渭北旱塬黄土记录的晚冰期以来短尺度气候变化

Late-glacial and Holocene climate change recorded in loess profile in Weibei loess tableland

通过对长武下孟村黄土剖面的野外考察和磁化率、粒度、吸湿水含量分析 ,探讨了该地区晚冰期以来气候变化规律 .研究结果表明 ,该剖面较好地记录了新仙女木期 (YD)和博令 阿勒罗德事件 (BL +AL)短尺度较小幅度气候变化事件 .对应全新世气候最适宜期 ( 850 0— 31 0 0a .BP) ,该地为黑垆土成壤期 .从 31 0 0a .BP开始 ,季风气候格局快速转变 ,气候干旱化 ,土壤和土地资源退化 .所以 31 0

Field investigations,grain size analysis ,hygroscopic water and magnetic susceptibility measurement in a loess profile of Late glacial and Holocene in Changwu,Shaanxi,have revealed the characteristics of the climate change during late 14700 years. The results show hat the Younger Dryas and Bolling and Allerod short term climatic events are well recorded in the profile. Between 8500～3100 a.BP,Pedogenic process was very strong. A layer of Heilu soil was formed on the Loess tableland. There is a transformation phase between 3400～3100 a.BP. It represents a climate change from the period dominated by Southeastern monsoon to the period dominated by northwestern monsoon. From 3100a.BP soil degradation is remarkable. A layer of Loess has been accumulated since 3100 a.BP, which has the Heilu soil buried. This means the last 3100 years is a dry period with intensified dust accumulation.