Mid-Miocene rapid rise of the Gangdese Mountains, South Tibet, quantified by pollen records

Yang, Yi

EARTH AND PLANETARY SCIENCE LETTERS

2026

692

Li, SF

Resolving the elevation history of the Gangdese Mountains (GMs) is key to understanding the evolution of the entire Tibetan Plateau (TP). Multiproxy paleoelevation reconstructions indicate that the Namling (Wuyu/Oiyug) Basin, eastern GMs, experienced uplift from the late Oligocene to Middle Miocene, accelerating at similar to 15 Ma as inferred from a significant sediment provenance shift at that time. However, whether the rapid rise actually occurred still lacks direct evidence, and the magnitude of this uplift in quantitative terms remains unknown. In this study, pollen analysis of a well-dated section in the Namling Baisn, reveals a distinct vegetation shift from a temperate-subalpine forest to an alpine shrubland/shrub-meadow within the basin at similar to 15 Ma. By integrating pollen and megafossil records, and utilizing high-resolution climate-vegetation modeling, we demonstrate that this vegetation change most likely resulted from a rapid uplift of the Namling Basin at similar to 15 Ma rather than global and/or regional climate changes. We calculate the uplift to be between 525 and 1050 m, exceeding the present-day elevation (similar to 4.5 km) by similar to 1.5-2 km and reaching > 6 km. Based on our modeling results and contemporaneous pollen records from the Central TP, it seems the uplift at similar to 15 Ma was localized and cannot be extended to the entire GM chain. Subsequent subsidence may have been due to ongoing subduction of the Indian plate causing downward drag on the overlying southern Lhasa terrane combined with late Cenozoic east-west extensional collapse of the southern TP.