新疆伊犁河谷风沙沉积晚全新世孢粉记录及气候变化

 通过地处亚洲中部干旱区的新疆伊犁河谷塔克尔莫乎尔沙漠沉积剖面(TKP)73块孢粉样品的鉴定分析,结合光释光(OSL)测年数据,获取了TKP沉积剖面晚全新世(约3.78~0 ka BP)植被变化特征与古气候历史。TKP剖面孢粉资料揭示出该研究区3.7 ka BP以来经历了多次的气候干湿波动,大致以2.2 ka BP为界,分为前后两个时期,前期孢粉总浓度较低,平均仅有5粒·g-1,主体表现为沙漠,气候整体干旱; 后期孢粉总浓度明显增加,平均为85粒·g-1,为荒漠植被,并存在4个相对干湿的变化阶段; 最近0.3 ka BP以来,孢粉总浓度并不十分丰富(33粒·g-1),整体表现变干的趋势。TKP剖面孢粉资料反映的晚全新世干湿波动与其他相邻区域具有较好的可比性,具有区域一致性特征。在小冰期时TKP剖面表现为冷湿的气候特征,有可能是受到中高纬度北大西洋气候变化的影响。

Late Holocene Climate and Environment Changes Inferred from Pollen Recorded in Takelmukul Desert in Yili Valley of Xinjiang,China

Based on the pollen analysis on a desert sediment profile in Yili valley of Xinjiang, combined with optically stimulated luminescence ages, the characteristics of paleovegetation and paleoclimate evolution since 3.7 ka BP were reconstructed. The record reveals that the study area has experienced alternations of relative arid and wet and could be divided into two stages before and after 2.2 ka BP. In the first stage (3.7~2.2 ka BP), the total concentration of pollen is very barren by an average of 5 grains·g-1, and indicates a relatively arid desert climate; in the latter phase (2.2~0.3 ka BP), the total concentration of pollen significantly increases by an average of 85 grains·g-1, and suggests a relative wet climate as a whole. The latter stage can also be divided into four relatively wet and dry sub-stages. The total concentration of pollen is relatively low (33 grains·g-1) during the last 0.3 ka, and it shows a relatively dry climate. The climate changes in the research area agree well with that of neighboring regions. The record indicates a lower temperature and humid climate during the Little Ice Age within the study area, and the cooling of the north Atlantic may exerts important influence on the climate change in arid central Asia.