依据孢粉记录初探青海湟水流域二级阶地的成因

青藏高原边缘河流阶地的成因一直是研究的热点。对湟水流域二级阶地形成时的孢粉分析结果表明:该时期湟水流域存在明显的垂直植被带且结构简单,山地高处生长着以云杉为主的森林,谷地则生长以蒿属、藜科为主要类型的草本植被。同时结合该时期相邻地区的孢粉资料并和现代植被特征比较,湟水流域二级阶地的植被显示出冰期的植被特征,阶地冲积物也是在冰期堆积的,河流可能在间冰期下切。气候变化在阶地形成过程中可能有一定的作用。

Origin of the second terraces in the Huangshui drainage area, Qinghai, China, studied based on sporopollen records.

The study of the origin of river terraces at the edges of the Qinghai-Tibet Plateau has long been a hot topic.Analysis of the sporopollen on the second terrace of the Huangshui River drainage area indicates that during the period of formation of the second terraces,a distinct vertical vegetation zone with simple structure occurred in the area,with forest dominated by Picea growing in higher places of mountainous areas and herbaceous plants dominated by Artemisia and Chenopodiaceae growing in valleys.According to these features,combined with the sporopollen data in the neighboring areas during that period and a comparison with the characteristics of modern vegetations,the vegetations in the second terraces of the Huangshui drainage area show the features of the vegetations in the glacial period,the alluvial deposits on the terraces were also piled up in the glacial period and the river probably incised the strata in the interglacial period.The climatic change might play an innegligible role in the formation process of the river terraces.