【摘要】 在中国新近系建阶研究中,文章作者对中新统最下部的一个阶谢家阶层型剖面开展了古地磁、孢粉等方面的综合研究工作。文中是在磁性地层学的时间标尺上,着重讨论孢粉植物群的变化规律。谢家阶层型剖面中发现的孢粉组合特征,总体上与我国中新世早期的孢粉植物群变化规律相一致。但裸子植物花粉,尤其是云杉(Picea)花粉的含量在两个含孢粉丰富的样品中,由下到上明显增加,反映出研究区早中新世气候具有趋冷特征,与同期深海氧同位素变化规律可相对比。而耐旱植物,尤其是藜科(Chenopodiaceae)和蒺藜科(Zygophyllaceae)白刺属(Nitraria)花粉的含量明显降低,反映谢家期后期孢粉组合所指示的湿度具有较明显的增加,推测与东亚季风在新近纪的发展存在着一定的耦合关系。此外,蒿属(Artemisia)花粉在样品中时有见到,与其在我国新近纪地层中的分布规律相一致,与车头沟剖面古地磁的测量结果相吻合。更多还原

【Abstract】 During the establishment of Neogene stages in China,a comprehensive study on paleomagnetism and palynology in the stratotype section of the Neogene Xiejian Stage has been done.The pollen results on the framework of the paleomagnetic time scale were reported herein.Palynological assemblage from the stratotype section of the Xiejian Stage is largely comparable with the overall characteristics of the Early Miocene palynoflora in China as a whole.However,the amount of gymnospermous pollen grains,especially Picea,shows a signifi-cant increase upward in the two richly fossiliferous samples,inferring a cooling climate,which is more or less comparable with the δ 18 O curve from the Ocean Drilling Program.Conversely,pollen grains from the xerophytes,such as Chenopodiaceae and Nitraria display a significant decrease upward,indicating an increasing humidity in the upper part of the Xiejian Stage,which could be a coupling with the development of the East Asian Monsoon in Neogene.Additionally,common occurrence of Artemisia in the samples,is in accordance with its distribution in the Neogene of China,and is largely in agreement with the paleomagnetic results.更多还原