资源环境科技发展态势分析平台

Paleomagnetic studies on the syncollisional magmatic eruptions provide a direct way to understand when and where the Paleo-Tethys closed. We report a well-dated paleomagnetic pole from the southern Lancangjiang volcanic belt in western Yunnan of China. Stable Characteristic Remanent Magnetizations (ChRMs) were isolated from 21 sites at high temperatures following step-wise thermal demagnetization. The data pass fold, reversal, and conglomerate tests and are interpreted to be primary thermal remanent magnetizations. The new paleomagnetic pole (46.1 degrees N/176.2 degrees E, K=44.9, A(95)=4.8 degrees, N=21) yields a paleolatitude of 26.0 +/- 4.8 degrees N at the reference site (23.0 degrees N/100.4 degrees E) in the southern Lancangjiang area. This direct paleo-latitudinal constraint on the Paleo-Tethys suture zone in western Yunnan indicates that the north branch of the Paleo-Tethys Ocean closed no later than the Carnian Age of Late Triassic, and confirms a geographic linkage between the North Qiangtang and Indochina Blocks at least during the Early Permian to Late Triassic.