An Integrated Geophysical and Geological Interpretation of the Southern African Lithosphere

Upper Mantle P and S Wave Velocity Structure of the Kalahari Craton and Surrounding Proterozoic Terranes, Southern Africa

“…In addition to the Bushveld event, several other large Precambrian magmatic events occurred in southern Africa. Relics of one of them, the 1.1-Ga Umkondo event, include mafic/ultramafic intrusions (Tshane and Xade Complexes; Figure 5) in central Botswana and flows of mafic lava in southeastern Botswana and northwestern South Africa (Corner & Durrheim, 2018;de Kock et al, 2014;Hanson et al, 2004) where the lower velocities are found (Figures 3 and 5). Fadel et al (2018) suggest that the composition of the crust in these areas may also have been modified.…”

“…However, much remains unknown about the craton, including its geographic size, defined by the presence of thick lithosphere, and the extent to which the lithosphere may have been modified by Proterozoic magmatic events. For example, does thick (>~150 km) lithosphere extend beneath younger terranes surrounding the craton nucleus, such as the Rehoboth Province, Okwa Terrane, and Magondi Belt (Figure 1; e.g., Corner & Durrheim, 2018;Khoza et al, 2013;Eglington & Armstrong, 2004;Griffin et al, 2003)? And how effective have large magmatic events, such as the Bushveld event, been at modifying the composition and structure of the cratonic lithosphere (e.g., Grégoire et al, 2005;Richardson & Shirey, 2008;Viljoen et al, 2009)? To address these questions, we have developed P and S wave velocity models of the upper mantle beneath southern Africa by combining new seismic data from Botswana and South Africa with data from permanent ©2019.…”

“…The greater Kalahari Craton in southern Africa is commonly regarded as an archetypal Archean terrane, and thus, its structure and tectonic evolution have long been studied to learn about tectonic processes during the first two billion years of Earth history (e.g., Begg et al, ; Carlson et al, ; Corner & Durrheim, ; Griffin et al, ; Hartnady et al, ). However, much remains unknown about the craton, including its geographic size, defined by the presence of thick lithosphere, and the extent to which the lithosphere may have been modified by Proterozoic magmatic events.…”

“…The lithosphere in the study area is composed of several Archean and Proterozoic terranes (Figure ). The greater Kalahari Craton is composed of the Archean Kaapvaal (Figure a) and Zimbabwe (Figure b) cratons sutured together by the Archean and Paleoproterozoic Limpopo Belt (Figure i; Corner & Durrheim, ; de Wit et al, ; Dirks & Jelsma, ). The Kalahari Craton is bounded to the northwest by the Paleoproterozoic Okwa Terrane (Figure h) and Magondi Belt (Figure j), and to the south and southwest by the Mesoproterozoic Namaqua‐Natal Belt (Figure d).…”

Lu-Hf analyses of zircon from the Makoppa Dome and Amalia-Kraaipan area: implications for evolution of the Kimberley and Pietersburg blocks of the Kaapvaal Craton

“…The boundaries between the four terranes are based on geophysically defined lineaments, which may or may not have any surface expression, as well as recognisable faults and shear zones, and extensions thereof (Eglington and Armstrong, 2004). As such, they are somewhat dependent on changing interpretations of the geophysical data (Corner and Durrheim, 2018), additional geochronological information and also geochemical data. In the latter respect, the development of the past fifteen years of laser ablation multi-collector inductively coupled mass spectrometry (LA-MC-ICPMS), which permits the determination of the Hf isotopic characteristics of the same zircon grains that provide the age of intrusions, needs to be mentioned.…”