Global-scale continental thickening and emergence during the Paleoarchean

The emergence of continental crust fundamentally shaped Earth’s surface environment by modulating global climate and supplying nutrients to the oceans. However, the timing and extent of this emergence remain highly debated, between a postulated widespread event at ca. 2.5 Ga and earlier, localized occurrences evidenced by Paleoarchean shallow-marine sediments. We analyzed the Caozhuang supracrustal series, which represents the oldest shallow-marine sedimentary rocks preserved in the Eastern Ancient Domain (EAD) of the North China craton, and examined the timing and mechanism of the first large-scale continental emergence using isostatic calculations. Analyses of heavy minerals, whole-rock geochemistry, zircon morphology, and inclusions indicate that the dominant protolith of the Caozhuang quartzite was quartz sandstone with high maturity. Detrital zircon U-Pb-Hf and trace element data constrain its depositional age to the middle Paleoarchean (ca. 3.46 Ga). The crustal thickness inferred from the Eu/Eu* ratios of detrital zircons, combined with isostatic modeling, indicates that the EAD became subaerial at 3.50−3.43 Ga, consistent with an increase in the depth of partial melting of the Anshan tonalite-trondhjemite-granodiorite source rocks. A comparable sedimentary-magmatic evolution (involving shallow-marine sediments and potassic granites) also accompanied the middle to late Paleoarchean emergence of other cratons (Pilbara, Kaapvaal, and Singhbhum cratons). Therefore, we propose that the emergence of Earth’s earliest continents began during the middle to late Paleoarchean, initiating a profound transformation of Earth’s surface environment that set the stage for later climatic and biogeochemical evolution.