黄土高原350～280ka PB气候迁移研究

A subtropical climate study in the Loess Plateau during 350-280ka BP

根据野外调查和室内鉴定、分析了黄土高原350～280 ka PB前后的气候迁移变化问题。资料表明,在地处黄土高原南缘的陕西长安少陵塬第3层古土壤形成中晚期和第4层古土壤形成的早期有代表荒漠草原环境的石膏发育,指示当时黄土高原气候发生了显著的干旱化与大幅度的荒漠草原南迁,与现在这个地区气候相比,气候带向南迁移了约4个纬度,也说明在这段时间内荒漠草原广布于黄土高原。石膏的发育还揭示,在350～280 ka PB前后黄土高原气候发生了性质的转变,第3层古土壤发育中晚期和第4层古土壤发育早期最少各有一个时期气候特别冷干,当时该区已基本不受夏季风的影响,并处于冬季风气候控制的环境下。

On the basis of field research and laboratory identification and analysis,this thesis studies the changes of climate in Loess Plateau during about 350-280 ka BP.The data shows the formation of gypsum,which represents the desert-steppe environment,during the middle and late stages of the third stratum and the early stages of the fourth stratum of the palaeosol formation in Shaoling tableland of Chang＇an on the southern edge of Loess Plateau.It indicates the remarkable drying of climate and the southward movement of the desert-steppe during that time.Compared with the climate in this region today,the climate zone has moved southward by four degrees latitude,showing the widespread of desert-steppe in Loess Plateau in this time.The formation of gypsum also shows that during about 350-280 ka BP there was at least one stage of cold and dry climate respectively in the middle and late stages of the third stratum and the early stages of the fourth stratum of the palaeosol formation.This region was almost not under the influence of the summer monsoon,but under the influence of the winter monsoon during that time.