Magnetostratigraphy of the Niubao Formation in the Bangong‐Nujiang Suture Zone: Constraints on the Amount of Crustal Shortening of the Tibetan Plateau Since 60 Ma

Abstract

The Early Cenozoic sedimentary archives of Tibet are crucial for elucidating the geodynamic processes related to continental collision, particularly crustal deformation and shortening. However, the lack of a reliable chronostratigraphic framework for the Cenozoic sedimentary basins in central Tibet has hindered a comprehensive understanding of the influence of the continuous India‐Asia convergence process on the tectonic evolution of the Tibetan hinterland. Here, we report new magnetostratigraphic ages and paleomagnetic results for the Niubao Formation exposed in the northern bank of the Siling Co. Positive field tests and microscopic observations suggest that the remanence is primary. We determine that the depositional age of the measured section was between 59.2 and 48.6 Ma. Our results reveal that the paleogeographic location of the Bangong‐Nujiang Suture Zone during the Late Paleocene–Early Eocene was 25.4 ± 2.1°N, thus supporting the model of two‐stage collision between India and Asia.