Lightning-induced beads, ‘fulguroids’, associated with kimberlite eruptions in the Kalahari, Botswana

Abstract

Glassy beads were found in the sand cover associated with known and suspected kimberlites on the Kalahari plateau, Botswana. Morphology and chemistry were examined by ESEM and EDAX. The polymetallic and quartzose “beads”, here described for the first time and termed fulguroids, formed at very high temperatures, well in excess of those reached by the kimberlites. They solidified in free fall. We propose that they were melted in the atmosphere by lightning strikes on Kalahari overburden entrained when the kimberlites erupted.

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Acknowledgements

This research did not receive any specific grants from funding agencies in the public, commercial, or not-for-profit sectors. We thank African Queen Mines, Petra and Sekaka Diamonds and Gem Diamonds for providing access to cores for sampling. We are grateful to Alexander Shaw and an unknown reviewer for very constructive comments.

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Correspondence to M. J. McFarlane.

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McFarlane, M.J., Long, C.W. & Coetzee, S.H. Lightning-induced beads, ‘fulguroids’, associated with kimberlite eruptions in the Kalahari, Botswana. Int J Earth Sci (Geol Rundsch) 107, 2627–2633 (2018). https://doi.org/10.1007/s00531-018-1618-6

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Keywords

  • Kimberlites
  • Kalahari overburden
  • Lightning
  • Glassy beads
  • Fulguroids