青海湖QH-2000钻孔沉积物粒度组成的古气候古环境意义

The Grainsize of the Core QH-2000 in Qinghai Lake and Its Implication for Paleoclimate and Paleoenvironment

据孢粉记录所划分的气候演化阶段,研究了青海湖QH-2000孔沉积物粒度组成的变化.结果表明,冷干和暖湿气候条件下沉积物的粗颗粒组分明显增多;介于二者之间的气候条件下,沉积物的粒径变化相对较平缓. QH-2000孔沉积物粒度的波动特征表明:晚冰期冰川的消融开始于14300aBP左右;博令(B lling)暖期是冰川大量消融的时期,冰融水对青海湖的补给结束于博令暖期的晚期,即12000 aBP左右;新仙女木冷事件和8200aBP左右的冷事件具有突变性的特点.全新世大暖期结束后,气候在转型过程中具有相对冷暖和干湿的快速波动特征;2100-0 aBP间,沉积物粒度的变化特征同人类活动有关.

The changes of grainsize of the core QH-2000 have been studied in the different stages of palaoclimatic evolution indicated by pollen analysis in Qianghai Lake. The results show that the coarse grain obviously increases in the sediments formed in the conditions of cold-dry and warm-moist climate and the grain variation is relatively little in the sediments formed between these two climate conditions. The fluctuating characteristics of the grainsize in the core QH-2000 indicate that the melting of the glacier began at ca. 14300 aBP during the Late glacial, and the glacier melting was large during the B lling warm period and ended at the late B lling warm period viz. ca. 12000 aBP. The Younger Dryas and the 8200 aBP cold and dry event were abrupt. After the Holocene Megathermal, the climate fluctuated largely and frequently from warm to cold and from moist to dry with the climate type being changed. The composition of the grainsize between 2100 to 0 aBP by any possibility bears some relation to human activities.