【摘要】 本文选择在第四纪沉积厚度较大的北京昌平地区行打钻取样,获得连续的沉积样品,通过AMS14C测年手段建立年代框架,提取钻孔上部2~12.4 m沉积物的孢粉,通过分析孢粉的质量浓度及种属组合变化,进而恢复北京地区的古气候状况。研究表明北京昌平地区30 000 yr BP以来的古气候演变经历了4个阶段:29 090~27 200 yr BP为气候寒冷湿润;27 200~19 100 yr BP,主要发育以蒿、藜为主的中旱生草原,反映了这一时期寒冷干燥的气候特征;19 100~11 700 yr BP,主要分布以蒿、藜为主的草原植被,但是覆盖度很低,说明气候进一步变冷变干,是北京气候最寒冷干旱的时期;11 700~4 460 yr BP,为全新世早中期,植物种类丰富,适宜木本植物生长,植被发育针阔叶混交林,气候较为温暖湿润。更多还原

【Abstract】 The continuous sediments were collected in Changping district of Beijing,where the quaternary sedimentary is rather thick. A chronostratigraphic framework of the sediments was established by AMS14 C dating,and the concentration and species composition of pollen in the sediments were analyzed. The results showed the climate change in Beijing since 30 000 yr BP was divided into 4 stages: the climate was cold and humid during 29 090 ~27 200 yr BP; in 27 200 ~ 19 100 yr BP,the climate was cold and dry which dominated by ArtermisiaChenopdiaceae steppe; in 19 100 ~ 11 700 yr BP,the Artermisia-Chenopdiaceae steppe’s coverage became lower and the climate continued to be colder and drier; the last stage corresponded to early and middle period Holocene during 11 700 ~ 4 460 yr BP,the climate was warm and humid,there were varieties of plants and mixed coniferous broad leaved forest developed.更多还原