The browser you are using is not supported by this website. All versions of Internet Explorer are no longer supported, either by us or Microsoft (read more here: https://www.microsoft.com/en-us/microsoft-365/windows/end-of-ie-support).

Please use a modern browser to fully experience our website, such as the newest versions of Edge, Chrome, Firefox or Safari etc.

Ulf Söderlund

Ulf Söderlund

Professor

Ulf Söderlund

The Ahmeyim Great Dyke of Mauritania: A newly dated Archaean intrusion

Author

  • J. Tait
  • G. Straathof
  • Ulf Söderlund
  • R. E. Ernst
  • R. Key
  • S. M. Jowitt
  • K. Lo
  • M. E. M. Dahmada
  • O. N'Diaye

Summary, in English

A precise U-Pb baddeleyite age of 2733 +/- 2 Ma has been obtained for the Ahmeyim Great Dyke of Mauritania that intruded into the Tasiast-Tijirit Terrane of the Reguibat Shield, NW Mauritania. This dyke is approximately 1500 m wide at the sampling area and extends for more than 150 km NNE/SSW. Major and trace element geochemistry of the dyke indicates that the magmas that formed this intrusive body were sub-alkaline, tholeiitic and boninitic, and the presence of a negative Nb anomaly indicates the involvement of subducted oceanic lithosphere during magma genesis, most likely an inherited signature from earlier subduction events and the Mesoarchaean collision of the Tasiast-Tijirit and Choum-Rag el Abiod Terranes. A palaeomagnetic study was also undertaken on samples collected from two different sections across the dyke. However, no within- or inter-site grouping of any palaeomagnetic directions could be identified, thus precluding any palaeographic interpretation. The Ahmeyim Great Dyke is interpreted to be part of the feeder system for a 2733 Ma Large Igneous Province (LIP); tholeiitic-komatiitic greenstone belts of this age are absent in the West African Craton (WAC) but are present on many other blocks. However, additional constraints are required to reliably link the Ahmeyim Great Dyke with any other such LIP-type greenstone belts in late Archaean supercontinent reconstructions. The magmas that formed the Ahmeyim Great Dyke were boninitic; this, combined with evidence of crustal contamination, the scale of the dyke and its potential link (as a feeder) to greenstone belts of tholeiitic-komatiitic affiliation within other crustal blocks suggests that it, and cogenetic magmatic units elsewhere, may be prospective for magmatic Ni-Cu-PGE sulphide exploration. (C) 2012 Published by Elsevier B.V.

Department/s

  • Lithosphere and Biosphere Science

Publishing year

2013

Language

English

Pages

323-332

Publication/Series

Lithos

Volume

174

Document type

Journal article

Publisher

Elsevier

Topic

  • Geology

Keywords

  • Mauritania
  • Archaean
  • Precambrian
  • LIPs
  • West African Craton

Status

Published

ISBN/ISSN/Other

  • ISSN: 0024-4937