Direct Paleomagnetic Constraint on the Closure of Paleo‐Tethys and Its Implications for Linking the Tibetan and Southeast Asian Blocks

Abstract

Abstract 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°N/176.2°E, K =44.9, A 95 =4.8°, N =21) yields a paleolatitude of 26.0 ± 4.8°N at the reference site (23.0°N/100.4°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.