云南大理点苍山地区更新世晚期沉积地层的ESR测年研究

STUDY ON ESR DATING OF DEPOSITIONAL STRATUMS OF LATE PLEISTOCENE EPOCH IN DIANCANGSHAN AREA ABOUT DALI CITY IN YUNNAN PROVINCE

本文采用电于自旋共振（ESR）方法测定了云南点苍山地区更新世晚期沉积地层的形成年代。测年结果显示；（1）点苍山地区冰川沉积物的ESR年龄均小于140．35KaBP，说明该地区的第四纪冰川作用最早出现于中更新世晚期，主要发生于晚更新世；（2）点苍山西麓平坡附近最高一级基座阶地的堆积时代为184．3KaBP，证明西洱河阶地系列为中更新世以来的产物；（3）点苍山东侧白雀寺地区深3．7m处的褐红色地展形成的ESR年龄为12218KaBP，揭示出该地层形成于深海氧同位素5e阶段所代表的一个温热气候时期。

In this paper, ages of depositional stratums of the late pleistocene epoch in Diancangshan area about Dan city in Yunnan province are determined with ESR dating method. The outcome of dating demonstrates: (1) the ESR dating of glacial deposites in Diancangshan area is no more than 140. 35 ha B. P., which shows that the earliest quaternary glaciation was ocurred in the later part of the middle pleistocene epoch and the quaternary glaciations were mainly occured in the later pleistocene epoch; (2) Deposited ages of the highest river terrace near the Pingpo town in the western foot of the Diancangshan Mountains are about 184. 3ha B. P., which displays that the terraces of the Xi-er river have deposited since the middle pleistocene epoch ; (3) The drab -red stratum lay at 3. 7m below ground level about the Baiquesi area in the eastern foot of the Diancangshan Mountains is deposited about 122. 18ha B. P. (ESR dating) which reveals it takes form in a damp-hot stage representing deep sea oxygan isotopes (5e).