The Dynamic Mechanisms of Significantly Different Crustal Movements Within the Tibetan Plateau and Its Southeastern Edge in the Cenozoic

Abstract The Cenozoic crustal deformation characteristics and underlying mechanisms in the southeastern Tibetan Plateau (TP) are critical for constraining tectonic models of plateau growth during this era. Paleomagnetic analyses and U–Pb zircon dating were conducted on the syenite pluton and adjacent sandstones in the Jianchuan Basin (26°38′43″N, 99°49′18″E), located at the southeastern margin of the TP. The site‐mean direction obtained from syenite rocks is D = 7.1°, I = 42.9°, k = 88.6, α 95 = 7.2° at 35.54–33.14 Ma and the tilt‐corrected site‐mean direction obtained from the sandstones is D s = 17.5°, Is = 43.4°, k = 141.0, α 95 = 3.1° at 28.0–24.0 Ma. Combined with Cenozoic paleomagnetic data sets from regions surrounding the Eastern Himalayan Syntaxis (EHS), the results indicate that although clockwise rotational crustal deformation initiated at the southeastern margin of the TP around ∼28.0 Ma, no significant latitudinal displacement has occurred since then. In contrast, the central and southeastern TP have experienced significant northward crustal convergence since the Late Eocene, relative to the reference poles of the Tarim and Qaidam Basins. These contrasting patterns of crustal movement suggest that the convergence between India and Asia has not led to substantial lateral crustal escape from the southeastern TP since the Oligocene, and that the ongoing northward migration of the EHS represents the primary driving force that quasi‐synchronously caused the southeastern margin of the TP to undergo significant clockwise crustal rotational deformation while maintaining a stable latitudinal position since approximately 28.0–24.0 Ma.