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科尔沁和浑善达克沙地周边沉积了中国东北地区目前已知的保存完好、沉积年代最久远的黄土,是研究区域干旱化过程和沙地演化的理想材料。通过对内蒙古自治区赤峰市附近约1.08 Ma以来约60m厚黄土剖面的高分辨率粒度分析,发现该地区黄土具有典型风成沉积特征,并且其沉积过程受东亚季风在冰期-间冰期周期性变化影响。由于距离粉尘源区较近,这些黄土序列记录了中更新世以来冬季风增强导致的源区沙漠/沙地的阶段性干旱化和发生于~670ka和~943ka的两次沙漠/沙地扩张事件。新揭示的干旱化事件与中国西部-中部的环境演变过程一致,可能是中更新世气候转型时期阶段性全球冰量增加、温度降低驱动中国东北地区更新世气候演化的结果。
Surrounding the Horqin and Hunshandake Sands, the most well-preserved and oldest loess deposits in northeastern China have been deposited and are ideal for studying the process of aridification and evolution of sand in the area. Through the high resolution grain size analysis of the loess section about 60 m thick since about 1.08 Ma near Chifeng City, Inner Mongolia Autonomous Region, it is found that the loess has typical characteristics of aeolian deposition and the sedimentary process is affected by the periodic variation of East Asian monsoon during glacial-interglacial period . Due to the proximity to the dust source, these loess sequences record the staged aridification of desert / sandy areas in the source area and the two desert / sand expansion events occurring between ~ 670 ka and ~ 943 ka since the mid-Pleistocene winter monsoon enhancement . The newly revealed drought event is consistent with the environmental evolution in the western part of China and the central part of China. This may be the result of the global increase in the amount of ice and the temperature decrease in the mid-Pleistocene climatic transition that led to the climate change in the Pleistocene climate in Northeast China.