Editing Congo Craton

{{short description|Precambrian craton that with four others makes up the modern continent of Africa}}
[[Image:Cratons West Gondwana.svg|thumb|Approximate location of [[Mesoproterozoic]] (older than 1.3&nbsp;Ga) cratons within South America–Africa in their Gondwana configuration ({{Circa}} 550-130&nbsp;Ma).]]

The '''Congo Craton''', covered by the [[Palaeozoic]]-to-recent [[Congo Basin]], is an ancient [[Precambrian]] [[craton]] that with four others (the [[Kaapvaal Craton|Kaapvaal]], [[Zimbabwe Craton|Zimbabwe]], [[Tanzania Craton|Tanzania]], and [[West African Craton|West African]] cratons) makes up the modern [[continent]] of [[Africa]]. These cratons were formed between about 3.6 and 2.0 billion years ago and have been [[tectonic]]ally stable since that time. All of these cratons are bounded by younger [[Fold and thrust belt|fold belt]]s formed between 2.0 billion and 300 million years ago.

The Congo Craton occupies a large part of central southern Africa, extending from the Kasai region of the [[Democratic Republic of the Congo|DRC]] into [[Sudan]] and [[Angola]]. It forms parts of the countries of [[Gabon]], [[Cameroon]], and the [[Central African Republic]]. A small portion extends into [[Zambia]] as well, where it is called the [[Bangweulu Block]].

==Congo–São Francisco==
The Congo Craton and the [[São Francisco Craton]] are stable Archaean blocks that formed a coherent landmass until the opening of the South Atlantic Ocean during the break-up of Gondwana ({{Circa}} 2000–130&nbsp;Ma).<ref>{{Harvnb|Ernst|Pereira|Hamilton|Pisarevsky|2013|loc=Conclusions, p. 116}}</ref>  They stabilised during the [[Transamazonian orogeny]] and [[Eburnean Orogeny]] and have been affected by a long series of orogens since resulting in similar sequences on both blocks.<ref>{{Harvnb|Pedreira|De Waele|2008|p=33–34}}</ref>

Congo–São Francisco experienced three [[large igneous province]] (LIP) events at 1380–1370&nbsp;Ma, {{Circa}} 1505&nbsp;Ma, and {{Circa}} 1110&nbsp;Ma.  The relative position of Congo–São Francisco within the supercontinent [[Columbia (supercontinent)|Nuna/Columbia]] can be reconstructed because these LIP events also affected other Precambrian continental blocks.  Within Nuna the northern part of [[Siberia (continent)|Siberia]] was located adjacent to western São Francisco.  1110&nbsp;Ma dyke swarms in Angola are absent in Siberia but coincide with the Umkondo LIP on the [[Kalahari Craton]] and magmatic event in the [[Bundelkhand Craton]] in India, the [[Amazonian Craton]] in South America, and the [[Keweenawan Supergroup|Keweenawan Rift]] in [[Laurentia]] (although the latter was located far from the other continental blocks).<ref>{{Harvnb|Ernst|Pereira|Hamilton|Pisarevsky|2013|loc=Abstract}}</ref>
A series of 1500&nbsp;Ma dyke swarms also support the close relation between Congo–São Francisco and Siberia: Kuonamka in Siberia and Curaçá and Chapada Diamantina in São Francisco and Angola.  These dyke swarms radiate from a [[mantle plume]] centre located in what is now north-eastern Siberia.  Magmatic events in Congo (Kunene) and Siberia (Chieress) at 1384&nbsp;Ma also corroborate the closeness of these two continents during at least 120 million years.<ref>{{Harvnb|Pisarevsky|Elming|Pesonen|Li|2014|loc=Congo/ São Francisco and Siberia}}</ref>

