Mercury isotopic turnover in 2.6–2.5 Ga granitoids: Evidence of oceanic subduction on late Neoarchean Earth

The geodynamic mechanism that shaped the growth and evolution of Neoarchean continental crust has always been controversial. Here, we employ mercury (Hg) isotopes to investigate the petrogenesis of 3.1–2.5 Ga granitoids from the North China Craton (NCC). Samples older than 2.6 Ga exhibit near-zero ∆¹⁹⁹Hg values (−0.1 to 0.1‰), consistent with derivation from primitive mantle or reworked Eo–Paleoarchean crust. In contrast, those emplaced at 2.6–2.5 Ga display bimodal Δ¹⁹⁹Hg signatures, reflecting dual mercury sources: primitive mantle (near-zero Δ¹⁹⁹Hg) and recycled marine Hg (positive Δ¹⁹⁹Hg). The ∆¹⁹⁹Hg turnover around 2.6–2.5 Ga reject meteorite-impact, heat-pipe, and sagduction models for late Neoarchean NCC evolution and instead support subduction-driven tectonics as the dominant mechanism for surface-material recycling and crustal growth.