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World Continent General Considerations For Africa Geological History. The African continent comprises five ancient Precambrian cratons, Kaapvaal, Zimbabwe, Tanzania, Congo, and West Africa. Which formed 2 billion to 3.6 billion years ago and have been stable since then; These cratons limited by the young crease bands formed between 2 billion and 300 million years ago. These rocks folded and deformed (i.e., they have altered in composition and formation by heat and pressure). Precambrian rock outcrops appear 57% on the surface of the continent. While the rest of the surface comprises younger sediments and most undeveloped volcanic rocks.
The oldest rock comes from the arch age (4.6 to 2.5 billion years). In the so-called granite-gneiss-greenstone terrain of the Kaapvaal Craton in Zimbabwe. And the Congo. They form strip gneiss, several types of granite and well-preserved volcanic rocks. That show evidence of underwater extrusion (ie, discharge of molten rock material) and high-temperature formation. The Komati rock is a diagnosis of these volcanic rock sequences and only limited to Aeon Archean. The craton is stable at the ancient end by a good agreement of granite intrusive structures. Covered by clastic sediments, which contain important gold and uranium deposits (eg, the Witwatersrand scheme in South Africa).
World Continent General Considerations For Africa Geological History
The Proterozoic Eternal (250 million years ago, 541 million years ago) characterized by the form of several moving belts. Which were strong and deformed between cratons and long and narrow areas of deformed rocks? This may be for the means of cratons the tectonic plates. The oldest moving belt is in Archean rocks, such as the Limpopo belt that separates Kaapvaal from the Zimbabwe Craton. A younger belt formed throughout the thermal tectonic events. The continent is known as Eburnian (2.2 to 1.8 billion years ago). Which led to the Burmese combination of West Africa. The Ubendian combination of central and eastern Africa, and many rocks in Angola. Found younger bands from Kibaran thermotectonic event (from 1.2 billion to 950 million years) in eastern and southern Africa.
Sign of the end of the Precambrian main training venture band called Pan-African Interlude (making 950 550 million years). Which produces a double fold along the east coast of Mozambique Africa, Dharma and Kadan. The band extends from Namibia to the Congo and Zambia. Between Angola and Gabon, between Dahomey and Ghana and Algeria. The Akhagar belt, the Democratic Republic of the Congo with the Mauritanide from Senegal to Morocco.
It recorded a unique Late Precambrian evolution in the so-called Northeast African and Arabian Nubian Shields. There, it produces many volcanic rocks and granites in the island environment. The marginal basins are like the current southwestern Pacific. These rocks accumulate in the ancient African continent, and their edges are next to the current Nile. Through the same subduction practice as the subduction manner observed today. (Ditching involves lowering the edge of the lithospheric plate below the edge of another plate that the other plate collides).
World Continent General Considerations
The interior of the ancient craton not affected by earlier tectonic events. Accumulated internal sedimentary and volcanic sequences in the large basin. Most important of these is the Transvaal Basin in Kaapvaal. Which has important iron ore deposits; the Congo Basin. The West African Basin, with thick Late Proterozoic sediments, including a prominent horizon. It marks an important glacier event at the end of the Precambrian period.
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After, the Precambrian the geological history of Africa characterized by these events. South Africa (Cape fold belt) Paleozoic (541 to 252 million years ago) forming fold belts. Morocco (anti-Atlas belt) and Mauritania (The Mauritania belt), bordering the oldest craton. The basalt volcano was large, in South Africa, Namibia, and East Africa, known as the Karoo scheme. Likely to start with 230 billion in the supercontinent of the Gondwana landslide Year.
The collision between the African and European plates, and the closure of the ancestral Mediterranean (Tethys Sea). A young mountain belt formed in northwestern Africa 100 million to 40 million years ago. New generation (That is, around the past 66 million years), which led to open the Red Sea. Develop the East African Rift Valley from the Arab Plate during the Northeast period broke the original African bark. Several long valleys along the rift accompanied by extensive volcanic movement.
World Continent General Considerations