Botsyun Svetlana, Sepulchre Pierre, Donnadieu Yannick, Risi Camille, Licht Alexis, Caves Rugenstein Jeremy K
Laboratoire des Sciences du Climat et de l'Environnement (LSCE)/Institute Pierre Simon Laplace (IPSL), Commissariat á l'Énergie Atomique et aux Énergies Alternatives (CEA)-CNRS-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Université Paris-Saclay, Gif-sur-Yvette, France.
Department of Geosciences, University of Tübingen, Tübingen, Germany.
Science. 2019 Mar 1;363(6430). doi: 10.1126/science.aaq1436.
Paleotopographic reconstructions of the Tibetan Plateau based on stable isotope paleoaltimetry methods conclude that most of the Plateau's current elevation was already reached by the Eocene, ~40 million years ago. However, changes in atmospheric and hydrological dynamics affect oxygen stable isotopes in precipitation and may thus bias such reconstructions. We used an isotope-equipped general circulation model to assess the influence of changing Eocene paleogeography and climate on paleoelevation estimates. Our simulations indicate that stable isotope paleoaltimetry methods are not applicable in Eocene Asia because of a combination of increased convective precipitation, mixture of air masses, and widespread aridity. Rather, a model-data comparison suggests that the Tibetan Plateau only reached low to moderate (less than 3000 meters) elevations during the Eocene, reconciling oxygen isotope data with other proxies.
基于稳定同位素古高度测定法对青藏高原进行的古地形重建得出结论，约4000万年前的始新世时，青藏高原目前的大部分海拔就已达到。然而，大气和水文动力学的变化会影响降水中的氧稳定同位素，从而可能使此类重建产生偏差。我们使用了一个配备同位素的大气环流模型来评估始新世古地理和气候的变化对古海拔估计的影响。我们的模拟表明，由于对流降水增加、气团混合以及普遍干旱等因素共同作用，稳定同位素古高度测定法不适用于始新世的亚洲地区。相反，模型与数据的比较表明，始新世时青藏高原仅达到低至中度（低于3000米）海拔，从而使氧同位素数据与其他代理指标相协调。
