Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
Results
Showing 1 to 20 of 24 for “"Kaapvaal"”.
-
Chemostratigraphy of the Early Paleoproterozoic carbonate successions (Kaapvaal and Wyoming cratons)
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 …
-
Petrology and geochemistry of the diamondiferous K-richteriteand leucite-bearing Kareevlei Kaapvaal lamproite
… is the first mine on the evolved leucite-bearing Kaapvaal lamproite. These rock types have generally been believed to be non-diamondiferous or at least sub-economic and as a result, their petrogenesis has remained poorly constrained as the exploration programs focused mainly on the unevolved …
-
Nominally volatile-free mantle minerals: a reservoir for water and fluorine in the Kaapvaal Craton
… Africa) and margin (Mothae, Lesotho) of the Kaapvaal craton has placed important constraints on the capacity of olivine and pyroxenes to store volatiles. Cryptically metasomatised olivine is found to be a major host of fluorine (up to 196 ppm). A new incorporation mechanism involving triple …
-
Stratigraphic and structural interpretation of seismic reflection data across selected sections of the Kaapvaal Craton
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 …
-
A thermotectonic framework for the growth and stabilization of the eastern Kaapvaal craton, southern Africa
… 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 …
-
Thermobarometry and geochemistry of peridotite xenoliths from the southwestern margin of the Kaapvaal craton, South Africa
Globally, there are significant contrasts, both thermally and chemically, between peridotite xenoliths exhumed from Archean, and post-Archean terranes. Studies of the thermal structure of the lithosphere, in combination with surface heat flow data, suggest that thermal gradients beneath cratonic …
-
S-wave velocity structure beneath the Kaapvaal Craton from surface-wave inversions compared with estimates from mantle xenoliths
… 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, …
-
Petrogenesis of Mesoarchean high-K rocks in the Kaapvaal Craton: Investigating the Boesmanskop Alkaline Complex and Salisbury Kop batholith
… suite, situated on the eastern margin of the Kaapvaal Craton. The BAC consists of small intrusions at the southern end of the Barberton greenstone belt, recording shear deformation and containing the most potassic and REE-rich rocks of the GMS suite. In contrast, the SB is a homogeneous …
-
Geochemistry of selected South African group I, group II and transitional kimberlites located on and off the Kaapvaal craton
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 …
-
A comparison of melt depletion, thermal structure and metasomatism of proterozoic mantle lithosphere in the Namaqua-Natal and Rehoboth Provinces of Southern Africa
… Late Cretaceous kimberlites to the west of the Kaapvaal craton in two Proterozoic terranes: Hoedkop and Pofadder in the north-western Namaqua-Natal Province and Rietfontein and Louwrensia (Gibeon) in the Rehoboth Province. These are used to constrain and compare the thermal structure, the …
-
Petrology and geochemistry of the granitoids of the Halfway House Dome
… signature when compared to GGM suites. The Kaapvaal Craton represents one of only a few areas where pristine mid-Archaean rocks have been preserved. The Archaean Kaapvaal Craton formation took place in two distinct periods, i.e an initial shield-forming stage, which spanned from ~3700 Ma to …
-
The tectonic development of the Namaqua mobile belt and its foreland in parts of the Northern Cape
… West Africa to the south-western margin of the Kaapvaal Craton near Prieska. Its Precambrian tectonic development is characterised by several successive periods of deformation and metamorphism, the last of which - the Namaqua tectogenesis - occurred between c. 0,9 and 1,25 Ga B.P. The northern …
-
A geochemical study of diamonds, diamond inclusion minerals and other mantle minerals from the Klipspringer kimberlites, South Africa
… occur in the north-eastern part of the Kaapvaal craton which is poorly represented in kimberlite and mantle studies. The kimberlites have been dated at 148+-4 Ma and the current study presents the geochemical characteristics of their diamonds, diamond inclusion and mantle …
-
A geochemical study of diamonds from Cullinan diamond mine, South Africa
… and is located in the northeastern region of the Kaapvaal Craton, South Africa. The kimberlite pipe has been dated at 1180 ± 30 Ma and intrudes the Bushveld Igneous Complex (2.05 Ga). This study explores the geochemistry of a suite of one hundred selected diamonds and their associated mineral …
-
Petrology of the micaceous Koidu and Tongo - Tonguma kimberlites, Man Craton, Sierra Leone
… of both micaceous kimberlites and unevolved Kaapvaal lamproite, making classification ambiguous. To successfully classify and constrain the petrogenesis of these rocks, a combination of detailed petrography, and phlogopite, spinel and olivine chemistry is used in this study. The Koidu rocks …
-
The geochemistry of a suite of eclogite xenoliths from the Rietfontein Kimberlite, South Africa
… off-craton kimberlite pipe, located west of the Kaapvaal Craton at 26.75°, 20.04°E and hosts a range of xenocryst lithologies, including peridotite, eclogite and a suite of megacryst minerals. This study focuses on a suite of eclogite xenoliths, which were subject to a detailed petrographical and …
-
A detailed investigation into diamond-bearing xenoliths from Newlands Kimberlite, South Africa
… from Newlands kimberlite, located on the Kaapvaal craton, South Africa. Eighteen peridotitic garnet macrocrysts (1 to 3 cm in size) containing diamond, and one with graphite, consist predominantly of lilac garnet with diamond (or graphite) ± chromite and altered silicates. The garnets are …
-
The geology of the Waterberg group in the southern Portion of the Waterberg basin
… fault-bounded basin in the northern part of the Kaapvaal craton. The basin is bounded in the south by the Murchison lineament and in the north by the southern part of the Pal al a shear zone. The Murchison lineament is interpreted to be a long-lived, fundamental strike-slip fault system. …
-
Trace Element Geochemistry of Compositionally Layered Impact Spherules
… in the Barberton Greenstone Belt (BGB) in the Kaapvaal Craton of South Africa focuses on the heterogeneity of textures and geochemistry produced during the cooling and crystallization of spherules within a vapor plume. Type 4b spherules are layered phyllosilicate spherules with discrete …
Page 1 of 2