Abstract:

The crescent-shaped Beiling syncline is a main structural feature in Zhoukoudian, Beijing, reflecting a very special structural deformation. Originally, it was only the superimposition of a Late Paleozoic continental basin and a Jurassic continental basin, which responded to the tectonic evolution of the North China Plate, but then it experienced the Yanshan Period fold deformation due to the local stress field produced by the Fangshan granodiorite emplacement. The formation process of the syncline is different from what is told about either fold mechanism or tectonic superimposition in general textbooks. This syncline actually occurred in a complicated system which involved deposition, deformation, magmatism, and metamorphism. Therefore, its origin can be better understood only through the thinking line of system theory, that is, by seeing local and seemingly unrelated structural details as parts of a system.

Key words: Beiling syncline, synthetical analyses of tectonic system, superimposed basin, rotation-shear structure, flat beam bending, Fangshan, Beijing