New U–PB baddeleyite ages of mafic dyke swarms of the west African and amazonian cratons : Implication for their configuration in supercontinents through time
Summary, in English
Eight different generations of dolerite dykes crosscutting the Paleoproterozoic basement in West Africa and one in South America were dated using the high precision U–Pb TIMS method on baddeleyite. Some of the individual dykes reach over 300Â km in length and they are considered parts of much larger systems of mafic dyke swarms representing the plumbing systems for large igneous provinces (LIPs). The new U–Pb ages obtained for the investigated swarms in the southern West African Craton (WAC) are the following (oldest to youngest): 1791 ± 3Â Ma for the N010° Libiri swarm, 1764 ± 4Â Ma for the N035° Kédougou swarm, 1575 ± 5 for the N100° Korsimoro swarm, ~1525–1529Â Ma for the N130° Essakane swarm, 1521 ± 3Â Ma for the N90° Sambarabougou swarm, 915 ± 7Â Ma for the N070° Oda swarm, 867 ± 16Â Ma for the N355° Manso swarm, 202 ± 5Â Ma and 198 ± 16Â Ma for the N040° Hounde swarm, and 200 ± 3Â Ma for the sills in the Taoudeni basin. The last ones are related to the Central Atlantic Magmatic Province (CAMP) event. The Hounde swarm is oblique to the dominant radiating CAMP swarm and may be linked with the similar-trending elongate Kakoulima intrusionÂ in Guinea. In addition, the N150° Käyser swarm (Amazonian craton, South America) is dated at 1528 ± 2Â Ma, providing a robust match with the Essakane swarm in a standard Amazonia-West African craton reconstruction, and resulting in a combined linear swarm >1500Â km by >1500Â km in extent. The Precambrian LIP barcode ages of c. 1790, 1765–1750, 1575, 1520, 915. 870Â Ma for the WAC are compared with the global LIP record to identify possible matches on other crustal blocks, with reconstruction implications. These results contribute to the refinement of the magmatic ‘barcode’ for the West African and Amazonian cratons, representing the first steps towards plausible global paleogeographic reconstructions involving the West African and Amazonian cratons.
- Lithosphere and Biosphere Science
- ISSN: 2197-9553
- ISSN: 2197-9545