新疆罗布泊45kaBP以来沉积物元素地球化学特征及其环境指示意义

根据罗布泊新湖湖心区KY01孔沉积物中常量和微量元素的含量,应用主成分分析方法,提取了控制沉积物化学组成的3个主因子。其中第1主因子对沉积物化学组成具有绝对控制作用,通过详细分析认为该因子可作为塔里木河流域气候干湿变化的代用指标。结合剖面5个AMS14C测年结果所建立的时间标尺,初步重建了塔里木河流域4.5万年以来气候干湿变化历史。结果显示,近4.5万年来塔里木河流域气候呈逐步干旱化趋势,其中末次间冰阶中晚期以湿润气候为主,末次冰期晚冰阶以来变为以干旱气候为主,但末次冰消期晚期-全新世早期发生过明显的气候转湿事件,极端干旱气候出现在中晚全新世以来。罗布泊新湖湖心区KY01孔地化指标还揭示出塔里木河流域的水热组合模式可能是多样的,并非简单地遵循单一的西风型"冷湿-暖干"水热组合模式。

ELEMENT GEOCHEMISTRY OF LACUSTRINE SEDIMENTS IN LOP NUR AND THEIR ENVIRONMENTAL SIGNIFICANCE OVER THE PAST 45KA BP

Major and minor geochemical elements in the sediments of core KY01 from the center of the New Lake district of the Lop Nur, were measured for paleoclimatic reconstruction. Three principal factors were identified based on principal component analysis of these elements. The first principal factor, which absolutely controls the geochemical composition of the sediments, can be used to represent the changes in humidity of the Tarim River Basin. On the basis of the dating result of AMS14C, the evolution history of regional climate during the past 45ka is evaluated. The climate of the Tarim River Basin shows a gradually drying tendency. It was humid during the mid-late last interglacial epoch and turned into drought since the late stadial of the last glaciations, with the exception of one distinct humidity event during the late last deglaciation-Early Holocene. It is also revealed that the climate change pattern of the Tarim River Basin is various rather than one simple westerly-dominated climate pattern.