Helium in diamonds unravels over a billion years of craton metasomatism

Weiss, Y., Kiro, Y., Class, C., Winckler, G., Harris, J. W. and Goldstein, S. L. (2021) Helium in diamonds unravels over a billion years of craton metasomatism. Nature Communications, 12, 2667. (doi: 10.1038/s41467-021-22860-3) (PMID:33976163) (PMCID:PMC8113505)

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Chemical events involving deep carbon- and water-rich fluids impact the continental lithosphere over its history. Diamonds are a by-product of such episodic fluid infiltrations, and entrapment of these fluids as microinclusions in lithospheric diamonds provide unique opportunities to investigate their nature. However, until now, direct constraints on the timing of such events have not been available. Here we report three alteration events in the southwest Kaapvaal lithosphere using U-Th-He geochronology of fluid-bearing diamonds, and constrain the upper limit of He diffusivity (to D ≈ 1.8 × 10−19 cm2 s−1), thus providing a means to directly place both upper and lower age limits on these alteration episodes. The youngest, during the Cretaceous, involved highly saline fluids, indicating a relationship with late-Mesozoic kimberlite eruptions. Remnants of two preceding events, by a Paleozoic silicic fluid and a Proterozoic carbonatitic fluid, are also encapsulated in Kaapvaal diamonds and are likely coeval with major surface tectonic events (e.g. the Damara and Namaqua–Natal orogenies).

Item Type:Articles
Additional Information:Y.W. acknowledges ISF Grant No. 2015/18; Y.W., S.L.G., C.C., G.W., and Y.K. acknowledge support by NSF Grants EAR-1348045 and EAR-1725323. S.L.G. acknowledges support from the Storke Endowment of the Department of Earth and Environmental Sciences of Columbia University.
Glasgow Author(s) Enlighten ID:Harris, Dr Jeff
Authors: Weiss, Y., Kiro, Y., Class, C., Winckler, G., Harris, J. W., and Goldstein, S. L.
College/School:College of Science and Engineering > School of Geographical and Earth Sciences
Journal Name:Nature Communications
Publisher:Nature Research
ISSN (Online):2041-1723
Copyright Holders:Copyright © 2021 The Authors
First Published:First published in Nature Communications 12: 2667
Publisher Policy:Reproduced under a Creative Commons License

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