资源环境科技发展态势分析平台

The tectonic evolution of the eastern Paleo‐Tethys in the Three‐Rivers headwater region remains uncertain, especially because of the lack of quality paleomagnetic data from the east Eastern Qiangtang Terrane (EQT). Here, we present an integrated paleomagnetic and zircon U‐Pb geochronologic study of the Gadikao Formation (Fm.) volcanic rocks in the EQT. This previously assumed Carboniferous or Permian rock unit is now zircon U‐Pb dated to ∼254‐248 Ma. Our new high quality (29 sites and 257 samples) inferred primary paleomagnetic results yield a robust Permo‐Triassic boundary paleopole of 59.7°N, 228.2°E (A₉₅=3.3°), with a paleolatitude of 10.0±3.3°N for the study area. Integrated with other reliable Permo‐Triassic paleomagnetic data of the EQT and the Tarim Block and other lines of geologic evidence, we propose that the EQT drifted continuously northward during 300‐200 Ma and the Paleo‐Tethys Ocean probably closed at ∼232‐220 Ma around the Qamdo region, most likely at 230 Ma.