Is the association between PGE deposits and diamond provinces in ancient cratonic blocks linked to mantle overturns in the early earth?

Groves, David I., Maier, Wolfgang ORCID: https://orcid.org/0000-0002-8654-6658, Santosh, M., Zhang, Liang and Yang, Cheng-Xue 2026. Is the association between PGE deposits and diamond provinces in ancient cratonic blocks linked to mantle overturns in the early earth? Ore and Energy Resource Geology 21 , 100142. 10.1016/j.oreoa.2026.100142

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Abstract

Earth’s oldest cratons, diamond provinces, including some with CLIPPIR (Cullinan-like, Large, Inclusion-poor, Pure, Irregular, and Resorbed) diamonds, and PGE-rich mafic intrusions display a common spatial, although not temporal, relationship. These include, in broad order of combined value of diamonds and PGEs, the Kaapvaal Craton, Anabar Craton and adjacent Aldan Shield, Wyoming Craton, Kola Craton, North China Craton, and Zimbabwe Craton. The diamonds formed almost exclusively in the early Precambrian whereas the PGE-bearing bodies intruded during the Neoarchean to the Mesozoic. There is evidence that the Paleoproterozoic Bushveld Complex in the Kaapvaal Craton, at least, was formed from deep mantle or mantle plume-derived magma, as were the CLIPPIR diamonds. These and other deep diamonds and their fluid inclusions have stable isotope ratios with mixed mantle-crustal ratios, plus inclusions of Ni-Fe or Fe metal and Ni-Fe sulfides, some with Au or PGEs. Some of these are as old as 3.1 (possibly 3.5) Ga and hence predate Phanerozoic-style subduction-related tectonics. However, most models based on the diamonds relate the mixed mantle-crust signature to subduction-related recycling, and mantle inhomogeneities to slab stacking. Here an alternative model of one or more Paleoarchean-Mesoarchean mantle overturns is proposed that would also explain the mixed mantle-crust isotope signals and deep mantle heterogeneity. Potential evidence for involvement of metal-rich outer core is provided by Ni-Fe and Fe metal inclusions in diamonds. Involvement of core components recorded in mantle-plume-related Hawaiian ocean island basalts, and potentially in Eoarchean mantle, but evidence for core-related PGEs in layered intrusions, including the Bushveld Complex is at best equivocal. Potential evidence for components of core in early Earth rock sequences is the occurrence of a Ni-oxide deposit with anomalous concentrations of Pt, Pd, Rh, Ru, Os, Ir, and Au within a Paleoarchean sequence on the Kaapvaal Craton. It is concluded that CLIPPIR diamonds are best interpreted to be related to early Earth mantle overturns that contaminated the deep mantle with continental components, but that involvement of PGEs from the core or core-mantle boundary is still equivocal, despite evidence for the involvement of core in Eoarchean mantle overturns.

Item Type:	Article
Date Type:	Publication
Status:	Published
Schools:	Schools > Physical, Chemical & Environmental Sciences
ISSN:	2666-2612
Date of First Compliant Deposit:	1 September 2026
Last Modified:	01 Sep 2026 11:45
URI:	https://orca.cardiff.ac.uk/id/eprint/189298

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