毛乌素沙地南缘全新世自然环境

THE CHANGES OF THE PHYSICAL ENVIRONMENT OF THE SOUTHERN MAOWUSHU SANDY LAND DURING HOLOCENE

根据毛乌素沙地南縁柳树湾剖面的孢粉分析,结合岩性、^(14)C测定等资料,揭示该地全新世植物群落的演替,讨论自然环境的变迁。

The research profile is situated at Liushuwan of southern Maowushu sandy land at about 25 km morth of the Jingbian City of Shannxi Province , 37°46'N, 108°50'E.The profile with a thickness of 6.24 m is fluvial and lacustrine deposits with many layers of sandy-peats. The age of the sediments belongs to Holocene period according to 14C dating.Since 13000 years B. P., herbaceous Artemisia has been dominated in vegetation, and the climate has een always drier in the temperate zcne, during which period the vegetation and the climate changed as follows. In 13000-9000 years B.P.,the climate was dry and cold.In 9000-4000 years B.P., the climate was warm and relatively humid.Since 4000 years B.P., the climate was dry and lukewarm, and it was wet at about 1500 years B.P..The accumulation of sand in the locality existed before 13000 years B.P. and continued until present. In 4000 yeras B.P., the dryness of climate began obvious. During the recent 1000 years, the tendency of the dry climate and the accumulation of sand have been accelerated by human activities.