The timeline of prolonged accretionary processes in eastern Central Asian Orogenic Belt: Insights from episodic Paleozoic intrusions in central Inner Mongolia, North China

Updating magmatic profile in crucial constituent terranes across the Central Asian Orogenic Belt presents a key to chronicling the timeline of prolonged accretionary processes and termination of the Paleo-Asian Ocean in the northern China-southern Mongolia tract. Here we performed a systematic geochronological and geochemical study on a spectrum of Paleozoic intrusions from the Erenhot region in central Inner Mongolia, North China, within the hinterland of the tract, with four distinct magmatic episodes unraveled. Combining these episodes with the previously documented events from contiguous regions defines two major tectono-magmatic cycles. The early Paleozoic cycle (500-450 Ma) evolved from initial fluid-fluxed tholeiitic and calc-alkaline granitoids to melt-fertilized mafic-intermediate magmatism. It appears to experience the initiation and maturation of a Western Pacifictype intra-oceanic arc system that culminated in ridge subduction. The late Paleozoic cycle expanded in magmatic expression from alkaline intermediate-felsic pulses through plate subduction through slab rollback and backarc rifting to ridge-trench collision and backarc basin closure. Featuring a Rodinia-aged terrane affinity and a representative Paleozoic magmatic profile, the Erenhot re-gion provides an optimal site for correlating the evolution of mosaic terranes in southern Mongolia and northern China, and for evalu-ating the coupled evolution of shifting tec-tonic regimes and plural crustal generation mechanisms within a retreating accretionary orogen.

Automated summary

Updating the magmatic profile in central Inner Mongolia, North China is crucial for understanding the timeline of accretionary processes and the termination of the Paleo-Asian Ocean. In this study, we conducted a geochronological and geochemical analysis of Paleozoic intrusions in the Erenhot region and identified four distinct magmatic episodes, which contribute to the definition of two major tectono-magmatic cycles. The early Paleozoic cycle (500-450 Ma) records the development of a Western Pacific-type intra-oceanic arc system, while the late Paleozoic cycle showcases the processes of plate subduction, slab rollback, and backarc rifting. The Erenhot region, with its Rodinia-aged terrane affinity and representative Paleozoic magmatic profile, provides an optimal site for studying the evolution of mosaic terranes in southern Mongolia and northern China.