Eocene Rotation of the Northeastern Central Tibetan Plateau Indicating Stepwise Compressions and Eastward Extrusions

When and how the TP underwent uplift and deformation are still under heated debate. We present paleomagnetic evidence for the NB in the northeastern central TP to help decipher the potential plateau deformation mechanism. Magnetostratigraphy with zircon U-Pb age of volcanic rock demonstrates that the NB basin deposited during 52.5-35.0 Ma. Paleomagnetic declinations indicate that the basin experienced counterclockwise rotation of 25.9 +/- 7.2 degrees during 52-46 Ma and clockwise rotation of 24.4 +/- 9.7 degrees during 41-35 Ma, which coexisted with the intrusion and explosion of volcanic rocks at 51-46 and 39-35 Ma. We proposed a stepwise compression and extrusion model to interpret the basin deposition, rotation, and volcanism by northward compression and eastward extrusion of the eastern Lhasa and Qiangtang Blocks (Proto-TP) in relation to the Sichuan Basin as early response to the India-Asia collision.