Noble gases confirm plume related mantle degassing beneath Southern Africa

Stuart Gilfillan* (Corresponding Author), D Gyore, Gareth Johnson, Clare Elizabeth Bond, Nigel Hicks, Robert Lister, David Jones, Yannick Kremer, Stuart R. Haszeldine, Finlay M. Stuart

*Corresponding author for this work

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Abstract

Southern Africa is characterised by unusually elevated topography and abnormal heat flow. This can be explained by thermal perturbation of the mantle, but the origin of this is unclear. Geophysics has not detected a thermal anomaly in the upper mantle and there is no geochemical evidence of an asthenosphere mantle contribution to the Cenozoic volcanic record of the region. Here we show that natural CO2 seeps along the Ntlakwe-Bongwan fault within KwaZulu-Natal, South Africa, have C-He isotope systematics that support an origin from degassing mantle melts. Neon isotopes indicate that the melts originate from a deep mantle source that is similar to the mantle plume beneath Réunion, rather than the convecting upper mantle or sub-continental lithosphere. This confirms the existence of the Quathlamba mantle plume and importantly provides the first evidence in support of upwelling deep mantle beneath Southern Africa, helping to explain the regions elevation and abnormal heat flow.
Original languageEnglish
Article number5028
JournalNature Communications
Volume10
Early online date5 Nov 2019
DOIs
Publication statusPublished - 2019

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Keywords

  • geochemistry
  • geodynamics

Cite this

Gilfillan, S., Gyore, D., Johnson, G., Bond, C. E., Hicks, N., Lister, R., ... Stuart, F. M. (2019). Noble gases confirm plume related mantle degassing beneath Southern Africa. Nature Communications, 10, [5028]. https://doi.org/10.1038/s41467-019-12944-6