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Dykes of the 1.11 Ga Umkondo LIP, Southern Africa: Clues to a complex plumbing system

de Kocka, Michiel O.; Ernst, Richard; Söderlund, Ulf LU ; Jourdan, Fred; Hofmann, Axel; Le Gall, Bernard; Bertrand, Herve; Chisonga, Benny C.; Beukes, Nicolas and Rajesh, H. M., et al. (2014) In Precambrian Research 249. p.129-143
Abstract
The Umkondo Large Igneous Province (LIP) is represented by widespread (similar to 2.0 x 10(6) km(2)) 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 similar to 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... (More)
The Umkondo Large Igneous Province (LIP) is represented by widespread (similar to 2.0 x 10(6) km(2)) 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 similar to 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. (C) 2014 Elsevier B.V. All rights reserved. (Less)
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keywords
Mesoproterozoic, Large Igneous Province, Geochronology, Rodinia, Kalahari craton, Dyke swarms
in
Precambrian Research
volume
249
pages
129 - 143
publisher
Elsevier
external identifiers
  • wos:000339038100009
  • scopus:84901814297
ISSN
0301-9268
DOI
10.1016/j.precamres.2014.05.006
language
English
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yes
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ee9f084f-3313-4dfa-91b3-b3d133b5a536 (old id 4591894)
date added to LUP
2014-09-08 08:35:48
date last changed
2017-11-19 03:23:29
@article{ee9f084f-3313-4dfa-91b3-b3d133b5a536,
  abstract     = {The Umkondo Large Igneous Province (LIP) is represented by widespread (similar to 2.0 x 10(6) km(2)) 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 similar to 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. (C) 2014 Elsevier B.V. All rights reserved.},
  author       = {de Kocka, Michiel O. and Ernst, Richard and Söderlund, Ulf and Jourdan, Fred and Hofmann, Axel and Le Gall, Bernard and Bertrand, Herve and Chisonga, Benny C. and Beukes, Nicolas and Rajesh, H. M. and Moseki, L. M. and Fuchs, R.},
  issn         = {0301-9268},
  keyword      = {Mesoproterozoic,Large Igneous Province,Geochronology,Rodinia,Kalahari craton,Dyke swarms},
  language     = {eng},
  pages        = {129--143},
  publisher    = {Elsevier},
  series       = {Precambrian Research},
  title        = {Dykes of the 1.11 Ga Umkondo LIP, Southern Africa: Clues to a complex plumbing system},
  url          = {http://dx.doi.org/10.1016/j.precamres.2014.05.006},
  volume       = {249},
  year         = {2014},
}