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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

Författare

  • 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
Visa allt

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.

Avdelning/ar

  • Berggrundsgeologi

Publiceringsår

2014

Språk

Engelska

Sidor

129-143

Publikation/Tidskrift/Serie

Precambrian Research

Volym

249

Dokumenttyp

Artikel i tidskrift

Förlag

Elsevier

Ämne

  • Geology

Nyckelord

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

Status

Published

ISBN/ISSN/Övrigt

  • ISSN: 0301-9268