Kinematics of the North China Block during Pangea Assembly and breakup in the Mantle Reference Frame and Their Implications for True Polar Wander

The North China Block (NCB), sandwitched between the Paleotethys and Paleo-Asian Ocean realms, played a pivotal role in the assembly and breakup of the Pangea supercontinent during the Paleozoic to Mesozoic. Yet the kinematic evolution of the NCB across the Pangea cycle—particularly its latitudinal drift, rotational behavior, and potential response to global-scale true polar wander (TPW)—remains debated due to data gaps in key intervals. We integrate new and published high-quality paleomagnetic data from the NCB spanning the Carboniferous to Jurassic to reconstruct its motion and assess TPW contributions. Our results show that the NCB resided at low paleolatitudes (～5–10°N) during the Late Carboniferous to the earliest Permian (～300 Ma), consistent with coeval equatorial faunal assemblages. Throughout the Permian, the NCB underwent persistent northward drift and clockwise rotation, culminating in the final closure of the Paleo-Asian Ocean by the Late Permian to Early Triassic. This trajectory aligns with the motion of Laurussia, indicating that the NCB had become an integral part of Pangea by the end of the Permian. In contrast, Early Jurassic volcanic rocks yield complex magnetization patterns with three distinct directional groups (shallow NW, moderate NE, and steep inclinations), suggesting either complicated response to the Jurassic Monstershift TPW event or multi-phase overprinting by regional tectonics. Critically, when compared with the apparent standstill of the adjacent Mongolia Block—which remained near ～30°N throughout the Carboniferous due to the counteraction between northward plate motion and southward TPW—the NCB’s steady northward migration provides a robust reference frame for isolating TPW signals in East Asia. We propose that the decoupled kinematics between the NCB and Mongolia during the Permo-Carboniferous reflects differential responses to the same TPW event, highlighting the necessity of multi-block analyses to disentangle plate tectonic motion from true polar wander in supercontinent cycles.

Keywords: North China Block; Pangea; Paleo-Asian Ocean; Paleomagnetism; True Polar Wander; Supercontinent cycle

Acknowledgments
This research is funded by the Natural Science Foundation of China (NSFC) (42372254), National Key R&D Program of China (2023YFF0803604, 2024YFF0808000)