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Academic literature on the topic 'Kaapvaal'

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Published: 10 December 2022
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Journal articles on the topic "Kaapvaal"

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de Wit, M. J. "Kaapvaal Craton special volume- An introduction." South African Journal of Geology 107, no. 1-2 (June 1, 2004): 1–6. http://dx.doi.org/10.2113/107.1-2.1.

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2

Herzberg, Claude T. "Lithosphere peridotites of the Kaapvaal craton." Earth and Planetary Science Letters 120, no. 1-2 (November 1993): 13–29. http://dx.doi.org/10.1016/0012-821x(93)90020-a.

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Baptiste, V., and A. Tommasi. "Petrophysical constraints on the seismic properties of the Kaapvaal craton mantle root." Solid Earth Discussions 5, no. 2 (July 16, 2013): 963–1005. http://dx.doi.org/10.5194/sed-5-963-2013.

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Abstract. We calculated the seismic properties of 47 mantle xenoliths from 9 kimberlitic pipes in the Kaapvaal craton based on their modal composition, the crystal preferred orientations (CPO) of olivine, ortho- and clinopyroxene, and garnet, the Fe content of olivine, and the pressures and temperatures at which the rocks were equilibrated. These data allow constraining the variation of seismic anisotropy and velocities with depth. The fastest P wave and fast split shear wave (S1) polarization direction is always close to olivine [100] maximum. Changes in olivine CPO symmetry result in minor variations in the seismic anisotropy patterns. Seismic anisotropy is higher for high olivine contents and stronger CPO. Maximum P waves azimuthal anisotropy (AVp) ranges between 2.5 and 10.2% and S waves polarization anisotropy (AVs) between 2.7 and 8%. Seismic properties averaged in 20 km thick intervals depth are, however, very homogeneous. Based on these data, we predict the anisotropy that would be measured by SKS, Rayleigh (SV) and Love (SH) waves for 5 end-member orientations of the foliation and lineation. Comparison to seismic anisotropy data in the Kaapvaal shows that the coherent fast directions, but low delay times imaged by SKS studies and the low azimuthal anisotropy and SH faster than SV measured using surface waves may only be consistently explained by dipping foliations and lineations. The strong compositional heterogeneity of the Kaapvaal peridotite xenoliths results in up to 3% variation in density and in up to 2.3% of variation Vp, Vs and the Vp/Vs ratio. Fe depletion by melt extraction increases Vp and Vs, but decreases the Vp/Vs ratio and density. Orthopyroxene enrichment decreases the density and Vp, but increases Vs, strongly reducing the Vp/Vs ratio. Garnet enrichment increases the density, and in a lesser manner Vp and the Vp/Vs ratio, but it has little to no effect on Vs. These compositionally-induced variations are slightly higher than the velocity perturbations imaged by body-wave tomography, but cannot explain the strong velocity anomalies reported by surface wave studies. Comparison of density and seismic velocity profiles calculated using the xenoliths' compositions and equilibrium conditions to seismological data in the Kaapvaal highlights that: (i) the thickness of the craton is underestimated in some seismic studies and reaches at least 180 km, (ii) the deep sheared peridotites represent very local modifications caused and oversampled by kimberlites, and (iii) seismological models probably underestimate the compositional heterogeneity in the Kaapvaal mantle root, which occurs at a scale much smaller than the one that may be sampled seismologically.
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Rasmussen, Birger, Jian-Wei Zi, and Janet R. Muhling. "U-Pb evidence for a 2.15 Ga orogenic event in the Archean Kaapvaal (South Africa) and Pilbara (Western Australia) cratons." Geology 47, no. 12 (October 2, 2019): 1131–35. http://dx.doi.org/10.1130/g46366.1.

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Abstract There is geological evidence for widespread deformation in the Kaapvaal craton, South Africa, between 2.2 and 2.0 Ga. In Griqualand West, post-Ongeluk Formation (ca. 2.42 Ga) and pre-Mapedi Formation (>1.91 Ga) folding, faulting, and uplift have been linked to the development of a regional-scale unconformity, weathering horizons, and extensive Fe-oxide mineralization. However, the lack of deformational fabrics and the low metamorphic temperatures (<300 °C) have hampered efforts to date this event. Here we show that metamorphic monazite in Neoarchean shales from four stratigraphic intervals from the Griqualand West region grew at ca. 2.15 Ga, >400 m.y. after deposition. Combined with previous studies, our results show that sedimentary successions across the Kaapvaal craton deposited before ca. 2.26 Ga record evidence for crustal fluid flow at ca. 2.15 Ga, which is locally associated with thrust faulting, folding, and cleavage development. The style of the deformation is similar to that of the Ophthalmian orogeny in the Pilbara craton, Australia, which is interpreted to reflect the northeast-directed movement of a fold-thrust belt between 2.22 and 2.15 Ga. Our results suggest that the Kaapvaal and Pilbara cratons, which some paleogeographic reconstructions place together as the continent Vaalbara, experienced an episode of synchronous folding and thrusting at ca. 2.15 Ga. Deformation was followed by uplift and the development of unconformities that are associated with some of Earth’s oldest oxidative weathering and with the onset of Fe-oxide mineralization.
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Vinnik, L. P., R. W. E. Green, L. O. Nicolaysen, G. L. Kosarev, and N. V. Petersen. "Deep seismic structure of the Kaapvaal craton." Tectonophysics 262, no. 1-4 (September 1996): 67–75. http://dx.doi.org/10.1016/0040-1951(96)00012-1.

