A discussion on lithosphere evolution of Yanshan tectonic cycle in Hebei- Beijing-Tianjin region

The lithospheric evolution of Hebei- Beijing- Tianjin region constitutes a complete tectonic evolution cycle. The lithosphere experienced multi- stage evolution, comprising tension cracking (non- orogenic) at the early stage of Late Triassic, stable transition at the late stage of Late Triassic (pre-orogenic), squeeze intraplate orogeny between the Early Jurassic and middle stage of Early Cretaceous (sym- orogenic), and stable transition during Cretaceous- Paleocene (post- orogenic). During the intraplate orogenic process of Yanshan tectonic cycle, the original cratonic lithosphere was strongly transformed and rebuilt, and formed a new orogenic lithosphere, which seems to have been the most important content of the Yanshan tectonic cycle and the substantive result of intraplate orogeny.