塔里木盆地南缘尼雅剖面的孢粉组合与环境

Pollen assemblages of Niya section in southern Xinjiang and paleoenvironmental evolution

根据尼雅剖面孢粉含量的分析 ,结合 14 C年代、δ13C和低频磁化率 Xlf值的变化 ,探讨了位于塔克拉玛干沙漠南缘尼雅地区近 40 0 0年来的气候环境演化。结果表明 ,近 40 0 0年来 ,此地区气候持续干旱 ,但期间仍有几次相对湿润的波动 ,即在约 360 0 a BP前后 (1 650 BC)、2 50 0～ 1 90 0 a BP(550 BC～ 50 AD)和 1 40 0～ 1 0 0 0 a BP(550～ 950 AD)期间 ,生态环境湿润程度有所增加。研究还表明 ,干旱区孢粉分析结果对于古植被、古气候环境的恢复以及古人类活动变迁的推测可提供较为有用的信息 ,剖面中 1 .70～ 1 .60 m (1 0 0 BC～ 50 AD)

Based on the pollen analyses of Niya section which is located at southern margin of the Tarim Basin, this paper probes into the paleoenvironmental evolution during historical times (since about 4 000 a BP) in this district. The paleoenvironmental information stored in pollen assemblage coincides with that revealed by other geological indices, such as the ratio of geo chemical element, low frequency susceptibility and δ 13 C. The results show three relative humid periodes has been identified, i.e., about 3 600 a BP (1 650 BC), 2 500~1 900 a BP (550 BC^50 AD) and 1 400~1 000 a BP (550~950 AD), although the macro background of drought consecutively existed. This paper also reflects that (1) studies of pollen assemblage of arid area provide useful information on paleoenvironmental changes; (2) the two abnormal high values of Gramineae appeared at 1 70~1 60 m (100 BC^50 AD) in this section imply intensified human agricultural activities during this period; (3) what's more interesting is this period incarnates apparent relative humidity reflected by pollen data and other indices.