巴丹吉林沙漠全新世环境记录的年代校正与古气候重建

巴丹吉林沙漠地处东亚夏季风区的西北缘,是认识东亚季风演变及其区域响应的窗口。文章在系统研究前人工作的基础上,对环境记录的年代进行了新的校正,并重建了全新世环境演变的历史。分析结果显示,巴丹吉林沙漠在早全新世开始出现高湖面,早中全新世在湖区广泛出现高湖面和淡水环境并在沙漠东北缘发育了古土壤,晚全新世时湖泊水位下降,沉积地层以风成砂为主。巴丹吉林沙漠全新世环境变化总体上可分为3个阶段: 晚更新世末至早全新世初气候干旱; 在10.0cal.kaB.P.左右气候由干向湿快速变化,并在8.5~4.0cal.kaB.P.期间气候最为湿润,但同时存在短期的干湿波动; 4.0cal.kaB.P.以来气候总体干旱,但在2.2cal.kaB.P.左右出现短期的湿润。巴丹吉林沙漠全新世气候变化反映了该地区在早全新世东亚夏季风降水明显增强,中全新世季风降水较强,晚全新世季风降水减弱,同时具有短时期的不稳定性。10.0cal.kaB.P.以来巴丹吉林沙漠气候总体由湿润向干旱变化,应与北半球全新世以来太阳辐射的持续减弱有关。

REINTERPRETATION OF THE CHRONOLOGICAL DATA OF PALAEO-ENVIRONMENTAL RECORDS IN THE BADAIN JARAN DESERT AND RECONSTRUCTION OF THE HOLOCENE CLIMATIC CHANGES

The Badain Jaran Desert is located at the northwest margin of the East-Asian summer monsoon region and thus is a key area for understanding the changes of the East-Asian-Monsoon climate system and its regional responses.Based on an reinterpretation of the chronological data and palaeo-environmental records from previous palaeo-environmental studies in the Badain Jaran Desert and its neighboring regions,this paper aims to provide an updated reconstruction of the Holocene climate history in the middle portion of the desert belt in Northern China.Our results suggest that palaeolakes and palaeosoil developed since the early Holocene and maintained until the mid Holocene in the desert.The Holocene climate of the study area can be divided into three stages: 1)quite arid at the boundary between the Late Pleistocene and the beginning of the early Holocene; 2)and then quickly towards less arid environment at about 10.0cal.kaB.P. ,and reached the condition of the maximal moisture during 8.5~4.0cal.kaB.P. ,and with several short-lived episodes of increased dryness during this period; 3)generally arid climate since 4.0cal.kaB.P. ,but slightly wetter at about 2.2cal.kaB.P.This kind of trend indicates that the precipitation of the East-Asian summer monsoon was clearly enhanced at the Early Holocene,and kept relatively abundant during the middle Holocene but decreased drastically again in the Late Holocene.The Holocene climate history is characterized by repeated short-term instabilities.The fluctuations of Holocene climate in the region could be attributed to a certain degree to the changes of solar insolation in the North Hemisphere.