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Rollinson, H. R. "A terrane interpretation of the Archaean Limpopo Belt." Geological Magazine 130, no. 6 (November 1993): 755–65. http://dx.doi.org/10.1017/s001675680002313x.

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AbstractThe Limpopo Belt is a zone of thickened Archaean crust whose origin is currently explained by a late Archaean continent-continent collision between the Kaapvaal and Zimbabwe cratons. This review shows that the two cratons have fundamentally different geological histories and that the Zimbabwe Craton was unlikely to have behaved as a stable ‘cratonic’ block at the time of the Limpopo Belt collision. The geological histories of the Zimbabwe Craton, the North Marginal, Central and South Marginal zones of the Limpopo Belt and the Kaapvaal Craton are shown to be sufficiently different from one another to warrant their consideration as discrete terranes. The boundaries between the five units outlined above are all major shear zones, further supporting a terrane model for the Limpopo Belt. The five units were all intruded by late- to syn-tectonic granites c.2.6 Ga, constraining the accretion event to c. 2.6 Ga.
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Baptiste, V., and A. Tommasi. "Petrophysical constraints on the seismic properties of the Kaapvaal craton mantle root." Solid Earth 5, no. 1 (January 29, 2014): 45–63. http://dx.doi.org/10.5194/se-5-45-2014.

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Abstract. We calculated the seismic properties of 47 mantle xenoliths from 9 kimberlitic pipes in the Kaapvaal craton based on their modal composition, the crystal-preferred orientations (CPO) of olivine, ortho- and clinopyroxene, and garnet, the Fe content of olivine, and the pressures and temperatures at which the rocks were equilibrated. These data allow constraining the variation of seismic anisotropy and velocities within the cratonic mantle. The fastest P and S2 wave propagation directions and the polarization of fast split shear waves (S1) are always subparallel to olivine [100] axes of maximum concentration, which marks the lineation (fossil flow direction). Seismic anisotropy is higher for high olivine contents and stronger CPO. Maximum P wave azimuthal anisotropy (AVp) ranges between 2.5 and 10.2% and the maximum S wave polarization anisotropy (AVs), between 2.7 and 8%. Changes in olivine CPO symmetry result in minor variations in the seismic anisotropy patterns, mainly in the apparent isotropy directions for shear wave splitting. Seismic properties averaged over 20 km-thick depth sections are, therefore, very homogeneous. Based on these data, we predict the anisotropy that would be measured by SKS, Rayleigh (SV) and Love (SH) waves for five endmember orientations of the foliation and lineation. Comparison to seismic anisotropy data from the Kaapvaal shows that the coherent fast directions, but low delay times imaged by SKS studies, and the low azimuthal anisotropy with with the horizontally polarized S waves (SH) faster than the vertically polarized S wave (SV) measured using surface waves are best explained by homogeneously dipping (45°) foliations and lineations in the cratonic mantle lithosphere. Laterally or vertically varying foliation and lineation orientations with a dominantly NW–SE trend might also explain the low measured anisotropies, but this model should also result in backazimuthal variability of the SKS splitting data, not reported in the seismological data. The strong compositional heterogeneity of the Kaapvaal peridotite xenoliths results in up to 3% variation in density and in up to 2.3% variation of Vp, Vs, and Vp / Vs ratio. Fe depletion by melt extraction increases Vp and Vs, but decreases the Vp / Vs ratio and density. Orthopyroxene enrichment due to metasomatism decreases the density and Vp, strongly reducing the Vp / Vs ratio. Garnet enrichment, which was also attributed to metasomatism, increases the density, and in a lesser extent Vp and the Vp / Vs ratio. Comparison of density and seismic velocity profiles calculated using the xenoliths' compositions and equilibration conditions to seismological data in the Kaapvaal highlights that (i) the thickness of the craton is underestimated in some seismic studies and reaches at least 180 km, (ii) the deep sheared peridotites represent very local modifications caused and oversampled by kimberlites, and (iii) seismological models probably underestimate the compositional heterogeneity in the Kaapvaal mantle root, which occurs at a scale much smaller than the one that may be sampled seismologically.
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Hofmann, A., H. Xie, L. Saha, and C. Reinke. "Granitoids and greenstones of the White Mfolozi Inlier, south-east Kaapvaal Craton." South African Journal of Geology 123, no. 3 (September 1, 2020): 263–76. http://dx.doi.org/10.25131/sajg.123.0019.

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Abstract A Palaeoarchaean greenstone fragment and associated granitoid gneisses from an area south of Ulundi in KwaZulu-Natal is described. The fragment consists of an association of garnetiferous amphibolite and calc-silicate that was intruded at 3388 ± 4 Ma by tonalite and at 3275 ± 4 Ma by trondhjemite. Strong ductile deformation of the greenstones and granitoids under amphibolite facies conditions (7 kbar and 600 to 650°C) took place prior to uplift and emplacement of a granite batholith at ~3.25 Ga ago in which the granitoid gneiss-greenstone domain is now found. Magmatism 3.27 to 3.25 Ga ago was a direct response to regional metamorphism and anataxis, and gave rise to stabilization of the southeastern Kaapvaal Craton at that time, earlier than other parts of the craton. Deposition of quartz-arenites on stable granitic basement took place &lt;3.1 Ga ago. Contrasting ages in magmatic pulses and regional metamorphism reflect a different crustal growth history of the eastern and southeastern part of the Kaapvaal Craton.
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Jones, M. Q. W. "Heat flow in the Bushveld Complex, South Africa: implications for upper mantle structure." South African Journal of Geology 120, no. 3 (September 1, 2017): 351–70. http://dx.doi.org/10.25131/gssajg.120.3.351.

