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

Michiel O. De Kock, Richard Ernst, Ulf Söderlund, Fred Jourdan, Axel Hofmann, Bernard Le Gall, Hervé Bertrand, Benny C. Chisonga, Nicolas Beukes, H. M. Rajesh, L. M. Moseki, R. Fuchs

Research output: Contribution to journalArticlepeer-review

35 Citations (Scopus)

Abstract

The Umkondo Large Igneous Province (LIP) is represented by widespread (~2.0×106km2) mafic intrusions that were rapidly emplaced (1112-1108Ma) 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 ~1110Ma 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.

Original languageEnglish
Pages (from-to)129-143
Number of pages15
JournalPrecambrian Research
Volume249
DOIs
Publication statusPublished - Jan 1 2014

All Science Journal Classification (ASJC) codes

  • Geology
  • Geochemistry and Petrology

Fingerprint Dive into the research topics of 'Dykes of the 1.11Ga Umkondo LIP, Southern Africa: Clues to a complex plumbing system'. Together they form a unique fingerprint.

Cite this