Dykes of the 1.11 Ga Umkondo LIP, Southern Africa: Clues to acomplex plumbing system
MetadataShow full item record
The Umkondo Large Igneous Province (LIP) is represented by widespread (∼2.0 × 106 km2) mafic intrusions that were rapidly emplaced (1112–1108 Ma) into the Kalahari craton of southern Africa and the formerly adjacent Grunehogna Province of Antarctica during Rodinia assembly. Very few Umkondo-aged dykes have been identified before, resulting in a poor understanding of this LIP's plumbing system and origin. Here we report six new ∼1110 Ma U–Pb TIMS baddeleyite ages for various dolerite dykes, which, when coupled with geochemistry from some of the dykes, suggest association with the Umkondo LIP. The distribution of dykes defines distinct radiating swarms, which locate two separate magmatic centers on the northern margin of the Kalahari craton, and a third less robust center on the SE margin. The Umkondo intrusions’ geochemistry indicates significant partial melting of the sub-continental mantle lithosphere (SCLM) and requires a transient thermal anomaly in the mantle. A viable model sees a mantle plume ascend beneath the craton and split into different portions that moved and ascended to different lithospheric thin-spots along the margins of the craton. As an alternative, the rise in mantle temperature associated with continental aggregation at this time is considered sufficient to cause partial melting of the SCLM without any plume involvement. Specific features of the Umkondo LIP's plumbing system are supportive of either model, and an approach of multiple working hypotheses is recommended.
Showing items related by title, author, creator and subject.
Basement control on dyke distribution in Large Igneous Provinces: Case study of the Karoo triple junction.Jourdan, Fred; Feraud, G.; Bertrand, H.; Watkeys, M.; Kampunzu, A.; LeGall, B. (2006)Continental flood basalts consist of vast quantities of lava, sills and giant dyke swarms that are associated with continental break-up. The commonly radiating geometry of dyke swarms in these provinces is generally ...
Some causes and consequences of lithospheric thinning in the eastern North China Craton : evidence from latest Yanshanian granitoids and dykesGoss, Sarah Catherine (2010)The lithosphere beneath the eastern part of the North China Craton (NCC) is known to have been thick (> 200 km) during the Early Palaeozoic as manifested by the presence of diamondiferous kimberlites (Menzies et al., 1993; ...
Wang, Xuan-Ce; Li, Zheng-Xiang; Li, J.; Pisarevskiy, Sergei; Wingate, Michael (2014)The 1.21 Ga Marnda Moorn large igneous province (LIP) of the Yilgarn Craton is important for understanding the final breakup of the Nuna (Columbia) supercontinent. However, its petrogenesis is poorly understood owing to ...