Late Jurassic true polar event revealed by paleomagnetic study in the North China Craton and its implication for regional tectonics and biota evolution in East Asia

The reorientation of Earth through rotation of its solid shell relative to its spin axis is known as True polar wander (TPW). It is well-documented at present, but the occurrence of TPW in the geologic past remains controversial. This is especially so for Late Jurassic TPW, where the veracity and dynamics of a particularly large shift remain debated. Here, we report three palaeomagnetic poles at 153, 147, and 141 million years (Myr) ago from the North China craton that document an ~12° southward shift in palaeolatitude from 155–147 Myr ago (~1.5° Myr^-1), immediately followed by an ~10° northward displacement between 147–141 Myr ago (~1.6° Myr^-1). Our data support a large round-trip TPW oscillation in the past 200 Myr. By comparison of Jurassic paleomagnetic poles of the NCC and SIB, we suggest that the Late Jurassic true polar wander event may have biased paleomagnetic results and thereby affected the interpretation of the final closure of the Mongol-Okhotsk Ocean. Combining paleomagnetic data with regional geological evidence, we propose that the Mongol-Okhotsk Ocean was closed in its eastern segment in the Late Jurassic, marking the formation of the central Asian continent. We suggest that the shifting back-and-forth of the continents may contribute to the biota evolution in East Asia and the global Jurassic–Cretaceous extinction and endemism.