Paleomagnetic Results from the Three Rivers Region, SW China: Implications for the Collisional and Accretionary History

Abstract

A comparative analysis of paleolatitudes and latitudinal displacements was undertaken for the South China, Simao, Baoshan, Shan-Thai, Indochina, Qiangtang, Lhasa and Himalayan blocks by using available paleomagnetic data to determine the collisional and amalgamation history of the main blocks in Tibet and the Three Rivers region, western Yunnan, and corresponding age of the Tethys oceans. The results show that ① the Paleo-Tethys separating the Baoshan and South China blocks was likely opened in the Early Silurian; ② the Baoshan block collided with the South China block (SCB) in the Late Permian (～263 Ma) and continued to drift northwards rapidly together with the South China and Shan-Thai blocks until the Late Triassic; ③ the Paleoo-Tethys ranged in age from Early Silurian time to Late Permian time; ④ the Meso-Tethys ranged in age from Early Permian time to Early Cretaceous time, and reached its greatest width of about 42° in latitude in the Late Triassic ; ⑤The Neo-Tethys, separating the Lhasa and Himalayan blocks, opened in the Late Triassic.