Work

Water in kimberlitic olivine provides insights into kimberlite ascent and diamond transport

Year: 2026

Type: article

Abstract: Kimberlites are volatile-rich magmas that transport diamonds from the deep lithosphere to the surface, yet the exact processes controlling their variable diamond abundances remain debated. Compiled dataset of water contents in mantle olivine shows that kimberlites containing water-rich (>40 wt. ppm) olivine exhibit higher diamond grades. Diffusion modeling coupled with estimates of the ascent velocities of olivine xenocrysts indicate that preserved water in the cores of olivine crystals reflects variable magma ascent rates. High water contents are indicative of rapid ascent that not only limits hydrogen loss but also leads to enhanced diamond transport. Conversely, slower ascent promotes olivine dehydration and reduction in diamond-carrying capacity. The link between olivine water content and diamond grade highlights that ascent rate is a key factor in controlling the varied diamond abundance in kimberlites. Water in olivine thus provides an additional, complementary, and cost-effective proxy for estimating kimberlite ascent and diamond-carrying efficiency. This study links higher diamond grades in kimberlites to water-rich olivine. Modeling suggests that rapid magma ascent preserves higher olivine water contents and facilitates efficient diamond transport, highlighting ascent rate as a key control on diamond preservation.

Source: Nature Communications

DOI: 10.1038/s41467-026-78870-6

Authors: Soumendu Sarkar, Rondi M. Davies, Qiwei Zhang, Luísa D. V. Carvalho, Thomas Stachel, D. Graham Pearson