西北干旱区石羊河流域末次冰期晚期气候不稳定性记录

Unstability Record of Late Glacial Later Period in the Shiyang River Basin of Arid Northwestern China

通过对我国西北干旱区石羊河流域三角城末次冰期最盛期晚期 -晚冰期地层剖面沉积物中有机质碳同位素分析 ,表明在季风边缘带的沉积地层中较详细地记录了这一时期气候快速颤动 ,发生千年至百年尺度的冷干—温湿变化 ,高分辨的有机质碳同位素组成与GRIP氧同位素组成有较好的可比性 ,表明与全球古气候变化有明显的联系 ,也反映在末次冰期最盛期与晚冰期过渡期气候温湿 ,陆地植被比较发育 ,可能与东亚季风有关。有机质碳同位素这一指标对气候记录较敏感 ,是重建干旱区高分辨古气候演化模式十分有效的手段 ,在季风交汇带能灵敏地记录到气候快速变化。

Carbon isotopic compositions of organic matters in the sediments during late Glacial Maximum and Late Glacial Period have been analyzed in arid semiarid areas of northwestern China. It shows that the sediment have recorded in detail the process of climatic oscillation that changed from dry and cool to warm and wet in thousand or hundred years scale during this period in the transition of monsoon edge belts. High resolution record of organic carbon isotopic compositions is the same as that of GRIP oxygen isotopic composition. It also indicates that there is a relative climatic changes between the globe and arid China. The climate was warm and wet in the transition period of late Glacial Maximum to Late Glacial, and terrestrial plants grew briskly. And the monsoon had taken an important action in the climatic oscillation in Shiyang river basin. The proxy of δ 13 C is the effective indicator of reconstructing the palaeoclimatic variation in the arid China because of its sensitivity to the climatic changes.