Primordial neon and the deep mantle origin of kimberlites


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Date

2024-09-16

Publication Type

Working Paper

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yes

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Abstract

The genesis of kimberlites – Earth’s deepest-derived melts – remains an unresolved question despite the economic and scientific interest surrounding these diamond-bearing continental magmas. One critical question is whether they tap ancient, deep mantle or the shallow convecting mantle with partial melting triggered by deep-mantle plumes or plate tectonics. To address this question, we report the compositions of He-Ne-Ar isotopes, formidable tracers of the occurrence of primordial material in the mantle, in magmatic fluids trapped in olivine from kimberlites worldwide. We show that two kimberlites have Ne isotopes less nucleogenic than the upper mantle, which unequivocally requires a deep mantle origin. This is corroborated by previous evidence of negative W isotope anomalies and the location of these kimberlites along age-progressive hot-spot tracks. The lack of strong primordial He isotope signatures indicates overprinting by lithospheric and crustal components, which suggests that Ne isotopes are more robust tracers of deep-mantle contributions in intraplate magmas.

Publication status

published

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Pages / Article No.

Publisher

Research Square

Event

Edition / version

v1

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Organisational unit

03592 - Schmidt, Max / Schmidt, Max check_circle
03946 - Schönbächler, Maria / Schönbächler, Maria check_circle

Notes

This preprint is under consideration at a Nature Portfolio Journal.

Funding

180126 - A new understanding of kimberlite magmas from deep Earth to diamond mines (SNF)

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