Showing items 1 - 15 of 15

Your selections:

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

  • 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)
  • Full Text:

Die geologie van die Krokodilrivierfragment, Transvaal

Die mineralogie en geochemie van sedimentêre siklusse in die Kuruman- en Griquatown-ysterformasies van die Transvaal-Supergroep in Griekwaland-Wes

Die sedimentologie en stratigrafie van die Ecca-Beaufortoorgang in die Noordoostelike gedeelte van die hoof Karookom.

  • 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.
  • Full Text:

Die strategrafie an sedimentologie van die chuniespoort-groep in Noordwes-Transvaal

  • 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)
  • Full Text:

Genetiese stratigrafie en sedimentologie van die opeenvolging Karoo in die westelike en noordelike deel van die Waterbergsteenkoolveld

Provenance and age of Paleoproterozoic red beds of the Elim Group (Griqualand West, South Africa) as determined from detrital zircon age populations

  • 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)
  • Full Text:

The geological evolution of Neumayerskarvet in the Northern Kirwanveggen, Western Dronning Maud Land, Antartica

  • Authors: Harris, Philip David
  • Date: 2012-08-15
  • Subjects: Geology - Antarctica - Kirwanveggen , Geology, Stratigraphic , Gneiss - Antarctica - Kirwanveggen
  • Type: Thesis
  • Identifier: uj:9434 , http://hdl.handle.net/10210/5867
  • Description: D.Sc , Neumayerskarvet forms a continuous outcrop of high-grade gneiss within the northern Kirwanveggen in western Dronning Maud Land, Antarctica. A detailed geological study was carried out to obtain an evolutionary history for Neumayerskarvet. The work involved field mapping to provide a structural framework for further metamorphic and isotopic investigations. U-Pb zircon SHRIMP analysis, Rb-Sr, Sm-Nd and Ar-Ar mineral analysis were used to provide absolute time constraints on different tectono-metamorphic periods and cooling histories. Petrographic investigations, coupled with mineral chemistry on kyanite-bearing leucogneisses, provided information on the P-T conditions. An understanding of the crustal evolution of the high-grade gneisses was obtained through whole-rock geochemistry and isotope analysis. The dominant lithotectonic unit preserved at Neumayerskarvet is biotite-garnet migmatite gneiss, which is inter-fingered with quartzofeldspathic gneisses and banded quartz-feldspar gneisses. Several magmatic phases have intruded these sequences. Three tectonometamorphic cycles have been established for the region. The first two cycles are assigned to a period between 1390 Ma and 970 Ma while the third cycle is constrained between 650 Ma and 450 Ma. An age of ca. 1390 Ma for the biotite-gamet migmatite gneiss provides a maximum age for the first tectono-metamorphic cycle. Zircon growth and magmatism during this tectonometamorphic cycle constrains deformation (D1a) between ca. 1160 Ma and ca. 1110 Ma. Deformation is marked by the development of a penetrative planar foliation and isoclinal recumbent folding. High-pressure metamorphic conditions during this cycle have been suggested from previous investigations but are not confirmed in this investigation as the kyanite-bearing leucogneisses intruded during the second tectono-metamorphic cycle. It is possible that the first and second tectono-metamorphic cycles are part of a progressive deformational cycle. The second tectono-thermal cycle represents a major period of magmatism and tectonism constrained between ca. 1110 Ma and ca. 970 Ma. Major folding occurred during this tectonic episode, represented by isoclinal recumbent folds, sheath folds and re-folded fold interference patterns (D1b). The structural fabric elements produced a complicated relationship of transposed coplanar and colinear composite fabrics. Fabric geometries suggest NNW-SSE tectonic transport directions. Garnet-kyanite-muscovite-biotite-quartz assemblages (Mn+1 (nkv)) provide P-T estimates of 710-760 °C and 7.8-8.5 kb. Later metamorphic assemblages of sillimanite-muscovite-high Ca-garnet-biotite-quartz (Mn+2 (nkv)) provide P-T estimates of 630- 690 °C and 6.0-7.4 kb. The whole-rock isotope data indicate that material accreted during the second tectono-metamorphic cycle experienced a short crustal residence time. The third tectono-metamorphic cycle is constrained by isotopic ages between 650 Ma and 450 Ma. Deformation (D2) that re-works earlier tectonic fabrics may represent signatures of this cycle, but the exact nature of the deformation remains enigmatic. Tectonic fabric styles and geometries are similar to the more dominant D1 tectonic episode, making recognition of temporal relationships difficult. Diffusional P-T data from garnet-biotite rims (Mn+3 (nkv)) provide P-T cooling estimates of 560-570 °C and 4.4-4.6 kb. Re-working of the high-grade gneisses during the third tectono-metamorphic cycle, with no addition or accretion of new crustal material is indicated by the isotopic data. A final tectonic episode (D3) comprising late brittle deformation and uplift is equated to Gondwana break-up.
  • Full Text:

