Influence of subduction dynamics on Mesozoic magmatic tempos in the North China Craton

Temporal variations in magmatism are crucial for understanding the processes that drive continental evolution. This study examines the Mesozoic volcanic rocks from the North China Craton, specifically from the western Beijing region of China, to explore the mechanisms behind magmatic rhythms in a flat slab subduction setting. New geochemical data from volcanic rocks of the Nandaling (175−167 Ma), Tiaojishan (158−149 Ma), and Zhangjiakou (137−130 Ma) formations reveal a compositional shift from mafic to felsic over time. The Nandaling Formation is dominated by basalts, the Tiaojishan Formation consists mainly of andesites with minor mafic and felsic components, and the Zhangjiakou Formation is characterized by trachydacites and rhyolites. These variations reflect a temporal shift in magmatic sources, evolving from an Early−Middle Jurassic subcontinental lithospheric mantle origin, to mixed lithospheric mantle and lower-crustal components in the Middle−Late Jurassic, and ultimately to a predominantly lower-crustal source by the Early Cretaceous. These shifts in magmatic source are closely associated with phases of flat slab subduction followed by rollback of the Paleo-Pacific plate, which induced significant lithospheric thinning. Our findings highlight the critical role of subduction dynamics and lithospheric processes in shaping episodic magmatism. The temporal evolution of these volcanic rocks provides key insights into the interaction between tectonic forces and magmatic activity, thereby advancing our understanding of continental lithospheric evolution.