2.5 Ma以来中国陆地孢粉记录反映的古气候变化

Climate changes on Chinese continent since 2.5 Ma: Evidence from fossil pollen records

  • 摘要: 第四纪作为地质历史中距今最近的一个时期,其气候演化过程备受关注。然而,受研究材料的限制,该时段内气候演化历史研究有限且存在一定的不一致性。为此,本文选取中国陆地第四纪时期(2.5 Ma以来)的48篇孢粉记录资料作为研究对象,对孢粉组成结果进行再分析,探讨孢粉中记录的第四纪气候演化信息。结果表明,研究区域2.5~1.5 Ma期间气候波动变冷且明显偏干,1.5~1.0 Ma期间东部地区气候偏湿而西北地区和青藏高原地区则偏干,1.0 Ma以来整体气候波动频繁。同时,孢粉记录中保存的气候演化历史与第四纪亚洲季风演化具有较好的一致性,约2.5 Ma亚洲冬季风逐渐增强,该阶段气候较为干旱;在1.5 Ma东亚夏季风呈现增强的趋势,带来较多降水,气候湿润;而1.0 Ma以来冬季风增强夏季风减弱,气候又逐渐变干。

     

    Abstract: Climate change during Quaternary has been a hot spot in geosciences for decades. However, discrepancies remain among scholars up to date. In this paper, 48 fossil pollen records from Chinese continent, which cover the whole period of Quaternary, were selected and synthesized for regional climate variations in order to better understand the historical evolution of Quaternary climate. Pollen data were interpolated and mapped using the method of Inverse Distance Weighting (IDW) for spatial distribution patterns. According to the fossil pollen records, Quaternary climate variation on Chinese continent could be summarized as follows. During the period of 2.5~1.5 Ma, the region was dominated by fluctuated cold and dry climate. During the period from 1.5 to 1.0 Ma, it was warm and wet in the eastern part but dry in the northwestern part and the Tibetan Plateau. More fluctuations appeared since 1.0 Ma. The climate variation revealed by pollen records shows a good consistance with the Quaternary monsoon evolution: Asian winter monsoon gradually strengthened after 2.5 Ma while the climate was relatively dry. The East Asian summer monsoon, however, intensified around 1.5 Ma, which probably brought in more precipitation and led to the overall wet climate. The region returned to a drying trend again since 1.0 Ma with the retreat of summer monsoon.

     

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