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Abstract Geothermal measurements in South Africa since 1939 have resulted in a good coverage of heat flow observations. The Archaean Kaapvaal Craton, in the central part of South Africa, is the best-studied tectonic domain, with nearly 150 heat flow measurements. The greatest density of heat flow sites is in the Witwatersrand Basin goldfields, where geothermal data are essential for determining refrigeration requirements of deep (up to 4 km) gold mines; the average heat flow is 51 ± 6mWm-2. The Bushveld Complex north of the Witwatersrand Basin is an extensive 2.06 Ga ultramafic-felsic intrusive complex that hosts the world’s largest reserves of platinum. The deepest platinum mines reach ~2 km and the need for thermal information for mine refrigeration engineering has led to the generation of a substantial geothermal database. Nearly 1000 thermal conductivity measurements have been made on rocks constituting the Bushveld Complex, and borehole temperature measurements have been made throughout the Complex. The temperature at maximum rock-breaking depth (~2.5 km) is 70°C, approximately 30°C higher than the temperature at equivalent depth in the Witwatersrand Basin; the thermal gradient in the Bushveld Complex is approximately double that in the Witwatersrand Basin. The main reason for this is the low thermal conductivity of rocks overlying platinum mines. The Bushveld data also resulted in 31 new estimates for the heat flux through the Earth’s crust. The overall average value for the Bushveld, 47 ± 7 mW m-2, is the same, to within statistical error, as the Witwatersrand Basin average. The heat flow for platinum mining areas (45 mW m-2) and the heat flux into the floor of the Witwatersrand Basin (43 mW m-2) are typical of Archaean cratons world-wide. The temperature structure of the Kaapvaal lithosphere calculated from the Witwatersrand geothermal data is essentially the same as that derived from thermobarometric studies of Cretaceous kimberlite xenoliths. Both lines of evidence lead to an estimated heat flux of ~17 mW m-2 for the mantle below the Kaapvaal Craton. The estimated thermal thickness of the Kaapvaal lithosphere (235 km) is similar to that defined on the basis of seismic tomography and magnetotelluric studies. The lithosphere below the Bushveld Complex is not significantly hotter than that below the Witwatersrand Basin. This favours a chemical origin rather than a thermal origin for the upper mantle anomaly below the Bushveld Complex that has been identified by seismic tomography studies and magnetotelluric soundings.
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Heaman, Larry M., and D. Graham Pearson. "Nature and evolution of the Slave Province subcontinental lithospheric mantleThis article is one of a series of papers published in this Special Issue on the theme Lithoprobe — parameters, processes, and the evolution of a continent." Canadian Journal of Earth Sciences 47, no. 4 (April 2010): 369–88. http://dx.doi.org/10.1139/e09-046.

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A review of the ages determined for mantle material (xenoliths and xenocrysts entrained in kimberlite) derived from the Slave Province continental lithospheric mantle (CLM) indicates that a portion of the central Slave lithosphere may be ancient (3.5–3.3 Ga) harzburgite, but the majority of this lithosphere is much younger (2.9–2.0 Ga). Relying on the most robust chronometers, the majority of Slave lithosphere peridotite formed in the Neoarchean (peak at 2.75 Ga), whereas the majority of eclogite formed in the Paleoproterozoic (2.2–2.0 Ga). The northern Slave lithosphere contains evidence of peridotite xenolith ages that young with depth. The Paleoproterozoic eclogites may have multiple origins including remnants of subducted oceanic crust and mafic–ultramafic magmas that crystallized at great depth (100–200 km). Re–Os studies of sulfide inclusions in diamond indicate that some diamonds currently mined are ancient (∼3.5 Ga), but many Slave diamonds could be considerably younger. Most eclogitic diamonds recovered from the Slave craton are interpreted to be related to the formation of Paleoproterozoic eclogite. There is abundant evidence for Mesoproterozoic modification of the Slave lithosphere (e.g., heating by magma emplacement at great depth and metasomatism) and possible new addition to the lithosphere at that time. The Canadian Slave and African Kaapvaal lithospheres have similar peaks in cratonic peridotite formation ages at about 2.8 Ga, indicating that a large portion of the CLM in these two cratons formed and stabilized in the Neoarchean. One difference is that the Slave peridotites are much less enriched in SiO2, possibly reflecting the more metasomatized nature of the Kaapvaal CLM. The dominance of Paleoproterozoic formation ages for Slave mantle eclogites contrasts with the dominance of Neoarchean formation ages for Kaapvaal mantle eclogites.
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Dissertations / Theses on the topic "Kaapvaal"

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Bekker, Andrey. "Chemostratigraphy of the Early Paleoproterozoic carbonate successions (Kaapvaal and Wyoming cratons)." Diss., Virginia Tech, 2001. http://hdl.handle.net/10919/28965.

