Paleoarchean deep crustal hydration and oxidation induced by subduction-driven water recycling
- Di Zhou
- Rongfeng Ge
- Simon A. Wilde
- William J. Collins
- Anthony I. S. Kemp
- Dongyang Lian
- Pengjie Cai
- Xiaolei Wang
2026-05-12
The formation of Earth’s early continental crust remains debated, with subduction and nonsubduction models offering competing explanations. Although Archean granitoids are known to originate from hydrous and oxidizing magmas, the mechanism for generating such magmas remains unclear. Here, we provide quantitative constraints on magmatic oxygen fugacity ( f O 2 ) and water content (H 2 O) for Paleoarchean granitoids from the East Pilbara Terrane, a key locality for nonsubduction crust formation models. Our data reveal systematic increases in f O 2 (from −0.9 to +1.4 log unit relative to the fayalite-magnetite-quartz buffer) and H 2 O (from 3.5 to 9.5 weight %) during 3.5 to 3.2 billion years ago. Thermodynamic-geochemical modeling shows that these magmas formed by water-fluxed melting of progressively enriched and oxidized mafic sources at similar pressures (0.9 to 1.3 gigapascals). Such extensive, secular deep crustal hydration and oxidation cannot be adequately explained by nonsubduction models. Instead, our findings underscore the indispensable role of subduction-driven water recycling in the origin of continental crust.