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Rift-induced disruption of cratonic keels drives kimberlite volcanism

Rift-induced disruption of cratonic keels drives kimberlite volcanism
Rift-induced disruption of cratonic keels drives kimberlite volcanism

Kimberlites are volatile-rich, occasionally diamond-bearing magmas that have erupted explosively at Earth’s surface in the geologic past 1–3. These enigmatic magmas, originating from depths exceeding 150 km in Earth’s mantle 1, occur in stable cratons and in pulses broadly synchronous with supercontinent cyclicity 4. Whether their mobilization is driven by mantle plumes 5 or by mechanical weakening of cratonic lithosphere 4,6 remains unclear. Here we show that most kimberlites spanning the past billion years erupted about 30 million years (Myr) after continental breakup, suggesting an association with rifting processes. Our dynamical and analytical models show that physically steep lithosphere–asthenosphere boundaries (LABs) formed during rifting generate convective instabilities in the asthenosphere that slowly migrate many hundreds to thousands of kilometres inboard of rift zones. These instabilities endure many tens of millions of years after continental breakup and destabilize the basal tens of kilometres of the cratonic lithosphere, or keel. Displaced keel is replaced by a hot, upwelling mixture of asthenosphere and recycled volatile-rich keel in the return flow, causing decompressional partial melting. Our calculations show that this process can generate small-volume, low-degree, volatile-rich melts, closely matching the characteristics expected of kimberlites 1–3. Together, these results provide a quantitative and mechanistic link between kimberlite episodicity and supercontinent cycles through progressive disruption of cratonic keels.

0028-0836
344-350
Gernon, Thomas
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Jones, Stephen
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Brune, Sascha
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Hincks, Thea
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Palmer, Martin
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Schumacher, John
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Primiceri, Rebecca
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Field, Matthew
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Griffin, William
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O'Reilly, Suzanne
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Keir, Derek
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Spencer, Christopher
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Merdith, Andrew
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Glerum, Anne
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Gernon, Thomas
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Jones, Stephen
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Brune, Sascha
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Hincks, Thea
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Palmer, Martin
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Schumacher, John
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Primiceri, Rebecca
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Field, Matthew
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Griffin, William
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O'Reilly, Suzanne
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Keir, Derek
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Spencer, Christopher
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Merdith, Andrew
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Glerum, Anne
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Gernon, Thomas, Jones, Stephen, Brune, Sascha, Hincks, Thea, Palmer, Martin, Schumacher, John, Primiceri, Rebecca, Field, Matthew, Griffin, William, O'Reilly, Suzanne, Keir, Derek, Spencer, Christopher, Merdith, Andrew and Glerum, Anne (2023) Rift-induced disruption of cratonic keels drives kimberlite volcanism. Nature, 620 (7973), 344-350. (doi:10.1038/s41586-023-06193-3).

Record type: Article

Abstract

Kimberlites are volatile-rich, occasionally diamond-bearing magmas that have erupted explosively at Earth’s surface in the geologic past 1–3. These enigmatic magmas, originating from depths exceeding 150 km in Earth’s mantle 1, occur in stable cratons and in pulses broadly synchronous with supercontinent cyclicity 4. Whether their mobilization is driven by mantle plumes 5 or by mechanical weakening of cratonic lithosphere 4,6 remains unclear. Here we show that most kimberlites spanning the past billion years erupted about 30 million years (Myr) after continental breakup, suggesting an association with rifting processes. Our dynamical and analytical models show that physically steep lithosphere–asthenosphere boundaries (LABs) formed during rifting generate convective instabilities in the asthenosphere that slowly migrate many hundreds to thousands of kilometres inboard of rift zones. These instabilities endure many tens of millions of years after continental breakup and destabilize the basal tens of kilometres of the cratonic lithosphere, or keel. Displaced keel is replaced by a hot, upwelling mixture of asthenosphere and recycled volatile-rich keel in the return flow, causing decompressional partial melting. Our calculations show that this process can generate small-volume, low-degree, volatile-rich melts, closely matching the characteristics expected of kimberlites 1–3. Together, these results provide a quantitative and mechanistic link between kimberlite episodicity and supercontinent cycles through progressive disruption of cratonic keels.

