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Ulf Söderlund

Ulf Söderlund

Professor

Ulf Söderlund

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

Author

  • Michiel O. de Kocka
  • Richard Ernst
  • Ulf Söderlund
  • Fred Jourdan
  • Axel Hofmann
  • Bernard Le Gall
  • Herve Bertrand
  • Benny C. Chisonga
  • Nicolas Beukes
  • H. M. Rajesh
  • L. M. Moseki
  • R. Fuchs
Show all

Summary, in English

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.

Department/s

  • Lithosphere and Biosphere Science

Publishing year

2014

Language

English

Pages

129-143

Publication/Series

Precambrian Research

Volume

249

Document type

Journal article

Publisher

Elsevier

Topic

  • Geology

Keywords

  • Mesoproterozoic
  • Large Igneous Province
  • Geochronology
  • Rodinia
  • Kalahari craton
  • Dyke swarms

Status

Published

ISBN/ISSN/Other

  • ISSN: 0301-9268