom.

- Muntingh, Dirk Jacobus

Authors: Muntingh, Dirk Jacobus
Date: 2014-03-27
Subjects: Sedimentology , Geology - Cape Province - Karoo Basin. , Geology, Stratigraphic
Type: Thesis
Identifier: uj:4528 , http://hdl.handle.net/10210/9865
Description: M.Sc. (Geology) , The study was undertaken to investigate the stratigraphic and sedimentological character of the transition between the Ecca and Beaufort Groups in the northeastern region of the main Karoo basin. Detailed stratigraphic profiles demonstrate that the transition comprises a regressional sequence of dark basinal shale overlain by sandy delta-lobe deposits. This is overlain by lenticular sandstones and shale representing meandering stream deposits. The deltaic sedimentary rocks vary markedly along strike and record deposition in four different deltaic sUbenvironments, namely: (A) "Normal" central delta lobe areas characterized by distal mouth bar sandstone-shale rhythmites gradationally overlain by proximal distributary mouth bar sandstones. (B) Interdistributary bay areas characterized by stacked thin upward-coarsening shale-sandstone cycles. (C) Areas of strong distributary channel erosion where prodelta shale deposits are erosively overlain by distributary or fluvial channel sandstones. No distributary mouth bar deposits are present. (D) Storm-dominated areas comprising prodelta sedimentary rocks which are in turn overlain by storm and possible barrier sand deposits. Palaeocurrent directions indicate that sediment transport was from the north-west, north and north-east. The concentrations of the trace elements B, V, Zn and Ni in prodelta shales indicate the possible prevalence of both marine and freshwater conditions in the near-coastal waters of the Ecca basin. Lateral variation of depositional environments on the same stratigraphic level makes the placing of the Ecca-Beaufort contact based on genetic criteria unsuitable. It is therefore suggested that purely lithostratigraphic criteria be used. On this basis the Ecca-Beaufort contact is taken at the base of the first prominent sandstone which overlies the Volksrust Shale Formation.
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Die geologie van die Sishen-ysterertsmyn

- Van Schalkwyk, John Francois

Authors: Van Schalkwyk, John Francois
Date: 2014-03-10
Subjects: Geology - South Africa - Sishen , Iron ores - South Africa - Sishen
Type: Thesis
Identifier: uj:4239 , http://hdl.handle.net/10210/9598
Description: M.Sc. (Geology) , The Sishen Iron Ore Mine is situated in the Northern Cape Province at the northern extremity of the Maremane dome. The stratigraphy of the Sishen Iron Ore Mine consist of carbonate rocks of the Campbellrand Subgroup which are unconformably overlain by the Wolhaarkop Breccia. The Wolhaarkop Breccia grades upwards through a shaly unit into an succession of iron formation known as the Manganore Iron Formation. The positive correlation of the Manganore Iron Formation with the Asbesheuwels Subgroup, of which it represents the oxidized equivalent, assigns a collapse origin to the Wolhaarkop Breccia. The siliciclastic Gamagara Formation overlies the Manganore Iron Formation unconformably. The unconformity cuts through the Manganore stratigraphy into the carbonate rocks of the Campbellrand Subgroup. The Gamagara Formation consist of a basal unit of conglomerates and argillite of varying thickness in the form of stacked upward fining alluvial cycles. These are overlain by two well 'developed upward coarsening progradational shale to quartzite deltaic cycles. A massive argillite unit marks the upper contact of the Gamagara Formation with the overlying Makganyene and Ongeluk Formations. This unit represents a milonite along a thrust plane and the Ongeluk lava and parts of the Makganyene diamictite were thrusted over the Gamagara Formation which is a correlative of the Mapedi Formation of the 01ifantshoek Group...
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Petrography and geochemistry of the Hotazel Formation on Mukulu 265, Kalahari Manganese Field, Northern Cape Province

