【摘要】 中国西北干旱区有大面积的戈壁地貌,但对其形成过程的研究不多。阿尔金山北缘的沉积物记录着临近戈壁地貌的发育过程。选择甘肃敦煌南湖绿洲附近的山水沟剖面作为研究对象,在独立的光释光测年基础上,通过对比分析粒度特征、磁化率和有机碳同位素值变化,探讨5ka BP以来阿尔金山北缘戈壁沉积动力过程及其环境控制因素。结果表明:戈壁发育进程具有波动性,戈壁沉积动力在百(千)年时间尺度上受到环境因素制约,在2.67~3.57ka BP和1.65~1.95ka BP干热气候条件下,沉积物搬运动力较弱,戈壁发育受限;在4.27~4.84ka BP时期水量较大,戈壁发育范围较广,属于扩张阶段。这一结果初步揭示了戈壁地貌演化与气候环境变化的联系。更多还原

【Abstract】 Gobi desert covers a large area of northwestern China,but few studies are undertaken on its formation and evolution.Palaeoenvironmental change of the Gobi deserts in front of Northern Altun Mountains are recorded by alluvial deposits.Based on optically stimulated luminescence(OSL)dating the Shanshuigou section record which is close to the Nan Hu oasis of Dunhuang in Gansu province,as well as investigations such as grain size,magnetic susceptibility and organic carbon isotopic composition,the Gobi depositional environment variation since in 5 000 yrs BP was examined.Results show that the evolution of the Gobi deserts are of fluctuation and the sedimentary dynamics are affected by climatic change at centennial to millennial time scales.Sediment transport capacity was weaker during 2 670-3 570 yrs BP and 1 650-1 950 yrs BP because of the dry and warm climate,and thus the Gobi desert was shrunk.On the other hand,the transported processes were enhanced as a result of increased river discharge during 4 270-4 840 yrs BP.These results unravel the linkage between landform evolution of the Gobi deserts and climatic change during the late Holocene.更多还原