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Evidence of three glaciations in Paleoproterozoic successions of North America and at least one on three other continents, suggests that these glaciations were of global extent. In common with the Neoproterozoic record, carbonates cap the glacials. However, the relationship between biogeochemical cycling of carbon and ice ages has not been fully appreciated. This research involved the sedimentology and isotope stratigraphy of carbonates and shales in Paleoproterozoic glacially-influenced successions of Wyoming and South Africa. Carbonates of the Vagner Formation cap the middle of three diamictites in the Snowy Pass Supergroup, Medicine Bow Mountains, WY. The Duitschland Formation occurs between two glacial horizons in South Africa. Limestones retain negative d13C values for over 60 m in the Vagner Formation, and for over 100 m in the lower part of the Duitschland Formation. Isotope compositions of TOC from the lower part of the Duitschland Formation reveal pronounced enrichment resulting in significantly lower fractionation between organic and inorganic carbon. This is similar to enrichment noted in Neoproterozoic cap carbonates. Combined with strongly positive carbon isotope compositions in upper Duitschland carbonates, the data from the Vagner Formation underscores strongly positive-to-negative carbon isotope trends bracketing Paleoproterozoic glaciations. These trends mimic those noted in Neoproterozoic glacial successions and possibly indicate a recurrence of global glaciations. The Slaughterhouse and Nash Fork formations significantly postdate the glacial epoch. Both the lower part of the Nash Fork Formation, Medicine Bow Mountains and the Slaughterhouse Formation, Sierra Madre contains carbonates with 13C-enrichment >+6⠰ and locally up to +28%, whereas carbonates higher in the Nash Fork Formation have d13C values between 0 and 2.5%. This dramatic change in the composition of the Paleoproterozoic ocean is constrained at ca. 2.1 Ga (Karhu, 1993). Carbonates in the Rawhide Canyon section of the Whalen Group in the Hartville Uplift (the easternmost exposure of the Wyoming Craton) display δ13C values up to +8.2% suggesting correlation with the Slaughterhouse and Nash Fork formations and their deposition on continuous carbonate platform along the margin of the Wyoming Craton. These data support an open-marine, and therefore a global origin for the ca. 2.2-2.1 Ga carbon isotope excursion.
Ph. D.
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Larson, Angela Marie. "S-wave velocity structure beneath the Kaapvaal Craton from surface-wave inversions compared with estimates from mantle xenoliths." Thesis, Virginia Tech, 2004. http://hdl.handle.net/10919/34200.

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Results from two-station surface-wave inversions across the Archean Kaapvaal craton of southern Africa are compared with seismic velocities estimated from approximately 100 mantle xenoliths brought to the surface in kimberlite pipes. As the xenoliths represent a snapshot of the mantle at the time of their eruption, comparison with recently recorded seismic data provides an opportunity to compare and contrast the independently gained results. These cratonic xenoliths from the southern Kaapvaal, all less than 100Ma in age, have been analyzed geothermobarometrically to obtain the equilibrium P-T conditions of the cratonic mantle to about 180km depth [James et al 2004]. Seismic velocity-depth and density-depth profiles calculated on the basis of these P-T data and the mineral modes of the xenoliths are used to produce theoretical surface-wave dispersion curves and to generate roughly the upper 200km of a starting/reference model. A regionally-developed crustal structure [Niu and James 2002] was used for the crust and 300km of mantle values taken from PREM filled in down to 500km depth. This composite model was used as the starting/reference model for a Neighbourhood Algorithm surface-wave inversion using fundamental-mode Rayleigh-wave phase velocities for 16 paths within the Kaapvaal Craton from five events. The velocity structures found by that inversion are consistent with those derived from the xenolith data. Hence the velocity structure (i.e. thermal structure) of the mantle to a depth of 180km beneath the Kaapvaal craton is basically the same today as it was 80-90Ma. Further, synthetics runs show that for this surface-wave dataset, there is no strong low-velocity zone at depths shallower than at least 200km.
Master of Science
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Burger, Erasmus Petrus. "An Investigation of the carbonatites of the Kaapvaal Craton and their tectonic context." Diss., University of Pretoria, 2013. http://hdl.handle.net/2263/43297.

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Carbonatites are exotic rocks which usually occur in discrete intrusions. Considering the association of carbonatites with rifting environments, this dissertation proposes that: carbonatites occur in extensional tectonic settings and therefore carbonatite occurrence can be used to constrain an extensional setting for related occurrences. In order to give context in which to consider this hypothesis, the formation of carbonatites is reviewed. This work favours the direct mantle melting model as it is most relevant and consistent with observations of Kaapvaal Craton carbonatites. However the liquid immiscibility model cannot be entirely rejected with current knowledge. The hypothesis is applied to the Bushveld Igneous Complex after providing evidence of the rift-carbonatite association. The Bushveld Igneous Complex is considered to have been emplaced in the same tectonic setting as carbonatites. Therefore the Bushveld Igneous Complex was emplaced in an extensional tectonic setting. Finally the carbonatites which are part of the Pilanesberg Alkaline Province are considered in order to test the hypothesis. This work finds that the Pilanesberg carbonatites do occur with other rift related magmatism during the break-up of Nuna (Columbia) and therefore the hypothesis is not rejected. This work offers reviews of basic carbonatite background, formation models and carbonatite occurrences on the Kaapvaal Craton.
Dissertation (MSc)--University of Pretoria, 2013.
lk2014
Geology
MSc
Unrestricted
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Schoene, Robert Blair. "A thermotectonic framework for the growth and stabilization of the eastern Kaapvaal craton, southern Africa." Thesis, Massachusetts Institute of Technology, 2006. http://hdl.handle.net/1721.1/38251.

