利用光释光测年技术对科尔沁沙地的7个风成砂-砂质古土壤剖面进行年代测试,结合地层和孢粉分析得到晚冰期以来科尔沁沙地的演化过程如下:16~10 ka B.P.,风成砂出现,沙地活化;10~3 ka B.P.,砂质古土壤发育,沙地固定;约3 ka B.P.前后,风成砂出现,沙地活化;3 ka B.P.至今,多层弱发育砂质古土壤和风成砂的交替出现,指示晚全新世科尔沁沙地的多次固定与活化;从约4~2 ka B.P.,沙地环境由草甸草原逐渐退化为典型草原。分析表明,3 ka B.P.以前科尔沁沙地的演化完全受气候变化的控制,之后(尤其是辽代以后)人类活动的影响日益增强。
The Horqin dunefield is located in the northern frontier of East Asian Monsoon (EAM) zone, and its activation and stabilization is sensitive to the ebb and flow of the EAM. However, the activity of dunes in the Horqin dunefield is still poorly understood due to the limited numerical dating. The purpose of the present study is to explore the dune evolution using luminescence dating and pollen analysis in order to understand the relative role of climate and human activity. In the present study, 21 samples collected from seven sections in the Horqin dunefield were dated using quartz optically stimulated luminescence (OSL) dating method. Combined with the stratigraphy, pollen materials and the OSL chronology, the dune avolution in the Horqin dunefield since the late glacial period can be summarized that before 16-10 ka B.P., aeolian sand dunes were mobilized; during 10-3 ka B.P., dunes were stabilized, with dark sandy soil development; at around 3 ka B.P., dunes were mobilized again abruptly; since 3 ka B.P., there were multiple phases of dune stabilization/mobilization. Between 4 and 2 ka B.P., the vegetation of Horqin dunefield degenerated gradually from the meadow steppe to steppe. Dune activity was dominated by climate before 3 ka B.P. However, since 3 ka B.P., both climate variability and human impact have influenced dune evolution in the Horqin dunefield.
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