New Paleomagnetic results from Late Triassic limestone of the Eastern Qiangtang Terrane: Implications for the closure of the Paleo-Jinshajiang Ocean

Abstract

To constrain the drift history of the Eastern Qiangtang Terrane and the closure time of the Paleo-Jinshajiang Ocean, we conducted a paleomagnetic study of Late Triassic limestones in the Qamdo region of the Eastern Qiangtang Terrane. The results of the rock magnetic, petrographic, and reversal test indicate the limestones carry primary magnetizations. Our new paleomagnetic data provide a Late Triassic paleopole of 30.9°N, 161.4°E (A₉₅ = 8.4°), which corresponds to a paleolatitude of 35 ± 8.4°N for the study area. Integrating these data with existing paleomagnetic results and geological evidence, we determine that the Eastern Qiangtang Terrane was situated at a relatively constant paleolatitudinal position without significant N-S displacements during ∼230–209 Ma. We conclude that the Paleo-Jinshajiang Ocean in the Qamdo region had already closed before ∼221 Ma, and likely around ∼230 Ma.