摘要
位于黄土高原与华北平原过渡带上的中原邙山黄土地层，以厚层Ｓ１古土壤（１５．７ｍ）和巨厚Ｌ１黄土（７７．３ｍ）为其特色。对赵下峪剖面Ｓ１０以上总厚１７２．１ｍ的黄土－古土壤序列的研究表明：（１）邙山黄土是一种风成近源砂黄土，其源区就在黄河下游冲积扇的扇顶部位；（２）约１５０ｋａＢ．Ｐ．（Ｌ２上部）开始，风尘沉积速率突然加快，Ｌ１ＬＬ１层段高达３．４５ｍｍ／ａ，其原因是黄河贯通三门峡东流给源区带来丰富的物质；（３）粒度和磁化率分别指示的冬季风与夏季风变迁存在四种强弱对应关系，与黄土高原的情况不完全一致；（４）邙山黄土－古土壤序列是黄土高原侵蚀与华北平原堆积的镜像反映。
Zhaoxiayu loess profile in Mangshan Yuan which is located at the transitional zone of the North China Plains and the Loess Plateau is a representative of the loess stratigraphy in China Central Plains.The loess paleosol sequence from S0 to S10,with total thickness of 172 1m,showing the B/M boundary at the top of S8,characterized by quite thick paleosol S 1(15 7m)and particularly thick loess L 1 (77 3m),is exposed from the surface of Mangshan Yuan downwards to the bed of Yellow River. This paper indicates:1)Mangshan loess is a kind of near source sandy dust deposit,the source area of which is just at the fanhead of the alluvial fan at the lower reaches of the Yellow River.2)Since 150ka B.P.(equivalent to the top of L 2)the dust sedimentation rate abruptly became bigger,and the average rate reached 3 45 mm/a in the late stade of the last glaciation.This is because the Yellow River has flowed eastwards through Sanmenxia Gorge at that time and transported abundant material to the area.3)In this area there are four corresponding relations between the variations of winter and summer monsoon,reflected respectively by grain size and magnetic susceptibility,which is incompletely consistent with that in Loess Plateau. Loess paleosol sequence at Mangshan not only records in detail the specific regional climate in response to the East Asian monsoon variations,but also clearly reflects an abrupt event in environment around 150kaBP.And since that time a united system of the energy and material exchanges between ocean and land has been formed,with the current of the Yellow River and monsoon circulation as conveying belt,linking the erosion in Loess Plateau and accumulation in North China Plain caused by tectonic movements,and having profoundly affected the natural environment of the Yellow River basin,even the area of Yellow Sea and Bohai Sea. It is also associated that loess paleosol sequences in Loess Plateau are not only the product or indication of the formation and evolution of East Asian monsoon,but also the outcome or record of the coupling effect between tectonics and climate.
出处
《海洋地质与第四纪地质》
CAS
CSCD
北大核心
1999年第1期45-51,共7页
Marine Geology & Quaternary Geology
基金
国家自然科学基金
原地质矿产部"九五"重点基础项目
国家攀登计划预选项目
关键词
黄土地层
构造运动
气候变化
耦合作用
古土壤
Mangshan loess tectonic movement climatic change coupling effect China Central Plains
