Archaean and Proterozoic diamond growth from contrasting styles of large-scale magmatism

Janne M. Koornneef*, Michael U. Gress, Ingrid L. Chinn, Hielke A. Jelsma, Jeff W. Harris, Gareth R. Davies

*Corresponding author for this work

Research output: Contribution to JournalArticleAcademicpeer-review

Abstract

Precise dating of diamond growth is required to understand the interior workings of the early Earth and the deep carbon cycle. Here we report Sm-Nd isotope data from 26 individual garnet inclusions from 26 harzburgitic diamonds from Venetia, South Africa. Garnet inclusions and host diamonds comprise two compositional suites formed under markedly different conditions and define two isochrons, one Archaean (2.95 Ga) and one Proterozoic (1.15 Ga). The Archaean diamond suite formed from relatively cool fluid-dominated metasomatism during rifting of the southern shelf of the Zimbabwe Craton. The 1.8 billion years younger Proterozoic diamond suite formed by melt-dominated metasomatism related to the 1.1 Ga Umkondo Large Igneous Province. The results demonstrate that resolving the time of diamond growth events requires dating of individual inclusions, and that there was a major change in the magmatic processes responsible for harzburgitic diamond formation beneath Venetia from the Archaean to the Proterozoic.

Original languageEnglish
Article number648
JournalNature Communications
Volume8
Issue number1
DOIs
Publication statusPublished - 1 Dec 2017

Funding

The research leading to these results has received funding from the European Research Council under the European Union’s Seventh Framework Programme (FP7/2007-2013)/ ERC grant agreement no. 319209. J.M.K. received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No 654208 (Europlanet 2020 RI). J.W.H. thanks the Diamond Trading Company (a member of the De Beers Group of Companies) for the donation of the diamonds used in this study. We thank Richard Smeets, Bas van de Wagt and Sergei Matveev for support in the VU and UU laboratories and Suzette Timmerman for data discussion.

FundersFunder number
Horizon 2020 Framework Programme
Seventh Framework Programme319209, 871149, 654208
European Research Council

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