Qaidam Basin leaf fossils show northeastern Tibet was high, wet and cool in the early Oligocene
Qaidam Basin leaf fossils show northeastern Tibet was high, wet and cool in the early Oligocene
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藏北柴达木盆地新生代地层物源新认识：近古河流沉积物碎屑锆石U-Pb联合测年的制约
DOI：
10.1016/j.palaeo.2019.109254
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发表时间：
2020
影响因子：
5.3
通讯作者：
Gongle Shi
中科院分区：
文献类型：
--
作者：
Bowen Song;Robert A. Spicer;Kexin Zhang;Junliang Ji;Alex;er Farnsworth;Alice C. Hughes;Yibo Yang;Fang Han;Yadong Xu;Teresa Spicer;Tianyi Shen;Daniel J. Lunt;Gongle Shi
今天的半干旱和干旱的中亚地区的古近纪环境的量化和知识的北方西藏的古海拔仍然难以捉摸，但这两个是至关重要的了解青藏高原的增长和亚洲季风发展之间的相互关系。本文应用气候-叶分析多元程序（CLAMP）和湿焓方法，对柴达木盆地新发现的早渐新世（30.8Ma）叶化石进行了定量重建。研究发现，早渐新世柴达木盆地底部植被高度约为1.33 ± 1.4km，与现今盆地底部植被高度相似，但高于当时喜马拉雅山脉的上升高度，经历了温和湿润的气候。冬季接近冰点（1.4 ±3.5 ℃），夏季凉爽（1.23 ±2.9 ℃）。年降水量可能超过1000毫米（生长季降水量为1229 ±643毫米），季节性较弱（非季风），夏季比冬季干燥。这一发现挑战了地球动力学模型，该模型设想了北方西藏的中新世或更晚的隆升以及南部的渐进隆升。
The Paleogene environment of today’s semi-arid and arid Central Asia is poorly quantified and knowledge of the paleoelevation of northern Tibet remains elusive, yet both are crucially important for understanding inter-relationships between growth of the Tibetan Plateau and Asian monsoon development. Here, we apply the Climate-Leaf Analysis Multivariate Program (CLAMP) and moist enthalpy method to the newly discovered early Oligocene (30.8 Ma) fossil leaves from the Qaidam Basin, to reconstruct quantitatively the paleoclimate and paleoelevation of this critical part of northern Tibet. We find the Qaidam Basin floor vegetation was likely at ∼3.3 ±1.4 km in the early Oligocene, similar to that of the present basin floor but higher than the rising Himalaya at that time, and experienced a temperate, moderately wet climate. Near-freezing (1.4 ±3.5◦C) winters accompanied cool summers (∼23 ±2.9◦C). Annual precipitation likely exceeded 1000 mm (growing season precipitation of 1229 ±643 mm) with subdued (non-monsoonal) seasonality in which summers were drier than winters. This finding challenges geodynamic models that envisage a Miocene or later uplift of northern Tibet and progressive uplift from the south.