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对岷江上游地区叠溪古堰塞湖底部沉积物进行AMS14C定年,得到其沉积时间起始时间约为40.5kaBP。通过沉积物粒度特征的研究得知,粒度指标可以反映降水量变化进而反映气候干湿变化,此外,粒度均值曲线与格陵兰冰心(GISP2)及南京葫芦洞石笋氧同位素曲线的显著相似性说明,粒度特征对全球性气候变化有响应,可以反映气候的冷暖变化。由此,研究区古气候演变可以划分为3个阶段:阶段Ⅰ(40.5～33.4kaBP)气候冷干,阶段Ⅱ(33.4～31.7kaBP)气候暖湿,阶段Ⅲ(31.7～31.1kaBP)气候较暖湿。而粒度均值曲线与冰心及石笋氧同位素曲线的差异,一方面可能是由于地理位置的差异,另一方面可能与当时太阳辐射变化情况以及季风作用有关。
AMS14C dating of the sediments at the bottom of the Damian ancient dammed lake in the upper reaches of the Minjiang River resulted in a deposition time of about 40.5kaBP. Through the study of grain size characteristics of sediment, it can be seen that the grain size index can reflect the change of precipitation and then reflect the change of climate. In addition, the significant similarity between the grain size mean curve and oxygen isotope curve of Greenpeace (GISP2) and stalagmite of Hulu Cave in Nanjing shows that the grain size Features respond to global climate change and can reflect changes in climate. Therefore, the evolution of paleoclimate in the study area can be divided into three stages: the stage I (40.5-33.4kaBP) is cold and dry, the stage II (33.4-31.7kaBP) is warm and wet, and the stage III (31.7-31.1kaBP) is warmer wet. The difference between the mean grain size curve and the oxygen isotopic curve of Bingxin and stalagmite may be due to the difference in geographical location on the one hand and the solar radiation changes and the monsoon at that time on the other hand.