It is possible that the 1110&nbsp;Ma LIP in Congo–São Francisco, Amazonia, and India was part of a much larger event that also involved West Africa and Kalahari (with a possible but unlikely link to the 1075&nbsp;Ma Warakurna LIP in Australia).  However, while the palaeo-latitudes of India and Kalahari are well constrained, those of Amazonia and Congo–São Francisco are not, making any plate tectonic reconstruction speculative.<ref>{{Harvnb|de Kock|Ernst|Söderlund|Jourdan|2014|loc=Other 1.1 Ga LIPs?, pp. 139–140}}</ref>

At the time for the formation of the supercontinent [[Gondwana]] at {{Circa}} 550&nbsp;{{Abbr|Ma|million year ago}} the Congo Craton formed the already amalgamated central African landmass.  The southern and eastern margins (modern coordinates) of this landmass was made of the [[Archean|Archaean]] Angola-Kasai block and Tanzanian Craton.  These proto-Congo blocks were deformed in the [[Palaeoproterozoic]] [[Eburnean orogeny]] but later stabilised.<ref>{{Harvnb|De Waele|Johnson|Pisarevsky|2008|loc=Introduction, pp. 
127–128}}</ref>

===West Congo Belt===
Before the opening of the South Atlantic the São Francisco and Congo cratons were connected by a "cratonic" bridge, the Bahia–Gabon Bridge.  The most recent orogenic event on this bridge occurred at 2&nbsp;Ga, so the connection between São Francisco and Congo must have formed during the Palaeoproterozoic.  South of this cratonic bridge the Araçuaí–West Congo orogen evolved in the Neoproterozoic in a sea basin made of oceanic crust, an embayment in the São Francisco–Congo continent.<ref>{{Harvnb|Babinski|Pedrosa-Soares|Trindade|Martins|2012|loc=Geotectonic setting, p. 452}}</ref>

giatomooooo  gugu gagaga


The West Congo [[Pan-African orogeny|Pan-African]] Belt includes major m''agmatic events at {{Circa}} 1000 and 910&nbsp;Ma.  In the Early Neoproterozoic, the western edge of Congo Craton was the lo''cation for the initial rifting of Rodinia before its break-up.  During the Neoproterozoic, Central Congo or [[Bas-Congo]] became a [[passive margin]] on which was deposited {{Convert|4000|m|abbr=on}} sediments.  At the end of the Neoproterozoic, Bas-Congo was only affected by the Pan-African orogeny at 566&nbsp;Ma to a limited extent protected by this passive margin and by the thickness of the craton.
At 1000&nbsp;Ma [[peralkaline]] magmatism initiated an early [[transtension]]al setting along the western edge of the Congo Craton.  An LIP at {{Circa}} 930–920&nbsp;Ma was followed by [[felsic]] magmatism between {{Circa}} 920–910&nbsp;Ma which had a short emplacement interval and resulted in a {{Convert|3000|-|4000|m|abbr=on}} thick sequence.
Mafic-felsic magma sequences ({{Convert|6000|m|abbr=on}} thick) on the western edge of the Congo Craton are similar to those of the [[Paraná and Etendeka traps|Paraná]] and [[Deccan Traps|Deccan]] LIPs, but in the Congo Craton the magma source became shallower with time.  There was no geodynamic activity along the western Congo margin during the Mesoproterozoic.<ref>{{Harvnb|Tack|Wingate|Liégeois|Fernandez-Alonso|2001|loc=Introduction, pp. 301–302}}</ref>

==See also==
* [[Damara Orogeny]]

==References==
===Notes===
{{reflist}}

===Sources===
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{{Refend}}

{{Continents of Earth}}
{{Major African geological formations}}

[[Category:Cratons]]
[[Category:Archean Africa]]
[[Category:Proterozoic Africa]]
[[Category:Geology of Africa]]
[[Category:Historical continents]]
[[Category:Historical geology]]
[[Category:Geology of the Democratic Republic of the Congo|Craton]]
[[Category:Geology of the Republic of the Congo|Craton]]