Fang Xiaomin, Dupont-Nivet Guillaume, Wang Chengshan, Song Chunhui, Meng Qingquan, Zhang Weilin, Nie Junsheng, Zhang Tao, Mao Ziqiang, Chen Yu
Center for Excellence in Tibetan Plateau Earth Sciences, Chinese Academy of Sciences (CAS), Beijing 100101, China.
Key Laboratory of Continental Collision and Plateau Uplift, Institute of Tibetan Plateau Research, Chinese Academy of Sciences (CAS), Beijing 100101, China.
Sci Adv. 2020 Dec 9;6(50). doi: 10.1126/sciadv.aba7298. Print 2020 Dec.
Knowledge of the topographic evolution of the Tibetan Plateau is essential for understanding its construction and its influences on climate, environment, and biodiversity. Previous elevations estimated from stable isotope records from the Lunpola Basin in central Tibet, which indicate a high plateau since at least 35 Ma, are challenged by recent discoveries of low-elevation tropical fossils apparently deposited at 25.5 Ma. Here, we use magnetostratigraphic and radiochronologic dating to revise the chronology of elevation estimates from the Lunpola Basin. The updated ages reconcile previous results and indicate that the elevations of central Tibet were generally low (<2.3 km) at 39.5 Ma and high (3.5 to 4.5 km) at ~26 Ma. This supports the existence in the Eocene of low-elevation longitudinally oriented narrow regions until their uplift in the early Miocene, with potential implications for the growth mechanisms of the Tibetan Plateau, Asian atmospheric circulation, surface processes, and biotic evolution.
了解青藏高原的地形演化对于理解其形成过程以及它对气候、环境和生物多样性的影响至关重要。先前根据西藏中部伦坡拉盆地稳定同位素记录估算的海拔高度表明，至少自3500万年前以来该高原就已存在，但最近发现的明显形成于2550万年前的低海拔热带化石对这一观点提出了挑战。在此，我们利用磁地层学和放射性年代测定法来修正伦坡拉盆地海拔高度估算的年代序列。更新后的年代与先前结果相吻合，表明西藏中部在3950万年前海拔普遍较低（<2.3千米），在约2600万年前海拔较高（3.5至4.5千米）。这支持了始新世存在低海拔纵向狭窄区域直至中新世早期隆升的观点，这对青藏高原的生长机制、亚洲大气环流、地表过程和生物演化可能具有重要意义。
