2026-08-20 中国科学院（CAS）
＜関連情報＞
- https://english.cas.cn/newsroom/research-news/202608/t20260820_1188654.shtml
- https://www.sciencedirect.com/science/article/abs/pii/S0012821X26004619
花粉記録によって定量化された、中期中新世における南チベットのガンデセ山脈の急速な隆起 Mid-Miocene rapid rise of the Gangdese Mountains, South Tibet, quantified by pollen records
Yi Yang, Robert A. Spicer, Alexander J. Farnsworth, Zhekun Zhou, Jia Liu, Kenji Izumi, Shufeng Li, Tao Su
Earth and Planetary Science Letters Available online: 8 August 2026
DOI:https://doi.org/10.1016/j.epsl.2026.120280
Highlights
- Fossil pollen analysis of the Namling Basin of eastern Gangdese Mtns, south Tibet.
- Montane forests shifted to alpine shrubland in the Namling Basin at ca. 15 Ma.
- Namling Basin was uplifted by 525–1050 m at ca. 15 Ma, ∼1.5–2 km higher than today.
- Climate modeling and pollen records indicate the uplift was localized.
- Indian plate subduction and E-W extensional collapse caused post-15 Ma subsidence.
Abstract
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 ∼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 ∼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 ∼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 (∼4.5 km) by ∼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 ∼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.