- Vafeas, Nicholas Andrew

Authors: Vafeas, Nicholas Andrew
Date: 2016
Subjects: Geology - South Africa - Northern Cape , Manganese ores - Kalahari Desert , Iron ores
Language: English
Type: Masters (Thesis)
Identifier: http://hdl.handle.net/10210/124793 , uj:20960
Description: Abstract: With the need for steel ever increasing, the Kalahari Manganese Deposit is a resource of great economic importance and as such, the need for accurate data and comprehensive studies on the manganese and iron ores are vital. The Mukulu 265 project area is positioned along the border of the high (Wessels-type) to low (Mamatwan-type) grade manganese ore and like the neighbouring N’chwaning and Wessels mines, is subject to: intrusions by diabase dykes; thrusting and subsequent overlapping of strata; normal faulting and associated Wessels event enrichment; and erosion along two separate unconformities, namely the Mapedi/Gamagara and the Kalahari unconformities. As a result of these structural evolutionary events, both the iron and the manganese ores vary in grade, mineralogy and texture from north to south and east to west. This variation is the result of contact metamorphism and associated igneousrelated hydrothermal fluids; supergene alteration along the Mapedi/Gamagara unconformity; and metasomatic alteration along the reactivated north-south striking normal faults. The latter is responsible for the systematic residual enrichment in manganese content and the increase in high-grade minerals in the manganese ore, as well as the subsequent leaching of carbonates and silicates that is witnessed in the northern section of Mukulu 265. Based on varying degrees of alteration from south to north on Mukulu 265, the banded iron formation, hematite lutite and manganese ores have been broadly categorised into three classes, namely least altered (LA), partially altered (PA) and highly altered (HA). The LA rock-types are considered to be closest to the primary rock-types found on Mukulu 265 and show relatively little alteration compared to the PA and HA samples. From the LA to the HA manganese ore samples, there is a clear increase in manganese oxides such as hausmannite, predominantly at the expense of carbonates such and kutnohorite and dolomite, particularly within the ovoids. Sampling and analysing the manganese ore by visually distinguishing common subzones, reveals a distinct pattern within the lower manganese ore beds of the selected boreholes that shows a lateral geochemical trend. This geochemical trend exhibits higher concentrations in manganese with lower concentrations in undesired elements such as iron within the lowercentral portion of the lower manganese ore bed. The geochemical pattern exhibited by the ore zones forms the basis by which the ore grade changes with depth and thus underpins its importance for selective mining processes. An interpretation of the ore genesis based on geochemical and mineralogical results for the lower manganese ore bed, suggests that the... , M.Sc. (Geology)
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Provenance and age of Paleoproterozoic red beds of the Elim Group (Griqualand West, South Africa) as determined from detrital zircon age populations

- Dreyer, Daphne

Authors: Dreyer, Daphne
Date: 2014
Subjects: Geology, Stratigraphic , Paleontology, Proterozoic , Geology - South Africa - Griqualand West , Paleontology - South Africa - Griqualand West
Language: English
Type: Masters (Thesis)
Identifier: http://hdl.handle.net/10210/84446 , uj:19221
Description: Abstract: The Gamagara/Mapedi and Lucknow Formations of the Elim Group, along with the Olifantshoek Group, within the Paleoproterozoic Keis Supergroup, are very important stratigraphic units. Their economic importance is due to the presence of the oldest known red bed successions which hosts well preserved lateritic soil profiles, as well as the ancient supergene high-grade laminated iron ores of the Sishen-Postmasburg area on the Maremane dome. These high-grade iron ore deposits are associated with the pre-ElimlGamagara unconformity, which is located at the base of the conglomerate unit of the GamagaralMapedi Formation known as the Doornfontein Member. The main focus of the study i3 on the lateral correlation of the Elim Group in the Griqualand West area to geology in the Highveld region of South Africa, with specific focus on the depositional age of the Elim Group, i.e. the Gamagara/Mapedi and Lucknow Formations. The depositional age, as well as the lateral correlation of the Elim Group, has however remained a matter of contention, and this succession has previously been correlated with the Dwaalheuwel- Magaliesberg succession of the upper Pretoria Group of the Transvaal Supergroup, and more recently correlated to the Swaershoek- and Alma Formations of the lower Waterberg Group. The correlation of the Elim Group to geology in the Highveld region of South Africa area is however problematic as there is stratigraphic duplication of the red beds in the Elim and Olifantshoek Groups, as well as strata from the Transvaal Supergroup within the Griqualand West area, caused by intense folding and faulting. A higher degree of certainty, regarding the age constraints of the Elim Group, and more specifically the Doornfontein Member of the Gamagara/Mapedi Formation, is thus required to assist with a re-evaluation of the lateral extent and depositional age of the high-grade iron ore deposits in the Highveld area as well as its correlation to geological successions elsewhere in South Africa. The age constraints for the GamagaralMapedi and the lower Lucknow Formations were obtained from U-Pb geochronological studies of detrital zircon populations that were extracted from various samples from the Gamagara/Mapedi and lower Lucknow Formations. The detrital zircon grains were analysed by means of Laser Ablation Inductively Coupled Mass Spectrometry (LAICP- MS) at the analytical facility Spectrum, at the University of Johannesburg... , M.A. (Geology)
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Paleomagnetism and geochemistry of the Mesoarchean Klipwal diamictite, Mozaan Group, Pongola Supergroup, South Africa

