Coupled sulfur-silicon isotopes reveal supracrustal origin of Archean continents

The genesis of Archean continental crust through partial melting of hydrous mafic protolith is widely acknowledged, yet the origin of the mafic protolith remains highly contentious. Silicon isotopes and quadruple sulfur isotopes serve as particularly powerful tools in this regard, as they directly trace the source nature of the felsic continent. Here, we integrate whole-rock silicon and sulfur isotopic data of Neoarchean granitoids from the North China Craton to constrain the origin and pathway of their protoliths. These granitoids exhibit non-zero Δ³³S (0.01‰ to − 0.24‰) and elevated δ³⁰Si ( − 0.09‰ to −0.05‰), requiring a supracrustal source and contrasting with the previously reported mantle-like zircon δ18O. Global compilation shows that granitoids formed after 3800 Ma uniformly contain enriched δ³⁰Si and non-zero Δ³³S, implying that most, if not all Archean continental crusts were derived from partial melting of supracrustal sources rather than unaltered mafic cumulates. Coupled sulfur and silicon isotopes in ancient granitoids reveal that early continental crust was generated by melting altered oceanic crust, recycled in the planet’s interior, rather than crystallising directly from pristine deep-mantle magma