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The Kuboos-Bremen Line in Namibia and South Africa: new insights about emplacement and composition

The Kuboos-Bremen Line (KBL) is an alignment of intrusions that extent for 250 km in South Africa and Namibia. Its deepest exposed parts occur near Alexander Bay (RSA) and it continues into the continent trending SW-NE, with the higher intrusion level at the Great Karas Mountains (NAM).

The KBL complexes are divided in three sections: Western KBL is predominantly granitic; Central KBL is composed of granites, syenites, foid-syenites and carbonatites; and Eastern KBL is composed of a field of more than a hundred small carbonate-bearing intrusions (carbonatite dykes, sills and breccia pipes, and lamprophyre and alnöite dyke swarms).

The project aims to understand the genetic relationship between the variety of lithologies at the KBL by: investigating whether the behavior of HFSE and REE in carbonatitic magmas is influenced by source contamination and silicate wall-rock interaction; investigating the cross-cutting relationships of individual complexes and their age data, to understand the progressive evolution from granitic to foid-syenitic/carbonatitic compositions with time and location; and study the rock associations to establish if different magma suites derived from one or variable sources and also if they used the same zone of weakness for ascent and emplacement.

After field work and sample collection from all main complexes the first results from geological mapping and petrography show an even broader variety of lithologies than expected. Individual units from individual complexes share textural and mineralogical similarities and also provide us hints of the role of crustal assimilation in the genesis and magmatic to hydrothermal evolution of these rocks.

Details

Author
Jorge Correia Leite Arthuzzi1, Benjamin F. Walter1, Robert Johannes Giebel2, Lorenz Kemmler3, Jochen Kolb1
Institutionen
1Karlsruhe Institute of Technology (KIT), Chair of Geochemistry and Economic Geology, Adenauerring 20b, 76131 Karlsruhe, Germany;Laboratory of Environmental and Raw Material Analyses (LERA), Adenauerring 20b, 76131 Karlsruhe, Germany; 2Technische Universität Berlin, Institute of Applied Geosciences, Ernst-Reuter-Platz 1, 10587 Berlin, Germany;University of the Free State, Department of Geology, 250 Nelson-Mandela-Drive, Bloemfontein 9300, South Africa; 3Technische Universität Berlin, Institute of Applied Geosciences, Ernst-Reuter-Platz 1, 10587 Berlin, Germany
Veranstaltung
GeoBerlin 2023
Datum
2023
DOI
10.48380/wqzb-ny63