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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences, 2006.
Includes bibliographical references.
Continents are an amalgamation of crust and mantle lithosphere assembled over -4 Gyr and are therefore our best record of the early Earth. Exposures of rocks -3.0-3.7 Ga cover -20,000 km2 of eastern S. Africa and Swaziland, and provide a record of the continental assembly and subsequent stabilization of the eastern Kaapvaal craton. This thesis uses structural, geochronological, thermochronological and isotopic constraints to examine the tectonothermal processes responsible for the growth and stabilization of this portion of Mesoarchean lithosphere. Field mapping was focused on terrane-bounding shear zones and syntectonic plutons, and in combination with ID-TIMS U-Pb zircon geochronology and Sm-Nd analysis, places sub-Myr constraints on the timing, distribution, and kinematics of magmatism and deformation during growth and modification of continental lithosphere. Detailed U-Pb apatite and titanite thermochronological datasets are used in combination with finite difference numerical modeling to determine non-linear temperature-time paths for rocks between -650-300 °C from 3.45-3.08 Ga - providing a sensitive indicator of tectonic and magmatic processes in the middle to lower crust.
(cont.) From 3.2 to 3.3 Ga, multiple microcontinental fragments with distinct age and Nd isotopic characteristics were assembled along an oblique subduction zone boundary, with the Barberton Greenstone belt representing a lithospheric suture zone. During continental assembly and orogeny, strain was partitioned into 3236-3220 Ma syntectonic plutons and terrane-bounding transcurrent shear zones bordering the margins of the previously stabilized ca. 3.66-3.45 Ga Ancient Gneiss Complex. Subsequent 3.2-3.1 Ga reactivation of crustal anisotropies within the lithospheric suture zone - represented broadly by the Barberton Greenstone Belt - controlled the thermal and compositional reorganization of the crust through transtensional tectonics, exhumation of deep-crustal gneiss terranes, and upward migration of granitic batholiths. This final period of crustal modification was responsible for juxtaposing low-grade greenstone supracrustal rocks against middle- to lower-crustal gneiss terranes, and ultimately led to crustal stabilization in the greenstone belt and vicinity. These results support a model in which the stabilization of the Kaapvaal craton was a piece-wise transition resulting from lithospheric thickening and crustal thinning over, hundreds of Myr.
by Robert Blair Schoene.
Ph.D.
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Tinker, Justine. "Stratigraphic and structural interpretation of seismic reflection data across selected sections of the Kaapvaal Craton." Master's thesis, University of Cape Town, 2001. http://hdl.handle.net/11427/9739.

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Includes bibliography.
The Kaapvaal Craton is one of the best preserved of all Archean cratons. It is partially covered by the supracrustal sequences of the Witwatersrand, Ventersdorp and Transvaal Basin (and correlated Griqualand West Basin), which span almost a billion years (~3.1 to 2.2 Ga). This thesis describes and interprets eight newly available seismic reflection profiles, acquired by the vibroseis method to 6 seconds TWT, and totaling ~720 km in length. New stratigraphic and structural features are identified across three main regions: the Kaapvaal Craton's western margin, the northern margin or Bushveld lines (flanking the Thabazimbi-Murchison Lineament and across the western extremity of the Bushveld Igneous Complex) and the Kaapvaal Craton interior. The seismic data was interpreted using Charisma seismic interpretation software, Geoframe version 3.6 (developed by Geoquest, Schlumberger) on a UNIX, SUN workstation.
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Smildzins, V. (Viesturs). "Using mineral chemistry to constrain P-T conditions for mantle xenoliths from the Kaapvaal craton, South Africa." Master's thesis, University of Oulu, 2016. http://urn.fi/URN:NBN:fi:oulu-201611233107.

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Kimberlites are igneous rocks that originate by small degrees of melting of the mantle. Notably, kimberlites carry large variety of crustal and mantle xenoliths. Geochemical data on xenoliths can provide insights into the processes occurring in the subcontinental lithosphere (SCLM) and deeper. The Kaapvaal craton in South Africa hosts one of the best-studied kimberlite populations on Earth. In this thesis, a total of 24 thin sections of peridotite xenoliths from Group I Letlhakane, Letseng, Premier and Frank Smith kimberlites were investigated to constrain the pressure, temperature and depth of these mantle xenoliths. To do so, olivine, orthopyroxene, clinopyroxene, garnet and spinel were analyzed for their major element chemistry using electron microprobe analysis (EPMA). P-T calculations were performed using the PTEXL3 spreadsheet program, which contains different geothermobarometers. Depth constraints were fitted to the characteristic Kaapvaal craton geotherm. According to geochemical results and rough modal mineral estimations, the majority of the mantle xenoliths were identified as depleted harzburgites or lherzolites. Mineral major element compositions show trends of depletion, which correlate with the corresponding mantle xenolith sampling depth. Olivine and orthopyroxene have high average Mg# values of 92.1 and 93.0, respectively, at shallower depth ~70–160 Km. Below ~160 km, Mg# starts to drop rapidly and transition towards a more typical asthenospheric composition. The majority of garnet compositions fall into the G9 classification field. Titanium shows a distinct partition trend that correlates with depletion. Garnets have well developed alteration reaction rims, especially at shallower depths. Geothermobarometric calculations for four-phase peridotites are comparable with the results from other studies. However, the temperature estimates obtained by T(BKN90) are slightly overestimated and, in contrast, the pressure estimates from P(BBG08) are slightly underestimated. Other assemblages have considerable calculated pressure and temperature conditions and were best fitted for the regional conductive geotherm. The mantle xenoliths show pressures ranging from 22 to 56 kb and temperatures from 753 to 1344 °C that characterize an extensive sampling depth range from 70 to 190 km. Three of the samples extend into the diamond stability field. The obtained P-T data for mantle xenoliths cluster along a 44.0±2.0 mWm⁻² conductive Kaapvaal craton continental geotherm, being slightly higher than that of the average thermal state estimate for the craton.
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Sonwa, Cyrille Stephane Tsakou. "Analysis of the structural geology of the high-grade metamorphic rocks in part of the Kakamas terrane of an area adjacent to the Neusspruit shear zone South of the orange river, Northern Cape, South Africa." University of the Western Cape, 2021. http://hdl.handle.net/11394/8257.

