Modern arc-like water content in the source of 3.1-billion-year-old volcanic rocks

Vandenburg, Eric D., Nebel, Oliver, Smithies, R. Hugh, Cawood, Peter A., Miller, Laura A., Millet, Marc-Alban ORCID: https://orcid.org/0000-0003-2710-5374 and Capitanio, Fabio A. 2026. Modern arc-like water content in the source of 3.1-billion-year-old volcanic rocks. Nature Communications 17 (1) , 5630. 10.1038/s41467-026-74653-1

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Abstract

Whether Archean arc-like volcanism reflects subduction remains debated. We present high-resolution geochemical data from a well-preserved 3.13-3.10 Ga arc-like volcanic succession in Australia’s Pilbara Craton, a rare Archean analog of modern arc volcanism retaining fluid-mobile element concentrations consistent with primary magmatic values. The sequence records three primitive lava series typical of modern arcs: tholeiitic, calc-alkaline, and the oldest stratigraphically extensive genuine boninites. Geochemical modelling shows this melt diversity requires at least two mantle sources with distinct depletion histories. The mantle H2O required for fluid-assisted melting to produce these lavas substantially exceeds primitive mantle, approaching the H2O-saturated solidus of modern mantle wedges. We infer hydrous melting was triggered by dripduction, the short-lived inclined foundering of hydrated lithosphere without laterally continuous plate boundaries, in an off-plateau setting. Dripduction locally recycled surface water and generated arc-like magmas without self-sustained plate tectonics, possibly promoting mantle-ocean-atmosphere volatile exchange during the Archean.

Item Type:	Article
Date Type:	Published Online
Status:	Published
Schools:	Schools > Earth and Environmental Sciences
Publisher:	Nature Research
ISSN:	2041-1723
Date of First Compliant Deposit:	16 July 2026
Date of Acceptance:	11 June 2026
Last Modified:	16 Jul 2026 11:15
URI:	https://orca.cardiff.ac.uk/id/eprint/188270

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