Proterozoic geology and regional correlation of the Ghanzi-Makunda area,western Botswana |
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| Institution: | 1. Department of Geological Survey, Private Bag 14, Lobatse, Botswana;2. Department of Geology, University of Botswana, Private Bag 0022, Gaborone, Botswana;3. Jack Satterly Geochronology Laboratory, Royal Ontario Museum, 100 Queen''s Park, Toronto, M5S 2C6, Canada;1. Département de Géologie, Faculté des Sciences, Université Moulay Ismail, Meknès, Morocco;2. Faculté des Sciences et Techniques, Université Sidi Mohammed Ben Abdellah, Fès, Morocco;3. Facultés des Sciences Dhar El Mahraz, Université Sidi Mohamed Ben Abdellah, Fès, Morocco;4. Faculté des Sciences et Techniques, Université Moulay Ismail, Errachidia, Morocco;5. Direction de Géologie, Ministère de la Transition Energétique et du Développement Durable, Rabat, Morocco;6. École Normale Supérieure, Université Sidi Mohamed Ben Abdellah, Fès, Morocco;1. School of Earth Sciences, University of Melbourne, Parkville, Victoria 3010, Australia;2. Department of Geology and Geophysics, Yale University, New Haven, CT 06520, USA;2. TU Dresden, Faculty of Environmental Sciences, Institute of Geography, Helmholtzstr. 10, Dresden, 01069, Germany;3. Senckenberg Naturhistorische Sammlungen Dresden, Museum für Mineralogie und Geologie, Königsbrücker Landstr. 159, Dresden, 01109, Germany;1. Departamento de Geologia Aplicada, Instituto de Geociências e Ciências Exatas, Universidade Estadual Paulista, Avenida 24A, 1515, Rio Claro 13506-900, Brazil;2. Curso de Geologia, Instituto de Geografia, Universidade Federal de Uberlândia, Rodovia LMG 746, Km 1, Monte Carmelo 38500-000, Brazil;3. Departamento de Zoologia, Instituto de Biociências, Universidade Estadual Paulista, Distrito de Rubião Júnior, Botucatu 18618-000, Brazil;4. Instituto de Ciencias Geológicas, Facultad de Ciencias, Iguá 4225, Montevideo 11400, Uruguay;5. Instituto de Energia e Ambiente, Universidade de São Paulo, Avenida Professor Avenida Luciano Gualberto, 1289, São Paulo 05508-010, Brazil;6. Centro de Investigaciones Geológicas, UNLP-CONICET, calle 1, n. 644, La Plata 1900, Argentina;7. Faculdade de Tecnologia, Universidade Estadual de Campinas, R. Paschoal Marmo, 1888, Limeira 13484-332, Brazil;8. Instituto de Geociências, Universidade de São Paulo, Rua do Lago, 562, São Paulo 05508-080, Brazil;9. NEG-LABISE, Department of Geology, Universidade Federal de Pernambuco, Av. Acadêmico Hélio Ramos, Recife 7852, Brazil |
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| Abstract: | The Ghanzi-Makunda area exposes three main Proterozoic assemblages. The oldest rocks belong to the Palaeoproterozoic (Eburnian) Okwa Basement Complex, which consists of porphyritic rhyolitic felsite and granitoids emplaced at 2055±4 Ma. A volcanic sequence named the Kgwebe volcanic complex consists of metarhyolites and metabasalts with interbedded tuff and agglomerate. These metavolcanic rocks represent a bimodal suite of continental tholeiites and high K rhyolites linked to the evolution of the Mesoproterozoic Kibaran orogenic system. Siliciclastic and carbonate rock successions of the Neoproterozoic to early Palaeozoic Ghanzi-Chobe Belt unconformably overlie the Mesoproterozoic Kgwebe volcanic complex. The Ghanzi-Chobe Supergroup comprises the Ghanzi Group and the Okwa Group. In Namibia, felsic lavas with UPb zircon ages of ca 750 Ma occur at the top of lithological units correlated to the Ghanzi Group. The deposition of the Ghanzi Group occured after 1020 Ma and before 750 Ma. In the Okwa Group, detrital zircons extracted from Neoproterozoic sedimentary rocks of the Takatswaane Formation yielded the following dates: 1887±14 Ma, 1246±4 Ma, 1054±5 Ma, 627±6 Ma and 579±12 Ma. The age of 579 ± 12 Ma is considered to represent the maximum depositional age of the Okwa Group. Based on the data in this paper, as well as lithological similarities, the Ghanzi Group is correlated with the Nosib Group of the Damara Belt, while the Okwa Group is correlated with the Nama Group in Namibia. |
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