Zimbabwe Craton

Southern Africa showing location of Zimbabwe Craton

The Zimbabwe Craton is an area in Southern Africa of ancient continental crust, being a part of the ancient continent of Western Gondwana, with rocks dating back to the early Archean Eon, possibly as early as 3.46 billion years ago (Ga.).^[1] The craton is named after the country of Zimbabwe where the majority of the craton is located. The rocks of the Zimbabwe Craton are separated from the rocks of the Kaapvaal Craton to the southeast by the 250 km wide Limpopo Belt of granulite facies tectonites. The Limpopo belt formed contemporaneously with the Zimbabwe and Kaapvaal cratons, but remained geologically active until much later. It was only in the late Archean, ca. 2.8-2.5 Ga., that the two cratons were stabilized together and that high-grade metamorphism ceased in the Limpopo Belt. North of the Zimbabwe Craton is the Zambezi Belt.^[2]

Origin

The Zimbabwe Craton formed from the suture of two smaller blocks, the Tokwe Segment to the south and the much smaller Rhodesdale Segment (aka Rhodesdale gneiss), to the north. The rocks of these segments have been dated to as early as 3.46 Ga.^[1] The Tokwe Segment probably stabilzed about 3.3 Ga., and there is evidence that the Rhodesdale Segment stabilzed about the same time.<ref name=Dirks-2002">Dirks, P. H. G. M. and Jesma, H. A. (2002). "Crust–mantle decoupling and the growth of the Archaean Zimbabwe Craton". Journal of African Earth Sciences 34: 157–166. doi:10.1016/s0899-5362(02)00015-5. </ref>^[3]

The synchroneity and extent of the Tokwe Segment is considered strong evidence supporting a predominantly intra-cratonic origin for the Late Archaean greenstone belts of Zimbabwe and refuting an arc accretion origin for the craton.^[3]

References

1 2 Wilson, J. F.; Nesbitt, R. W.; and Fanning, C. M. (1995). "Zircon geochronology of Archaean felsic sequences in the Zimbabwe Craton: a revision of greenstone stratigraphy and a model for crustal growth". In Coward, M. P. and Ries, A. C. Early Precambrian processes. Geological Society Special Publications, issue 95. London: Geological Society of London. pp. 109–126. ISBN 978-1-897799-36-9.
↑ Jelsma, H. A. and Dirks, P. H. G. M. (2002). "Neoarchean Tectonic Evolution of the Zimbabwe Craton". In Fowler, C. M. R.; Ebinger, C. L. and Hawkesworth, C. J. The Early Earth: Physical, Chemical and Biological Development. Geological Society Special Publications, issue 199. London: Geological Society of London. pp. 183–211. ISBN 978-1-86239-109-3.
1 2 Blenkinsop, T. G.; Martin, A.; Jelsma, H. A. and Vinyu, M. L. (1997). "The Zimbabwe Craton". In de Wit, M. J. and Ashwal, L. D. Greenstone Belts. Oxford, England: Clarendon Press. pp. 567–580. ISBN 978-0-19-854056-4.

Major African geological formations

Plates	African Plate Somali Plate Madagascar Plate Seychelles Plate

Cratons and Shields	Arabian-Nubian Shield Congo Craton Kaapvaal Craton Kalahari Craton Saharan Metacraton Tanzania Craton Tuareg Shield West African Craton Zimbabwe Craton

Shear zones	Aswa Dislocation Broodkop Shear Zone Central African Shear Zone Chuan Shear Zones Foumban Shear Zone Mwembeshi Shear Zone Todi Shear Zone Western Meseta Shear Zone

Orogens	Alpide Orogen Cape Fold Belt Damara Orogen East African Orogen Eburnean Orogen Gondwanide Orogen Kuunga Orogen Mauritanide Belt Pan-African orogens Terra Australis Orogen

Rifts	Afar Triangle Anza trough Bahr el Arab rift Benue Trough Blue Nile rift East African Rift Gulf of Suez Rift Lamu Embayment Melut Basin Muglad Basin Red Sea Rift Sangha Aulacogen Atbara rift White Nile rift

Sedimentary basins	Angola Basin Aoukar Blue Nile Basin Chad Basin Congo Basin Douala Basin El Djouf Foreland Karoo Basin Gabon Basin Iullemmeden Basin Kufra Basin Murzuq Basin Niger Delta Basin Ogaden Basin Orange River basin Ouled Abdoun Basin Owambo Basin Reggane Basin Rio del Rey Basin Sirte Basin Somali Coastal Basin Taoudeni basin Tanzania Coastal Basin Tindouf Basin Turkana Basin

Mountain ranges	Aïr Mountains Atlas Mountains Aurès Mountains Bambouk Mountains Blue Mountains Cameroon line Central Pangean Mountains Chaillu Mountains Drakensberg Ethiopian Highlands East African mountains Great Escarpment Great Karas Mountains Guinée forestière Imatong Mountains Jebel Uweinat Loma Mountains Mandara Mountains Marrah Mountains Mitumba Mountains Nuba Mountains Rif Mountains Rwenzori Mountains Sankwala Mountains Serra da Leba Serra da Chela Teffedest Mountains Tibesti Mountains

This article is issued from Wikipedia - version of the Saturday, September 12, 2015. The text is available under the Creative Commons Attribution/Share Alike but additional terms may apply for the media files.