兰州黄土高分辨率定年模型的探讨

On the high-resolution age model for the Lanzhou loess

运用末次间冰期以来兰州西津黄土钻孔和靖远剖面的磁化率、粒度,分别以综合年龄模型MG、粒度年龄模型、磁化率年龄模型、综合年龄模型GM为计算方法,建立了兰州和靖远黄土末次间冰期以来的4种时间标尺.经过线性拟合、多项式拟合的相关性分析和具有同步信号的气候变化事件的验证,表明综合年龄模型MG具有较高精度,在一定程度上证明了该方法建立兰州黄土地层年代标尺的可行性.在重建第四纪兰州黄土长序列高分辨率、高精度的年龄框架时,磁化率年龄模型用于计算古土壤层,粒度年龄模型用于计算黄土层,得出综合年龄模型MG比单个年龄模型计算整个剖面年龄更加准确,相对精度更高.

The last interglacial age sequence of both Lanzhou and Jingyuan sections were reconstructed using their magnetic susceptibility and grain size. Using the integrated age model MG, magnetic susceptibility model, grain size model and integrated age model GM, respectively built four time scales of both Lanzhou and Jingytlan section since the last interglacial age. Based on a detailed linear and polynomial fitting correlation analysis and a synchronous signal checking of particular climate events, it was proposed that the integrated age model MG is of high accuracy and suitable for the chronosequence of in the western Chinese Loess Plateau, especially for the thick Lanzhou loess. In detail, the magnetic susceptibility age model was used to calculate the age of the paleosol layer while the grain size age model was suitable for calculating the loess layer. It is proved that the integrated age MG is more accurate than the single model to calculate the total profile age and is suitable for reconstructing a high-resolution Quaternary age model for the loess in Lanzhou.