Crustal Clockwise Rotation of the Southeastern Edge of the Tibetan Plateau Since the Late Oligocene

Abstract

AbstractThe ambiguous temporal relationship between the crustal clockwise rotation and the activity of block boundary strike‐slip faults of the southeastern edge of the Tibetan Plateau has led to an incomplete understanding of the Cenozoic tectonic evolution of Southeast Asia. Based on the Pleistocene paleomagnetic data of the present work and previous Paleogene and Pliocene paleomagnetic data form the south side of the Eastern Himalayan Syntaxis (EHS), we confirmed that the southern edge of the EHS experienced strong clockwise rotation with an average rotational rate of 3.20‐3.02°/Myr since the late Oligocene, indicating that the crustal clockwise rotation of the southeastern edge of the Tibetan Plateau was commenced no earlier than ∼25.7 ± 2.5 Ma. The block boundary strike‐slip faults of the southeastern edge of the Tibetan Plateau began their major activity phase since ∼28 Ma, which was significantly synchronous with the northward indentation of the Indian Plate and the West Burma Block into the Eurasia to form the EHS, but was earlier than the initial clockwise rotation of the southeastern edge of the Tibetan Plateau. These temporal relationships probably indicate that the northward indentation of the Indian Plate and West Burma Block into the Eastern Himalayan orogenic belt to form the EHS since ∼28 Ma should be the paramount inducement to the crustal clockwise rotation and promote the major activity of block boundary strike‐slip faults of the southeastern edge of the Tibetan Plateau.