Kalahari Craton - Kalahari Craton With Laurentia, Rodinia, and Gondwana

Kalahari Craton With Laurentia, Rodinia, and Gondwana

Early paleomagnetic studies showed that the Umkondo sills in eastern Zimbabwe correlated with similar mafic intrusions in Botswana and South Africa. It was therefore suggested that the Umkondo igneous province is present over a large part of the Kalahari craton, and also a detached fragment now located in East Antarctica. New paleomagnetic data are in excellent agreement with this. The great majority of the sites have the same polarity suggesting that the dolerites were emplaced during a limited time span, consistent with the geochronology. The pole position places the Kalahari craton off southeast Laurentia within the Rodinia supercontinent. In Laurentia, there is widespread within-plate magmatism coeval with the Umkondo event, raising the possibility that the two igneous provinces were linked within Rodinia.

The Kalahari craton probably converged with southwestern Laurentia between 1060 and 1030 Ma to become part of the Rodinia supercontinent by 1000 Ma. In Rodinia, the Kalahari craton lay near East Antarctica with the Namaqua–Natal orogenic belt facing outboard and away from the Laurentian craton. The Kalahari and Congo cratons probably collided during the assembly of Rodinia, however they could have also been just juxtaposed during the assembly of Gondwana (550–500 Ma) at the end of the Neoproterozoic. In the former case, the transcontinental, ~550 Ma Damaran-Lufilian-Zambezi orogen separating the two cratons would represent a Himalayan-style collisional belt formed by the consumption of a wide ocean. In the later case it may have been a closure of narrow Neoproterozoic basins that developed across previously assembled parts of Rodinia. A third view is that there was a convergence between the Kalahari craton and a composite Congo-Laurentia craton during the assembly of Rodinia, generating the Kibaran-Grenvillian-Llano belts. This orogenic belt system extends for over 3000 km and is over 400 km wide in Africa and is the result of the convergence of Paleoproterozoic/Archaean cratonic blocks forming the Congo craton to the north and a mosaic including the Kalahari, Bangweulu, Tanzania and West-Nilian cratons (hereafter called the Kalahari craton) to the south.

The arc on the flank of Madagascar collided with the African margin at ~640 Ma, and remained attached to the African margin when Madagascar rifted during Gondwana breakup. This ~640 event has been considered to date the collision of India, Madagascar, parts of eastern Antarctica and Kalahari cratons (IMSLEK terranes) with the Congo-Tanzania Craton and Arabian Nubian Shield.