The nature and origin of the polymetallic Salt River massive sulfide deposit, Northern Cape Province, South Africa

  • Authors: Osburn, Keith Craig
  • Date: 2012-06-07
  • Subjects: Namaqua Metamorphic Province , Sedimentation and deposition , Geology (Kakamas, South Africa) , Salt River sulfide deposit , Petrology , Metamorphic rocks , Geology, Stratigraphic
  • Type: Thesis
  • Identifier: uj:8667 , http://hdl.handle.net/10210/5022
  • Description: M.Sc. , The Salt River deposit is a poly-metallic base metal deposit with a Zn-Cu-Pb metal content that occurs southwest of the town of Kakamas within the Northern Cape Province, South Africa. The Salt River deposit occurs within the Geelvloer Formation of the Bushmanland Subprovince of the Proterozoic Namaqua Metamorphic Province (NMP). This study constitutes the first detailed study of the host rock succession to the Salt River deposit, by investigating the lithostratigraphy, petrography geochemistry and geochronology. During the course of the study, various styles of wall-rock alteration were identified and investigated to determine their effect on the host rock succession. A further aim of this study was to classify the Salt River deposit and compare it to neighboring deposits occurring in the NMP. Geochronological studies were undertaken to define the age of mineralization. Detailed logging of exploration diamond drill core combined with petrographic investigation was used to define thirteen distinct lithotypes. The stratigraphy is dominated by felsic grey gneisses and mafic amphibolites, minor calc-silicate rocks, granitic augen gneisses, pegmatites and two lithologies that represent the metamorphosed equivalents of hydrothermally-altered host rock. Lithostratigraphic investigations yielded a rather uniform succession containing four distinct marker beds defined by their common occurrence and ease of correlation across various boreholes.
  • Full Text:

The petrology, petrography and geochemistry of anomalous borehole core sequences in the Highveld coalfield, South Africa : a case study for diatreme activity

  • Authors: Van der Walt, Byron
  • Date: 2012-11-12
  • Subjects: Petrology - South Africa - Highveld Region , Borings - South Africa - Highveld Region , Breccia - South Africa - Highveld Region , Diatremes - South Africa - Highveld Region , Geology, Stratigraphic
  • Type: Thesis
  • Identifier: uj:7380 , http://hdl.handle.net/10210/8169
  • Description: M.Sc. (Geology) , Three anomalous borehole core sequences from the north eastern Karoo Basin are examined. The boreholes are located up to 30 km from each other and are lithostratigraphically completely atypical for the Vryheid Formation, Ecca Group, Karoo Supergroup. The lithologies of the three boreholes are intensely brecciated for the most part, while all of the surrounding boreholes reveal normal stratigraphy; their sedimentary strata are normally horizontal with no faulting present. The only known disturbances to the Vryheid Formation in the study area are the occurrence of intrusive mafic dolerite sills and dykes, which are known to have been contemporaneous with and immediately following the eruption of the Drakensburg Group basaltic lavas. The borehole core lithologies are described in detail with reference to their textural, mineralogical and petrographic characteristics. Mineral and bulk rock chemical data are presented. Several modes of origin of the brecciated core sequences are considered, with the primary hypothesis that the brecciation is due to diatreme activity. A review of diatremes and their mode of emplacement is proposed with reference to their occurrence within the Karoo Igneous Province, as some diatremes in the Karoo are associated with dolerite sill emplacement. The isolated occurrences, lithologies, petrography, alteration and geochemistry of the sequences are used to argue that the Vryheid Formation, intersected in the form of the three anomalous boreholes, was disturbed by diatreme activity, which are genetically related to the late dolerite sill emplacement into the Karoo Supergroup rocks.
  • Full Text:

The provenance of the Buffels River Complex : the timing of its formation and the possible source area of its diamonds

