Title: The Geology and Evolution of the Angolan Shield, Congo Craton
Abstract: New U–Pb zircon SHRIMP ages are presented and used together with published age and geochemical data and geological observations to review the Palaeoproterozoic evolution of the Angolan Shield of Central Africa. The shield comprises at least three main crustal tectonic domains: the Central Shield Zone in the east and the Central Eburnean Zone and Lubango Zone in the west. The latter extends south into Namibia as the Epupa Metamorphic Complex and further south is exposed in the Kamanjab and Grootfontein inliers. The magmatic events associated with these tectonic domains have been attributed to the formation of a system of arcs that developed along the active western and southern continental margins of the Congo Craton, with peak magmatic events at 2.0–1.96 Ga (Eburnean Event), 1.88–1.83 Ga (Kamanjab-Bangweulu Event) and 1.80–1.77 Ga (Epupa Event). Along the western continental margin, precise age data confirms the presence of Eburnean granitoids from the Huambo-Andulo region in Angola south to the Kamanjab-Grootfontein region in NW Namibia, a distance of over 1000 km. Geochronology and isotope geochemistry indicates that Neoarchaean crust was involved in the formation of these granitoids. Field relations indicate that this ~2.0 Ga granitic crust was metamorphosed and deformed during orogeny at 1967 Ma. Along the southern continental margin within the Kamanjab Inlier a second magmatic event is documented at c. 1.84 Ga, with inherited grains suggesting the involvement of older crust with a similar age to that exposed in SW Angola and in the nearby Grootfontein-Tsumkwe Inlier. This event may be related to magmatism within the basement to the Lufilian Arc and Bangweulu Block. In the Epupa Metamorphic Complex a third magmatic event is documented at c. 1.77 Ga. It is likely that additional events will be recognized with further high precision geochronology, as is observed for instance along the Andean continental margin which has been periodically active at least since the early Paleozoic.
Publication Year: 2018
Publication Date: 2018-01-01
Language: en
Type: book-chapter
Indexed In: ['crossref']
Access and Citation
Cited By Count: 38
AI Researcher Chatbot
Get quick answers to your questions about the article from our AI researcher chatbot