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Based on a brief introduction of the spatial distribution, rock types and formation ages of the late Mesoarchean–early Neoarchean (2.6~3.0 Ga) rocks in some key areas of the North China Craton, this paper summarizes the ages and geochemical and Nd-Hf-O isotopic compositions of the granitoids all over the craton. The late Mesoarchean–early Neoarchean basement shows the following features: (1) The late Mesoarchean–early Neoarchean magmatism is almost continuous, with a peak period of 2.70~2.75 Ga; (2) The late Mesoarchean–early Neoarchean rocks widely occur in the North China Craton, mainly in the Eastern Ancient Terrane, the Central Ancient Terrane and the Southern Ancient Terrane; (3) The intrusive rocks are mainly tonalite in composition, with trondhjemite, granodiorite, K-rich granite and gabbro-diorite; (4) The supracrustal rocks are commonly small in scale and scatter in granitoids. The rock types are mainly meta-basaltic rocks. In some areas, there are meta-komatiites, meta-andesitic-dacitic rocks and meta-clastic sedimentary rocks; (5) 2.6 Ga can be regarded as the boundary between the early and late Neoarchean in the North China Craton; (6) TTG rocks show large Sr/Y and La/Yb variations, plotting in the high-, medium- and low-pressure TTG areas in the Sr/Y–Y and La/Yb–Yb diagrams. Except for a few K-rich granites, the late Mesoarchean–early Neoarchean rocks are commonly depleted in Nd-Hf isotope compositions, with the magmatic zircon being similar in O isotope composition to that of the Archean magmatic zircon worldwide; (7) Many regions have similar geological characteristics, but some regions show great uniqueness. The research futher supports the understanding that, similar to many other typical cratons worldwide, the late Mesoarchean–early Neoarchean is the most important period of continental accretion in the North China Craton, and the main difference is that the North China Craton underwent a strong and widespread magmato-tectonothermal event at the end of the Neoarchean.

The recycling of supracrustal materials, and in particular hydrated rocks, has a profound impact on mantle composition and thus on the formation of continental crust, because water modifies the physical properties of lithological systems and the mechanisms of partial melting and fractional fractionation. On the modern Earth, plate tectonics offers an efficient mechanism for mass transport from the Earth's surface to its interior, but how far this mechanism dates back in the Earth's history is still uncertain. Here, we use zircon oxygen (O) isotopes to track recycling of supracrustal materials into the magma sources of early Archean igneous suites from the Kaapvaal Craton, southern Africa. The mean δ 18O values of zircon from TTG (tonalite–trondhjemite–granodiorite) rocks abruptly increase at the Paleo-Mesoarchean boundary (ca. 3230 million years ago; Ma), from mantle zircon values of 5‰–6‰ to approaching 7.1‰, and this increase occurs in ≤3230 Ma rocks with elevated Dy/Yb ratios. The 18O enrichment is a unique signature of low-temperature water–rock interaction on the Earth's surface. Because the later phase was emplaced into the same crustal level as the older one and TTG magmas would derive from melting processes in the garnet stability field (>40 km depth), we suggest that this evident shift in TTG zircon O isotopic compositions records the onset of recycling of the mafic oceanic crust that underwent seawater hydrothermal alteration at low temperature. The onset of the enhanced recycling of supracrustal materials may also have developed elsewhere in other Archean cratons and reflects a significant change in the tectonic realm during craton formation and stabilization, which may be important processes for the operation of plate tectonics on early Earth. [ABSTRACT FROM AUTHOR]