Sulfide-rich continental roots at cratonic margins formed by carbonated melts

Chunfei Chen; Michael W Förster; Svyatoslav S Shcheka; Isra S Ezad; Joshua J Shea; Yongsheng Liu; Dorrit E Jacob; Stephen F Foley

doi:10.1038/s41586-024-08316-w

Sulfide-rich continental roots at cratonic margins formed by carbonated melts

Nature. 2025 Jan 8. doi: 10.1038/s41586-024-08316-w. Online ahead of print.

Authors

Chunfei Chen¹, Michael W Förster^{2

3}, Svyatoslav S Shcheka², Isra S Ezad⁴, Joshua J Shea^{2

5}, Yongsheng Liu^{6

7}, Dorrit E Jacob³, Stephen F Foley^{2

3}

Affiliations

¹ State Key Laboratory of Geological Processes and Mineral Resources, School of Earth Sciences, China University of Geosciences, Wuhan, China. [email protected].
² School of Natural Sciences, Macquarie University, North Ryde, New South Wales, Australia.
³ Research School of Earth Sciences, Australian National University, Canberra, Australian Capital Territory, Australia.
⁴ Centre for Exploration Targeting, School of Earth Sciences, The university of Western Australia, Perth, Australia.
⁵ Department of Earth Sciences, University of Cambridge, Cambridge, UK.
⁶ State Key Laboratory of Geological Processes and Mineral Resources, School of Earth Sciences, China University of Geosciences, Wuhan, China.
⁷ Yangtze University, Jingzhou, China.

PMID: 39779858
DOI: 10.1038/s41586-024-08316-w

Abstract

The cratonic crust contains abundant mineral deposits of metals such as gold, copper and rare earths^1-5 and is underlain by a thick mantle lithosphere rich in the volatiles carbon, sulfur and water^6-8. Although volatiles are known to be key components in metallogenesis⁹, how and where they are distributed in the cratonic lithosphere mantle and their role in the initial enrichment of metals have not been sufficiently explored. Here we compile sulfur and copper contents of global cratonic peridotites, identifying sulfide-rich and copper-rich continental roots at depths of 160-190 km at cratonic margins. Our new high-pressure experiments show that carbonated silicate melts originating from the asthenosphere lose silicate components during reaction with lithospheric peridotite, evolving to carbonatite melts that become concentrated at cratonic margins. Sulfur solubility in melts substantially decreases as the SiO₂ content of melts decreases during this process, forcing sulfide precipitation and the formation of sulfide-rich continental roots at the base of the mantle lithosphere. The migration of carbonated melts towards cratonic margins replenishes the continental roots there with sulfur, explaining the co-location of magmatic metal deposits with carbonatites close to cratonic margins. These findings highlight the notable role of carbonated melts in metallogenesis and provide a potential platform for metal ore exploration.