scholarly journals Constraining the thermal history of an Archean craton: U-Pb thermochronology of lower crustal xenoliths from the Kaapvaal craton, southern Africa

2019 ◽  
Keyword(s):  
Southern Africa ◽  
Thermal History ◽  
Kaapvaal Craton ◽  
History Of ◽  
Crustal Xenoliths ◽  
Lower Crustal

Garnet in cratonic and non-cratonic mantle and lower crustal xenoliths from southern Africa: Composition, water incorporation and geodynamic constraints

2015 ◽  
Vol 270 ◽  
pp. 285-299 ◽  
Author(s):  
Esther Schmädicke ◽  
Jürgen Gose ◽  
Jürgen Reinhardt ◽  
Thomas M. Will ◽  
Roland Stalder
Keyword(s):  
Southern Africa ◽  
Cratonic Mantle ◽  
Crustal Xenoliths ◽  
Lower Crustal

scholarly journals Eclogite and Garnet Pyroxenite Xenoliths from Kimberlites Emplaced Along the Southern Margin of the Kaapvaal Craton, Southern Africa: Mantle or Lower Crustal Fragments?

2020 ◽  
Vol 61 (4) ◽  
Author(s):  
Anton Le Roex ◽  
Christel Tinguely ◽  
Michel Gregoire
Keyword(s):  
Southern Africa ◽  
Kaapvaal Craton ◽  
Crustal Shortening ◽  
Southern Margin ◽  
Accessory Phase ◽  
Garnet Granulite ◽  
Crustal Origin ◽  
Lower Crustal ◽  
Ree Patterns ◽  
Granulite Xenoliths

Abstract Eclogite xenoliths, together with garnet pyroxenites and some mafic garnet granulites, found in kimberlites located along the southern margin of the Kaapvaal craton in southern Africa have been analysed by electron microprobe and mass spectrometry techniques to determine their geochemical characteristics. The majority of eclogites are bimineralic with garnet and omphacitic clinopyroxene in subequal proportions, with rutile as the main accessory phase; a few contain kyanite. Based on K2O in clinopyroxene and Na2O in garnet, the eclogites can be classified as Group II eclogites, and the majority are high-Ca in character. Garnet pyroxenites comprise garnet clinopyroxenites and garnet websterites. Major and trace element concentrations and isotope ratios of reconstituted bulk rock compositions of the eclogites and garnet pyroxenites allow constraints to be placed on depth of origin and likely protolith history. Calculated Fe–Mg exchange equilibration temperatures for the eclogites range from 815 to 1000 °C, at pressures of 1·7 ± 0·4 GPa as determined by REE partitioning, indicating that they were sampled from depths of 50–55 km; i.e. within the lower crust of the Namaqua–Natal Belt. The garnet pyroxenites show slightly lower temperatures (686–835 °C) at similar pressures of equilibration. Initial 143Nd/144Nd and 87Sr/86Sr ratios (calculated to time of kimberlite emplacement) of both lithologies overlap the field for lower crustal samples from the Namaqua–Natal Belt. Further evidence for a crustal origin is found in the similar REE patterns shown by many of the associated garnet granulite xenoliths. Garnet pyroxenites are interpreted to have a similar origin as the associated eclogites but with the mafic protolith having insufficient Na (i.e. low modal plagioclase) to allow for development of omphacitic pyroxene. Metamorphism of the mafic protoliths to these eclogites and garnet pyroxenites is inferred to have occurred during crustal shortening and thickening associated with the collision of the Namaqua–Natal Belt with the Kaapvaal craton at 1–1·2 Ga.

Itumeleng Mosala: Giving Theology Its World, Feet and Hands

2019 ◽  
Vol 6 (2) ◽  
Author(s):  
Takatso Mofokeng
Keyword(s):  
Old Testament ◽  
Southern Africa ◽  
Black People ◽  
Black Consciousness ◽  
History Of ◽  
Black Consciousness Movement

Worthy of celebration is the contribution made by Itumeleng Mosala (hereafter Mosala) to the Black Methodist Consultation, the theological community in Southern Africa, and the Black Consciousness Movement. This article attempts to give theology its world, feet and hands in the person of Mosala. The article departs from the narration of the history of Mosala. It locates Mosala within township life and Old Testament scholarship. Furthermore, the article searches for suitable and effective weapons of intellectual struggle in light of Mosala’s life. The aim of this article is to celebrate the indelible footprints that Mosala made as he communed with black people.

Sign in / Sign up

Export Citation Format

Share Document