- Lechekoane, Tshepang

Authors: Lechekoane, Tshepang
Date: 2016
Subjects: Pongola Supergroup (South Africa) , Paleomagnetism - South Africa - Pongola Supergroup , Geochemistry - South Africa - Pongola Supergroup , Conglomerate - South Africa - Pongola Supergroup , Geology, Stratigraphic, Archaean
Language: English
Type: Masters (Thesis)
Identifier: http://hdl.handle.net/10210/235930 , uj:24137
Description: M.Sc. (Geology) , Abstract: The Mozaan Group of the Pongola Supergroup together with the correlative Witwatersrand Supergroup host the oldest, best-preserved cover successions deposited on a stable craton between 2.96 – 2.84 Ga ago. Little is known about the tectonic processes which operated on the young Earth in the Archean. Paleomagnetism remains the most robust method with which early cratonic movements can be constrained. There is a poor paleomagnetic record for the Kaapvaaal Craton during the Archean. This study aims to contribute to the pole density and constrain the apparent polar wander path (APWP) for the Kaapvaal Craton during this period, as well as to interrogate the sediment source of the Klipwal Member diamictite. The provenance of Klipwal diamictite was previously poorly understood. This study contributes new insight as to the origin of the sediments making up this unit. The geochemical data suggests a strong mafic to ultramafic source with minor felsic input. The CIA is consistent with moderate weathering which probably took place at the source. The elevated levels of iron are attributed to the precipitation of ferric-oxyhydroxides from the anoxic seawater with a high concentration of dissolved iron. Petrographic and field studies suggest that sediments were sourced from an off craton greenstone terrane adjacent to the Witwatersrand – Mozaan basin indicating that the extent of glaciation was more extensive than previously thought. A glacial influence is envisioned but more reliable data is required. During thermal demagnetisation, a low temperature (250 - 350°C), steep northerly negatively inclined component HIG was observed. Because of the negative bootstrap fold test, this component has been interpreted to be an overprint. A total of six sites were sampled but only five produced meaningful results. Sites KWU, KWV, KWW, KWX and KWZ show no preferred grouping which impedes the calculation of a reliable pole. Individual VGPs were calculated for these sites to reveal three groups when plotted together with Meso – Neoarchean poles. Sites KWX, KWZ and other previously proposed poles for the Klipwal diamictite record an overprint around 2.8 - 2.7 Ga This overprint is associated with post-Pongola granites which intruded the Pongola Supergroup during this interval. Another group is observed around 1.05 Ga as recorded by sites KWU and KWV. This event is interpreted as an overprint associated with the Namaqua-Natal orogeny which affected the eastern margin of the Kaapvaal Craton during this time. All the sites were ultimately combined to calculate an average pole situated at longitude = -40.3° and latitude 69.1° with α95 = 12 presented in this study. This new pole together with those previously proposed demonstrates that a reliable APWP for the Kaapvaal Craton during the Archean remains elusive.
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Die strategrafie an sedimentologie van die chuniespoort-groep in Noordwes-Transvaal

- Fourie, Edward Thornton

Authors: Fourie, Edward Thornton
Date: 1984
Subjects: Geology, Stratigraphic
Language: Afrikaans
Type: Masters Thesis
Identifier: http://hdl.handle.net/10210/22197 , uj:16173
Description: Abstract: The Chuniespoort Group was deposited between 2460 and 2224 m.y. ago and consists of a carbonate unit (the Malmani Subgroup, 1600-3600 m thick) conformably overlain by a banded iron-formation unit (the Penge Iron-formation, approximately 260 m thick). Stratigraphic profiles, measured in outcrop, were used to subdivide the unit into formations and members and to define sedimentary lithofacies and lithofacies cycles. The process-response model was then applied to the lithofacies, lithofacies associations and sedimentary cycles to determine their origin, environment of deposition and diagenetic history... , M.Sc. (Geology)
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A comparison between detrital zircon age populations of the Koegas Subgroup of the Ghaap Group and overlying Makganyene Diamictite of the Postmasburg Group, Transvaal Supergroup, Griqualand West Area

- Ngobeli, Rebeun

Authors: Ngobeli, Rebeun
Date: 2019
Subjects: Transvaal Supergroup (South Africa) , Geology, Stratigraphic
Language: English
Type: Masters (Thesis)
Identifier: http://hdl.handle.net/10210/418439 , uj:35478
Description: Abstract: The Transvaal Supergroup of southern Africa on the Kaapvaal Craton holds some of the most important geological successions in the world and has preserved exciting geological events of the late Archean to Early Paleoproterozoic (i.e. Snowball Earth- and Great Oxidation Events and the world renowened Kalahari Manganese Field). In South Africa, the supergroup is subdivided into Griqualand West- and Transvaal outcrop areas which are further subdivided into Ghaap-, Postmasburg-, Chuiniespoort- and Pretoria Groups respectively. The Makganyene Diamictite at base of the Postmasburg Group of the Transvaal Supergroup in Griqualand West overlies strata of the Koegas- and Asbesheuwels Subgroups of the Ghaap Group with a marked low-angle erosional unconformity but is in conformable contact with the overlying Ongeluk Lava. .. , M.Sc. (Geology)
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