The Lhasa Terrane Was Still Underway to Its Northward Motion of Being Part of Eurasia at 38 Ma: Key Evidence From the Lunpola Basin of Central Tibet

ABSTRACT The paleogeography and kinematic evolution of the Lhasa terrane during the Cenozoic time are key aspects to understanding the tectonic evolution of the Tibetan Plateau. Previous studies have focused on the paleolatitude reconstruction of the Lhasa terrane before and during the onset of the initial India–Asia collision. However, there exists an important gap between the period immediately after the onset of the India–Asia collision and the precise time at which the Lhasa terrane reached its present‐day latitude in terms of its kinematic evolution throughout the Cenozoic time. To this end, we performed an integrated study including paleomagnetism and isotopic geochronology on the Paleogene sediments of the Niubao (NB) Formation to provide a new constraint on the late Eocene paleolatitude of the Lhasa terrane. In combination with rock magnetic and petrographic results, our obtained results show that 91 inclination‐shallowing corrected characteristic remanent magnetizations (ChRM) are of pre‐folding origin and have passed the reversal test, indicating their primary nature. Based on these inclination‐shallowing corrected 91 filtered ChRM directions from sediments, the paleopole was calculated as λ p = 77.2° N, φ p = 308.2° E, with dp/dm = 3.0°/5.1°. This new result indicates that the Lhasa terrane was at 21.7° ± 3.0° N for the reference site at ca. 38 Ma, suggesting that the Lhasa terrane was still underway to its northward motion before its final arrival at present‐day latitude. This further suggests that a total magnitude of ca. 1700 km crustal shortening was partitioned within Asia since 38 Ma to the present day.