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>Magister Scientiae - MSc
The Proterozoic Namaqua-Natal Province comprises highly deformed rocks of medium to high grade metamorphism and is bordering the Archean Kaapvaal Craton to the west, south and east in South Africa. The sector to the west of the Craton, namely the Namaqua Sector, is structurally complex and subdivided from west to east into the Bushmanland Subprovince, the Kakamas and Areachap terranes of the Gordonia Subprovince and the Kheis Subprovince. The prominent Neusberg Mountain Range, with exposures to the north and south of the Orange River in the Kakamas Terrane constitutes evidence of crustal shortening as a result of continental collision of the Namaqua Sector block with the Kaapvaal Craton during the Namaquan Orogeny. The Mesoproterozoic Korannaland Group in the Kakamas Terrane is affected by faulting, folding and shearing.
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Coetzee, Megan. "Geochemistry of selected South African group I, group II and transitional kimberlites located on and off the Kaapvaal craton." Master's thesis, University of Cape Town, 2004. http://hdl.handle.net/11427/4192.

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Includes bibliographical references.
Eighteen Jurassic to Cretaceous South African kimberlites representative of group 1, group 11 and transitional varieties that have been emplaced through both the Archean Kaapvall craton (on-craton) and Proterozoic Namaqua-Natal belt (off-craton), have been selected for a comparative study aimed at characterising their geochemistry and source region compositions, as well as understanding the petrogenetic processes that have affected them. The petrography of the analysed kimberlites is similar to typical group 1 and group 11 kimberlites, characterised by deformed and anhedrarl olivine and phlogopite macrocrysts, with more subhedral to euhedral olivine and phlogopite phenocrysts and microphenocrysts, set in a groundmass of mostly serpentine, calcite and phlogopite (group 1 kimberlites), or calcite, serpentine, phlogopite and diopside (group 11 kimberlites). The transitional kimberlites tend to show intermediate characteristics, with the on-and off-craton transitional kimberlites showing more similarity to group 1 and group 11 kimberlites, respectively.
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Nethenzheni, Sedzani Shane. "The geochemistry, geochronology and petrogenetic characteristics of two granitic suites on the eastern margin of the Namaqua Sector, Namaqua-Natal Mobile Belt, South Africa." Thesis, University of the Western Cape, 2016. http://hdl.handle.net/11394/5209.

