Kimberlite genesis from a common carbonate-rich primary melt modified by lithospheric mantle assimilation

Andrea Giuliani*, D. Graham Pearson, Ashton Soltys, Hayden Dalton, David Phillips, Stephen F. Foley, Emilie Lim, Karsten Goemann, William L. Griffin, Roger H. Mitchell

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

13 Citations (Scopus)

Abstract

Quantifying the compositional evolution of mantle-derived melts from source to surface is fundamental for constraining the nature of primary melts and deep Earth composition. Despite abundant evidence for interaction between carbonate-rich melts, including diamondiferous kimberlites, and mantle wall rocks en route to surface, the effects of this interaction on melt compositions are poorly constrained. Here, we demonstrate a robust linear correlation between the Mg/Si ratios of kimberlites and their entrained mantle components and between Mg/Fe ratios of mantle-derived olivine cores and magmatic olivine rims in kimberlites worldwide. Combined with numerical modeling, these findings indicate that kimberlite melts with highly variable composition were broadly similar before lithosphere assimilation. This implies that kimberlites worldwide originated by partial melting of compositionally similar convective mantle sources under comparable physical conditions. We conclude that mantle assimilation markedly alters the major element composition of carbonate-rich melts and is a major process in the evolution of mantle-derived magmas.

Original languageEnglish
Article numbereaaz0424
Pages (from-to)1-9
Number of pages9
JournalScience Advances
Volume6
Issue number17
DOIs
Publication statusPublished - 24 Apr 2020

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