The continental lower crust

The lower crust, linking the lithospheric mantle and the upper crust, is the most active place of energy exchange between the crust and the mantle; and partial melting of the lower crust and upper mantle, and delamination of the lower crust can directly lead to crust/mantle material exchange, re-cycling, recombination. In other words, the lower crust is one of the most important site for mantle-crust interactions where magma underplating, ana texis, delamination, high-grade metamorphism, and other processes take place. However, the lower crust has been largely overlooked by previous studies of the deep Earth. In this paper, the lower crustal profile of the North China Craton is described in detail. On this basis, the craton-type lower crust processes are discussed, and their dynamic significance and important position in the study of continental dynamics are emphasized. Cratonization is the transition of the formerly chaotic crust of the continent to stable upper and lower crust, and thus establishing a stable lithosphere. This unprecedented stable relationship between the crust and the mantle has been maintained from the beginning to the present, and is the basis for continental evolution, ocean-continent interaction, and crust-mantle interaction. The cratonic crust is not static after formation, and the continental boundaries can change during ocean-continental subduction-collisions. Especially during continent-continent collisions, the continental crust that can form different continental blocks is superimposed, thickened, collapsed, disassembled, underpinned and re-stabilized. At the root of the continental orogenic belt, a new lower crust is formed to become the lower crust of the orogenic belt type. We, therefore, suggest in this paper that the craton-type lower crust processes should receive full attention in the study of the deep Earth as well as in the designing of geoscience curricula. © 2024 Science Frontiers editorial department. All rights reserved.