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Abstract:
>Magister Scientiae - MSc
The group of granites on the eastern margin of the Mesoproterozoic Namaqua sector of the polydeformed and highly metamorphosed Namaqua-Natal Province of southern Africa is known as the Keimoes Suite. The suite includes mixtures of diverse rock types not belonging to a single intrusive series and so it should be subdivided into more than one intrusive suite. The exact definition, extent, distribution and petrogenesis of these granites have been poorly defined in the past, with various authors defining the suite differently due to the lack of proper geochronology and geochemical data. The exact contact between the Namaqua sector and Kaapvaal Craton together with the role of the suite to the Namaqua tectonic evolution is still unclear. The granites of the Keimoes Suite are thought to mark the contact between the Namaqua sector and the Kaapvaal Craton. This study seeks to address the above mentioned problems by making use of new geochronology, isotope, major and trace element geochemistry together with petrography. The granites of the Keimoes Suite were previously grouped based on their degree of deformation. The geochronology, undertaken as part of this study, has proven that this classification is unfounded. The degree of foliation in these granites appears to be largely controlled by the abundance of platy minerals, such as biotite and muscovite, together with the intrusion mechanism, with deformational processes, such as shearing, playing a secondary role. The geochronology, together with geochemistry has helped to redefine the previously defined Keimoes Suite so that two well defined separate suites are recognized and the third is poorly defined due to lack of more samples of that age group. The new classification or grouping of the granites of the eastern Namaqua sector allows a more detailed examination of the tectonic evolution of this region. A member of the 1225 to 1200 Ma early syn-tectonic granites, the Josling Granite, shows a strongly developed foliation and was derived from a depleted source with a relatively low continental crustal component. This granite intruded during the time of arc accretion, and is associated with, and partly responsible for the D₁ deformation and M₁ metamorphism recognized in most of the rocks of the eastern terranes of the Namaqua sector. In terms of age, the syn-tectonic granites of the Augrabies Suite extend from 1200 to 1120 Ma and were largely derived from depleted sources with variable but more substantial amounts of continental crustal components as compared to the early syn-tectonic granite. The granites of this suite intruded during the period of peak D₂ deformation with peak magmatism between 1180 - 1135 Ma, and particularly around 1150 Ma, during the peak of metamorphism (M₂) caused by, and associated with these voluminous intrusions. The Keimoes Suite can now be defined as comprising granites of late- to post-tectonic age relative to the 1.2 - 1.08 Ga Namaquan Orogeny with magmatism occurring on the western side of the Kaapvaal Craton. The 1116 to 1066 Ma Keimoes Suite intruded during the stage of the Namaquan Orogeny in which there was continued indentation of the Kaapvaal Craton into the Namaqua sector with wrenching and shearing causing the development of rifting into which the granites intruded. The Keimoes Suite granites were derived from continental crustal sources and incorporated varying degrees of depleted source components. The intrusives and extrusives of this age occured after the main collisional event between the Namaqua Sector and the Kaapvaal Craton and are associated with the D₃ deformational event, imparting the thermal conditions leading to the M₃ metamorphic event of the rocks within both the Kakamas and Areachap Terranes. The suites mark the suture between the Archean Kaapvaal Craton and the Proterozoic Namaqua sector. The compositions of the granites of the individual suites were mainly controlled by the source with the degree of partial melting exerting a major control. The proportion of entrained peritectic assemblages and accessory minerals played a major role in controlling the compositions of the granites, particularly those of the trace elements. Variations within the compositions of the same suite are due to source heterogeneities. Generally, fractionation processes played a secondary role in influencing the composition of the granites.
Council for Geoscience and National Research Foundation
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Schneider, Kathrin [Verfasser]. "Constraints on the Magmatic History of Paleo- and Mesoarchean Meta-Igneous Rocks of the Eastern Kaapvaal Craton, Southern Africa / Kathrin Schneider." Berlin : Freie Universität Berlin, 2019. http://d-nb.info/1176632248/34.

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Books on the topic "Kaapvaal"

1

Truswell, J. F. Early Proterozoic red beds on the Kaapvaal craton. Johannesburg: University of the Witwatersrand, 1990.

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Dr, Jones Alan G., Carlson R. W. 1954-, and Grutter Herman, eds. A tale of two cratons: The Slave-Kaapvaal workshop. Amsterdam: Elsevier, 2004.

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Kröner, Alfred, and Axel Hofmann, eds. The Archaean Geology of the Kaapvaal Craton, Southern Africa. Cham: Springer International Publishing, 2019. http://dx.doi.org/10.1007/978-3-319-78652-0.

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Weilers, B. F. A review of the Pongola Supergroup and its setting on the Kaapvaal Craton. Johannesburg: University of the Witwatersrand, 1990.

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De Zeeuwse kaapvaart tijdens de Spaanse Successieoorlog 1702-1713. Middelburg: Koninklijk Zeeuwsch Genootschap der Wetenschappen, 1986.

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Reine, R. B. Prud'homme van. Kapers op de kust: Nederlandse kaapvaart en piraterij 1500-1800. Vlissingen: ADZ, 1991.

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Roemloos vergaen: Compendium van verloren gegane schepen,1500-1800 : Oost-Indische Compagnie, West-Indische Compagnie, Groenlandse Compagnie, Kaapvaart, marine, koopvaardij, walvisvaart en visserij. Amsterdam: De Bataafsche Leeuw, 2011.

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Hofmann, Axel, and Alfred Kröner. The Archaean Geology of the Kaapvaal Craton, Southern Africa. Springer, 2019.

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(Editor), A. G. Jones, R. W. Carlson (Editor), and H. Grutter (Editor), eds. A Tale of Two Cratons: The Slave Kaapvaal Workshop. Elsevier Science, 2004.

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The Distribution of radioelements in Archaean granites of the Kaapvaal Craton, with implications for the source of uranium in the Witwatersrand Basin. Johannesburg: University of the Witwatersrand, 1989.

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Book chapters on the topic "Kaapvaal"

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Arndt, Nicholas. "Kaapvaal Craton, South Africa." In Encyclopedia of Astrobiology, 1319. Berlin, Heidelberg: Springer Berlin Heidelberg, 2015. http://dx.doi.org/10.1007/978-3-662-44185-5_1894.

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Arndt, Nicholas. "Kaapvaal Craton, South Africa." In Encyclopedia of Astrobiology, 885. Berlin, Heidelberg: Springer Berlin Heidelberg, 2011. http://dx.doi.org/10.1007/978-3-642-11274-4_1894.

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Arndt, Nicholas. "Kaapvaal Craton, South Africa." In Encyclopedia of Astrobiology, 1. Berlin, Heidelberg: Springer Berlin Heidelberg, 2021. http://dx.doi.org/10.1007/978-3-642-27833-4_1894-4.

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Arndt, Nicholas. "Kaapvaal Craton, South Africa." In Encyclopedia of Astrobiology, 1. Berlin, Heidelberg: Springer Berlin Heidelberg, 2014. http://dx.doi.org/10.1007/978-3-642-27833-4_1894-3.

