Detrital zircon constraints on tectonic evolution of the Liaodong Paleoproterozoic orogenic belt, North China Craton

Abstract

The Liaodong Paleoproterozoic orogenic belt (LPOB), as part of the eastern North China Craton (NCC), is the result of global collision during the amalgamation of the Columbia supercontinent. Tectonics of the LPOB thus becomes the key to the understanding of the tectonic evolution of the NCC, and may provide important information on the assembly of the supercontinent. Detailed geochronological and geochemical analysis on detrital zircons from the Liaohe group is conducted to unravel the tectonic attribute of the major constituent, i.e., the Liaohe group within the LPOB. The results show that the U-Pb ages of detrital zircons from the Langzishan, Li’eryu, Gaojiayu and Dashiqiao formations at the middle-lower parts of the Liaohe group are mainly characterized by peaks at ~ 2500 and 2200–2100 Ma. However, the ages of detrital zircons from the Gaixian formation at the upper part are peaked at 2100–2000 Ma. The age data indicate that the Archean basement rocks and Paleoproterozoic magmatic activities at 2200–2100 Ma variably provide sources for sediments of the middle-lower Liaohe group. However, sediments of the Gaxian formation at the upper part of the Liaohe group are mainly derived from magmatic activities from the Nangrim and North Gyeonggi blocks at 2100–2000 Ma . The source characteristics of the Liaohe group highlight the importance of back-arc extension in the evolution of the LPOB. The tectonic evolution of the LPOB is, therefore, subdivided into four stages, i.e. early back-arc extension stage (2200–2080 Ma), transitional stage (2080–1940 Ma), main orogenic deformation (1940–1840 Ma) and post-orogenic plutonic emplacement (after 1840 Ma).