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Accepted/In Press date: 10 May 2023
e-pub ahead of print date: 26 July 2023
Published date: 10 August 2023
Additional Information: Funding Information: T.M.G. and T.K.H. were supported by The Alan Turing Institute under the EPSRC grant EP/N510129/1. T.M.G. gratefully acknowledges funding from the WoodNext Foundation, a component fund administered by the Greater Houston Community Foundation. T.M.G. and R.M.P. received support from the Web Science Institute Stimulus Fund. A.S.M. was supported by the MCSA Fellowship NEOEARTH, project 893615. W.L.G. and S.Y.O. acknowledge funds from Australian Research Council grant CE110001017 and AuScope NCRIS. This is contribution 1736 from the ARC Centre of Excellence for Core to Crust Fluid Systems (http://www.ccfs.mq.edu.au) and 1505 in the GEMOC ARC National Key Centre (http://www.gemoc.mq.edu.au). The authors gratefully acknowledge the computing time granted by the Resource Allocation Board and provided on the supercomputer Lise at NHR@ZIB as part of the NHR infrastructure. The calculations for this research were conducted with computing resources under the project bbp00039. We thank J. VanDecar for his invaluable editorial support. We are very grateful to S. Tappe for providing the kimberlite database from ref. 6. We also appreciate helpful discussions with R. Huismans, S. Sparks, Z. Pintér, R. N. Mitchell and L. T. de Oliveira. T.M.G. would like to acknowledge the kimberlite research community for many lively and thought-provoking interactions over the past two decades. T.M.G. also wishes to acknowledge and pay tribute to the late M. de Wit, whose visionary and inspiring leadership on geodynamics and the evolution of the Gondwana supercontinent has left an indelible mark on this field. Maarten’s contributions will always be remembered and appreciated. Funding Information: T.M.G. and T.K.H. were supported by The Alan Turing Institute under the EPSRC grant EP/N510129/1. T.M.G. gratefully acknowledges funding from the WoodNext Foundation, a component fund administered by the Greater Houston Community Foundation. T.M.G. and R.M.P. received support from the Web Science Institute Stimulus Fund. A.S.M. was supported by the MCSA Fellowship NEOEARTH, project 893615. W.L.G. and S.Y.O. acknowledge funds from Australian Research Council grant CE110001017 and AuScope NCRIS. This is contribution 1736 from the ARC Centre of Excellence for Core to Crust Fluid Systems ( http://www.ccfs.mq.edu.au ) and 1505 in the GEMOC ARC National Key Centre ( http://www.gemoc.mq.edu.au ). The authors gratefully acknowledge the computing time granted by the Resource Allocation Board and provided on the supercomputer Lise at NHR@ZIB as part of the NHR infrastructure. The calculations for this research were conducted with computing resources under the project bbp00039. We thank J. VanDecar for his invaluable editorial support. We are very grateful to S. Tappe for providing the kimberlite database from ref. . We also appreciate helpful discussions with R. Huismans, S. Sparks, Z. Pintér, R. N. Mitchell and L. T. de Oliveira. T.M.G. would like to acknowledge the kimberlite research community for many lively and thought-provoking interactions over the past two decades. T.M.G. also wishes to acknowledge and pay tribute to the late M. de Wit, whose visionary and inspiring leadership on geodynamics and the evolution of the Gondwana supercontinent has left an indelible mark on this field. Maarten’s contributions will always be remembered and appreciated. Publisher Copyright: © 2023, The Author(s), under exclusive licence to Springer Nature Limited.

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Local EPrints ID: 477311
URI: http://eprints.soton.ac.uk/id/eprint/477311
ISSN: 0028-0836
PURE UUID: d3f3b428-971b-4b3b-930b-04beea719255
ORCID for Thomas Gernon: ORCID iD orcid.org/0000-0002-7717-2092
ORCID for Thea Hincks: ORCID iD orcid.org/0000-0003-4537-6194
ORCID for Derek Keir: ORCID iD orcid.org/0000-0001-8787-8446

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Date deposited: 02 Jun 2023 17:14
Last modified: 17 Mar 2024 07:45

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Contributors

Author: Thomas Gernon ORCID iD
Author: Stephen Jones
Author: Sascha Brune
Author: Thea Hincks ORCID iD
Author: Martin Palmer
Author: John Schumacher
Author: Rebecca Primiceri
Author: Matthew Field
Author: William Griffin
Author: Suzanne O'Reilly
Author: Derek Keir ORCID iD
Author: Christopher Spencer
Author: Andrew Merdith
Author: Anne Glerum

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