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冰川冻土 ›› 2021, Vol. 43 ›› Issue (3): 776-785.doi: 10.7522/j.issn.1000-0240.2021.0019

• • 上一篇    下一篇

青藏高原东北缘小水子地区晚中新世-上新世生态演化及其意义

李小苗1,2(),吴泽坤1,2,彭廷江2,马振华1,2,冯展涛2,李孟2,郭本泓2,宋春晖3   

  1. 1.曲阜师范大学 地理与旅游学院,山东 日照 276826
    2.兰州大学 资源环境学院 西部环境教育部重点实验室,甘肃 兰州 730000
    3.兰州大学 地质科学与矿产资源学院,甘肃 兰州 730000
  • 收稿日期:2021-05-19 修回日期:2021-06-09 出版日期:2021-06-30 发布日期:2021-05-18
  • 作者简介:李小苗,讲师,主要从事有机地球化学和环境变化研究. E-mail: lixm0910@foxmail.com
  • 基金资助:
    国家自然科学基金项目(41330745)

Late Miocene-Pliocene ecological evolution on the northeastern Tibetan Plateau and its possible mechanism

Xiaomiao LI1,2(),Zekun WU1,2,Tingjiang PENG2,Zhenhua MA1,2,Zhantao FENG2,Meng LI2,Benhong GUO2,Chunhui SONG3   

  1. 1.College of Geography and Tourism,Qufu Normal University,Rizhao 276826,Shandong,China
    2.Key Laboratory of Western China’s Environmental Systems,Ministry of Education,College of Earth and Environmental Sciences,Lanzhou University,Lanzhou 730000,China
    3.School of Earth Sciences,Lanzhou University,Lanzhou 730000,China
  • Received:2021-05-19 Revised:2021-06-09 Online:2021-06-30 Published:2021-05-18

摘要:

晚中新世-上新世古生态演化是探讨构造-气候-生态环境相互耦合作用的热点议题,该时段不同区域C4植物是否发生大规模扩张及其在时空维度上如何演化等问题尚存争议。以青藏高原东北缘小水子红黏土为研究对象,基于总有机碳同位素重建了小水子地区晚中新世-上新世(6.7~3.6 Ma)的植物生态型,并结合周边结果对C3/C4植被时空演化进行综合对比研究。研究表明:小水子地区晚中新世-上新世以C3植被为主(平均丰度95%),伴生小部分C4植被;C4植被在空间上以六盘山为界呈现东多西少模式,南北方向上在37°~38° N范围内达到峰值;从时间演化序列上来看,4 Ma前小水子地区生态演化与黄土高原大致相同,晚中新世C4植被含量较高、C3植被含量较低,上新世早期C4植被减少、C3植被增多,大气CO2浓度与区域降水变化可能是植被演化的主要影响因素;4 Ma左右夷平面区域构造活动可能导致了小水子地区C4植被差异性演化。

关键词: 青藏高原东北缘, 晚中新世-上新世, 有机碳同位素, 生态演化

Abstract:

The late Miocene-Pliocene ecological evolution has been a hot topic in discussing the interaction of tectonic, climate and ecological environment. However, whether the C4 plants in middle and low latitudes expanded on a large scale and how the ecology evolved on the time-space dimension are still debated. In this paper, based on the organic carbon isotope, the plant ecotype during the interval of 6.7~3.6 Ma covered on Xiaoshuizi area in the northeastern Tibetan Plateau were reconstructed and combined with the surrounding regions, the ecotype and its evolution were discussed. Our results show that the Xiaoshuizi area is dominated by C3 vegetation during the late Miocene-Pliocene (with an average abundance of 95%), accompanied by a small part of C4 vegetation. In space, the abundance of C4 vegetation in the eastern Liupan mountain is higher than that in the western, and in the north-south direction the C4 plant abundance reached the at about 37°~38° N. In terms of time series, ecological evolution of Xiaoshuizi planation surface is roughly consistent with that of the Chinese Loess Plateau before 4 Ma. It shows during the late Miocene C4 vegetation content is relatively high and C3 vegetation content is low, while C4 vegetation reduced and C3 vegetation increased in early Pliocene. The variations of atmospheric CO2 concentration and regional aridification may be the main influence factor for the vegetation evolution. The tectonic activities in the planation surface area may lead to the differential evolution of C4 vegetation in the Xiaoshuizi area.

Key words: northeast edge of Qinghai-Tibet Plateau, late Miocene-Pliocene, organic carbon isotope, ecological evolution

中图分类号: 

  • P512.2