克拉通化与华北陆块的形成

Abstract

Cratonization is a key geological process to form stable continental masses with a considerable scale. The Precambrian global cratonization and formation of supercratons in the world is an unrepeated event in the history of the Earth's formation and evolution. Mainly based on study of early Precambrian geology in Eastern Hebei Region and combining other Archean regions in the North China Craton (NCC), the author proposes a two-stage cratonization model of the NCC. The first stage took place at the end of Neoarchean of ~2.5 Ga (boundary time between Archean and Proterozoic), when several micro-blocks were amalgamated together with amphibolite-granulite facies metamorphism and intrusion of crustal-melting granites to form the present-scale NCC. The second cratonization event is cratonic reworking, corresponding to rifting-subduction-collision at 2.3-1.97 Ga and subsequent extension-uplifting related to upwelling mantle at 1.97-1.82 Ga, which could be linked to, respectively, assembly and breaking up of the Columbia Supercontinent. Three main Paleoproterozoic mobile belts in the NCC record that small remnant Neoarchean ocean basins and continental rift basins within the craton were opened and finally closed, and metamorphosed to greenschist-amphibolite facies at ~2.0-1.97 Ga. After that, high-grade granulite facies (HT-HP and HT-UHT) metamorphism with abnormally high heat occurred at 1.97-1.82 Ga. A metamorphism-migmatization event that includes lower crust of the NCC uplifting as a whole, intrusion of mafic dyke swarms, continental rifting and anorogenic magmatic action took place in 1.82-1.65 Ga, marking that the second cratonization of the NCC was finally accomplished and started to evolve to a period of stable continent (platform). © 2011 Science China Press and Springer-Verlag Berlin Heidelberg.