1.08Ma以来中国东北赤峰地区黄土粒度变化及其揭示的沙地扩张事件  

Evolution of Horqin and Otindag Dune Fields since 1.08 Ma Recorded by Grain Size of Loess in Chifeng,Northeastern China

作　　者：吕安琪[1] 鹿化煜[1,2] 曾琳[1] 弋双文[1] 卓海昕[1] 徐志伟[1] 张文超[1] 

机构地区：[1]南京大学地理与海洋科学学院,江苏南京210023 [2]中国科学院青藏高原地球科学卓越创新中心,北京100101

出　　处：《中国沙漠》2017年第4期659-665,共7页Journal of Desert Research

基　　金：国家自然科学基金重大项目(41690111);国家重点研发计划项目(2016YFA0600503;2016YFE0109500)

摘　　要：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。Extensive loess deposits that mantle on various landscapes are found in the adjacent areas of the Horqin and Otindag dune fields,which should record the aridificaion history and desert evolution in Northeastern China.Here,we present a high-resolution grain-size analysis of a 59.9-m-thick loess-paleosol sequence in the south margin of Horqin and Otindag sand fields that covers the ca.1.08 Myr（1 080 kyr）.The grain-size distribution of these loess deposits shows typical features of aeolian deposits,and records the cyclical variations of the East Asian winter monsoon and dune fields during glacial-interglacial cycles.It also demonstrates a long-term drying trend caused by the strengthening East Asian winter monsoon in Northeastern China since ca.1.08 Ma.The Horqin and Otindag dune fields expanded in ca.670 ka and ca.943 ka.These drying events correspond with other records in the western and central China.It may reflect that the increase of northern hemisphere ice volume and global cooling should have forced the stepwise aridification and caused dune field extension to the Southeast China since the Mid-Pleistocene Transition Event.

关 键 词：中国东北 科尔沁沙地 浑善达克沙地 黄土 粒度 冬季风 

分 类 号：P531[天文地球—古生物学与地层学]