First Paleomagnetic Results From Late Triassic Volcanic Rocks of the Yidun Terrane, Eastern Tibetan Plateau: Constraints on the Closure of the Paleo‐Tethys Ocean

Abstract To constrain the temporal and spatial evolution of the Ganzi‐Litang Paleo‐Tethys Ocean, this study presents the first paleomagnetic results from Late Triassic volcanic rocks in the Yidun terrane in the eastern Tibetan Plateau. The mean paleomagnetic direction for 27 sites is Ds = 39.2°, Is = −52.9°, κs = 42.2, α 95 = 4.3°, and the paleomagnetic pole is located at 14.9°N, 247.1°E ( κ = 31.1 and A 95 = 5.1°). Fold, reversal, and paleosecular variation tests, together with petrographic investigations, confirm the primary origin of the characteristic remanent magnetization. These results indicate that the Yidun terrane was situated at ∼34.8°N at ∼231 Ma. Combined with available paleomagnetic and geological evidence, this suggests that: (a) the Ganzi‐Litang Ocean closed no later than ∼231 Ma; (b) the Paleo‐Tethys Ocean finally closed during the early Late Triassic; and (c) the final closure of the Paleo‐Tethys Ocean was nearly synchronous from east to west.