  • Authors: Terblanche, Sullivan
  • Date: 2017
  • Subjects: Diamond deposits - South Africa - Northern Cape , Geology, Stratigraphic , Complexes (Stratigraphy) - South Africa - Northern Cape , Buffels River Complex (South Africa)
  • Language: English
  • Type: Masters (Thesis)
  • Identifier: http://hdl.handle.net/10210/285275 , uj:30842
  • Description: Abstract: The Buffels River Complex is located in the Northern Cape Province between the towns of Springbok and Kleinzee. Mining of the diamondiferous gravels of the Buffels River Complex have taken place over the last 50 years. During this time very little scientific work has been conducted on the deposit, except for an internal unpublished report by Myburgh (2004) for De Beers. The age of deposition as well as the source regions of the diamonds are unknown. Understanding the age of deposition of the sediments of the Buffels River Complex as well as the source regions will give insight into the development of the coastal hinterlands after the breakup of Gondwana. Using the current understanding of the landscape evolution after the breakup of Gondwana and comparing it to the Buffels River Complex, a better understanding of the deposit can be made. Attaining the objectives above required field work of the Buffels River complex, U/Pb detrital zircon provenance studies on the different sedimentary units of the BRC as well as 40Ar - 39Ar age determination of Mnoxyhydroxide crusts. Field work on the Buffels River Complex, relating the erosional surfaces and accompanying stratigraphy with that of the known landscape evolution, focusing on the formation of the landsurfaces after the breakup of Gondwana indicated that the Buffels River Complex did indeed form after the breakup of Gondwana. This was based on similarities between the paleoenvironments as well as the depositional environments during the formation of the Post African 1-and Post African 2 landsurfaces and the sediments of the Buffels River Complex. 40Ar – 39Ar age determination of the Mn-oxyhydroxide crusts related to the formation of the erosional surfaces found in the stratigraphy of the Buffels River Complex were unsuccessful, producing only near plateaus and staircase patterns. These patterns indicated that multiple K-bearing phases are present in the samples. The release patterns produced very old ages ranging from early Cambrian to late Silurian. This indicates that the ages obtained most likely where produced from K–baring detrital mineral phases present in the Mn-oxyhydroxide crusts and not related to the formation of the Mnoxyhydroxide crusts. U/Pb provenance studies of the detrital zircon grains obtained from the different units of the Buffels River Complex produced a wide range of detrital zircon ages ranging from Archean to Cambrian. The absence of younger ages which is observed within the Karoo Supergroup indicates that the Buffels River Complex must have formed from a restricted source area which did not contain any Karoo Supergroup rocks. , M.Sc. (Geology)
  • Full Text:

The sedimentology and economic potential of the auriferous Middelvlei Reef on Driefontein Consolidated Limited

The stratigraphy, sedimentology and petrography of the number 2 coal seam in the northern portion of the Permian Highveld Coalfield, Karoo Basin, South Africa

  • Authors: Francis, Fabian Anthony
  • Date: 2019
  • Subjects: Geology, Stratigraphic , Coal - Geology - South Africa , Sedimentation and deposition - South Africa
  • Language: English
  • Type: Masters (Thesis)
  • Identifier: http://hdl.handle.net/10210/417413 , uj:35349
  • Description: Abstract: This study focusses on the stratigraphy, sedimentology and petrography of the No. 2 depositional sequence in the northern portion of the Permian Highveld Coalfield, Karoo Basin, South Africa. A database comprising 7 000 vertical boreholes was utilised to create series of elevation, thickness, quality and petrographic distributions (called grids) across a 4 500 km2 study area. The primary aim of this study is to develop a palaeoenvironmental and depositional model for the No. 2 depositional sequence, from the base of the Dwyka Group up to the top of the No. 2 Coal Seam (C2 Seam). This study provides a sub-regional database of the C2 Seam, its physical attributes (proximate analyses), general petrographic composition and overall distribution of the coal relative to its interpreted depositional environment, should this seam ever be mined. An investigation of this scale has never been done before in the Highveld Coalfield... , M.Sc. (Geology)
  • Full Text:

The structure, stratigraphy and sedimentology of the Black Reef-Malmani-Rooihoogte succession of the Transvaal supergroup south-west of Pretoria

Vapour-absent melting in metapelite during the 2700 Ma Limpopo metamorphic event in South Africa : further evidence of the granite-granulite link

  • 1
  • Disclaimer
  • Privacy
  • Copyright
  • Contact