Huge growth of the late Mesoarchean–early Neoarchean (2.6~3.0 Ga) continental crust in the North China Craton: A review

Abstract

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.

Keywords

• late mesoarchean–early neoarchean
• north china craton
• nd–hf–o isotopes
• ttg
• huge continental growth