青海湖南岸全新世黄土剖面、气候信息及湖面升降探讨

THE LOESS PROFILE AT SOUTH BANK,CLIMATIC INFORMATION AND LAKE-LEVEL FLUCTUATIONS OF QINGHAI LAKE DURING THE HOLOCENE

本文根据青海湖南岸哈拉力黄土-古土壤剖面气候信息,讨论了青海湖区距今10300年以来气候的四次冷暖和千湿交替变化。其中距今7000—3500年为湖区全新世气候最宜时期,当时年均气温比今高2.5℃,而距今8500—7000年和3500—2800年间年均气温分别比今低5°—6℃和2.5℃。全新世以来青海湖存在四次商湖面时期,它们与气候的四次温湿期一致,最高湖面不超过觋今湖面30m。

According to climatic information,^(14)C dating,spore-pollen analy- sis and grain size data of Halali loess profile,and the distribution and ^(14)C dating of depositional terrace at south bank of Qinghai Lake,the paper discusses the climatic changes in Qinghai Lake area and the Lake level fluctuations since 10300 years B.P.It is pointed out that there are four relatively warm and humid periods in Qinghal Lake area since the Holocene.They are the periods from 10300 years B.P. to 8500 years B.P.,from 7000 years B.P.to 3500 years B.P.,from 2800 years B.P.to 2000 years B.P.,and from 3500 years B.P.to present time.The optimum climate period in Qinghai Lake area was the period from 7000 years B.P.to 3500 years B.P.when polypodium plants grew luxuriantly around Qinghai Lake,it was quite warm and humid,the average annual temperature was 2.5℃ higher than that at present.The cold and dry periods happerned in 8500 years B.P.to 7000 yearsB.P.,3500 years B.P.to 2800 years B.P.and 2000 years B.P.to about 1300 years B.P..Qinghai Lake level generally tended to lower in the Holocene,but there were four periods of relatively stable high lake-level corresponding to warm and humid periods,