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Kröner, Alfred, J. Elis Hoffmann, Jean M. Wong, Hong-Yan Geng, Kathrin P. Schneider, Hangqiang Xie, Jin-Hui Yang, and Noah Nhleko. "Archaean Crystalline Rocks of the Eastern Kaapvaal Craton." In Regional Geology Reviews, 1–32. Cham: Springer International Publishing, 2019. http://dx.doi.org/10.1007/978-3-319-78652-0_1.

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Luskin, Casey, Allan Wilson, Digby Gold, and Axel Hofmann. "The Pongola Supergroup: Mesoarchaean Deposition Following Kaapvaal Craton Stabilization." In Regional Geology Reviews, 225–54. Cham: Springer International Publishing, 2019. http://dx.doi.org/10.1007/978-3-319-78652-0_9.

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Hofmann, Axel, Carl R. Anhaeusser, John Dixon, Alfred Kröner, Lopamudra Saha, Allan Wilson, and Hangqiang Xie. "Archaean Granitoid–Greenstone Geology of the Southeastern Part of the Kaapvaal Craton." In Regional Geology Reviews, 33–54. Cham: Springer International Publishing, 2019. http://dx.doi.org/10.1007/978-3-319-78652-0_2.

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Wabo, H., F. Humbert, M. O. de Kock, G. Belyanin, U. Söderlund, L. P. Maré, and N. J. Beukes. "Constraining the Chronology of the Mashishing Dykes from the Eastern Kaapvaal Craton in South Africa." In Springer Geology, 215–61. Singapore: Springer Singapore, 2018. http://dx.doi.org/10.1007/978-981-13-1666-1_6.

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Glikson, Andrew Y. "Pre-3.2 Ga Evolution and Asteroid Impacts of the Barberton Greenstone Belt, Kaapvaal Craton, South Africa." In The Archaean: Geological and Geochemical Windows into the Early Earth, 73–96. Cham: Springer International Publishing, 2014. http://dx.doi.org/10.1007/978-3-319-07908-0_7.

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Jacobs, J., and R. J. Thomas. "Oblique collision at about 1.1 Ga along the southern margin of the Kaapvaal continent, south-east Africa." In Active Continental Margins — Present and Past, 322–33. Berlin, Heidelberg: Springer Berlin Heidelberg, 1994. http://dx.doi.org/10.1007/978-3-662-38521-0_9.

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Conference papers on the topic "Kaapvaal"

1

de Wit, M. J., and C. M. Doucouré. "A feedback from the Kaapvaal Craton Project." In 7th SAGA Biennial Technical Meeting and Exhibition. European Association of Geoscientists & Engineers, 2001. http://dx.doi.org/10.3997/2214-4609-pdb.143.17.1.

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Durrheim, R. J., and R. W. E. Green. "Seismic Velocity Structure Of The Central Kaapvaal Craton." In 1st SAGA Biennial Conference and Exhibition. European Association of Geoscientists & Engineers, 1989. http://dx.doi.org/10.3997/2214-4609-pdb.222.015.

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Webb, S. J. "Gravity And Geoid Investigations Of The Kaapvaal Craton." In 5th SAGA Biennial Conference and Exhibition. European Association of Geoscientists & Engineers, 1997. http://dx.doi.org/10.3997/2214-4609-pdb.223.022.

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Heckel, Catharina, Alan Woodland, Jolien Linckens, and Sally A. Gibson. "Different types of sheared peridotites from Lesotho (Kaapvaal craton)." In Goldschmidt2022. France: European Association of Geochemistry, 2022. http://dx.doi.org/10.46427/gold2022.10998.

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Corner, B. "The Nature Of The Deep Crust Of The Kaapvaal Craton." In 3rd SAGA Biennial Conference and Exhibition. European Association of Geoscientists & Engineers, 1993. http://dx.doi.org/10.3997/2214-4609-pdb.224.011.

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Tinker, J. H., and M. J. de Wit. "Seismic Stratigraphy of Neoarchean-Paleoproterozoic Cover of the Kaapvaal Craton." In 7th SAGA Biennial Technical Meeting and Exhibition. European Association of Geoscientists & Engineers, 2001. http://dx.doi.org/10.3997/2214-4609-pdb.143.19.3.

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Wright, C., S. J. Webb, and T. K. Nguuri. "Broadband Seismological Studies On The Kaapvaal Craton Data Acquisition And Research Objectives." In 5th SAGA Biennial Conference and Exhibition. European Association of Geoscientists & Engineers, 1997. http://dx.doi.org/10.3997/2214-4609-pdb.223.052.

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Chatu, A., M. Q. W. Jones, and S. J. Webb. "Thermal Modelling of The Kaapvaal Lithosphere: Implications for the Bushveld Tomographic Anomaly." In 8th SAGA Biennial Technical Meeting and Exhibition. European Association of Geoscientists & Engineers, 2003. http://dx.doi.org/10.3997/2214-4609-pdb.144.16.

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Wang, Hao, and Jin-Hui Yang. "Widespread Magmatism and Metamorphism at 3.2 Ga in the Eastern Kaapvaal Craton, Southern Africa." In Goldschmidt2020. Geochemical Society, 2020. http://dx.doi.org/10.46427/gold2020.2724.

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Burness, Sara, Katie Smart, Sebastian Tappe, and Emilie Thomassot. "Cycling of surficial sulphur into the lithospheric mantle: constraints from the Kaapvaal craton root." In Goldschmidt2021. France: European Association of Geochemistry, 2021. http://dx.doi.org/10.7185/gold2021.3538.

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