The uppermost Oligocene Kailas flora from southern Tibetan Plateau and its implications for the uplift history of the southern Lhasa terrane
The uppermost Oligocene Kailas flora from southern Tibetan Plateau and its implications for the uplift history of the southern Lhasa terrane
复制标题
青藏高原南部渐新世凯拉什植物群及其对拉萨地体南部隆升历史的意义
DOI：
10.1016/j.palaeo.2018.04.017
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发表时间：
2019-02-01
影响因子：
3
通讯作者：
Guo, Shuangxing
中科院分区：
文献类型：
--
作者：
Ai, Keke;Shi, Gongle;Guo, Shuangxing
稳定同位素研究一致表明拉萨地体在中新世之前达到了接近现在的高度。本文报道了拉萨地体南部西部克拉斯盆地克拉斯组的一个植物巨化石组合。U-Pb测年和磁地层对比表明，克拉斯组研究剖面的年龄在25.1 ~ 21.8 Ma之间，化石区系发生在23.3 Ma（晚渐新世）。渐新世上部凯拉斯古植物区系多样性较低，以杨科、桦木科和豆科为主。根据化石植物现存类似物的共存范围，它极有可能代表一种落叶阔叶植被，表明卡拉斯盆地在渐新世晚期处于温带湿润环境，古海拔在1500-2900 m之间。这与晚渐新世存在的横跨整个拉萨地体南部的连续的高冈底斯山脉相冲突。现有证据表明，拉萨地体南部在晚渐新世之后发生了强烈的隆升。
The Lhasa terrane is thought to be a key region for understanding the elevation history of the southern Tibetan Plateau after collision of continental India and Asia in early Paleocene. Stable isotopic studies consistently suggest that the Lhasa terrane had reached its near-present elevation before the Miocene. In this paper we report a plant megafossil assemblage from the Kailas Formation of the Kailas Basin in western part of the southern Lhasa terrane. Our U-Pb dating and magnetostratigraphic correlation show that the studied section of the Kailas Formation ranges from 25.1 Ma to 21.8 Ma in age, and that the fossil flora occurred at 23.3 Ma (latest Oligocene). The uppermost Oligocene Kailas fossil flora is low in diversity and dominated by Populus, Betulaceae and legume. It most likely represents a deciduous, broad-leaf vegetation and suggests a temperate, humid environment with a low to moderate palaeoelevation of 1500-2900 m in the Kailas Basin during the latest Oligocene, based on the co-existing range of the living analogues of the fossil plants. This conflicts with the existence of a continuous, high Gangdese Mountains stretching across the whole southern Lhasa terrane in the late Oligocene. Available evidence appears to suggest strong uplift of the southern Lhasa terrane after the latest Oligocene.