摘要
浑善达克沙地周缘及腹地质量磁化率的测定和粒度分析表明 :区域上粒度变化表现为东部较西部粗 ,腹地较周缘粗 ,南部较北部粗的规律 ,说明粒径的大小及土壤的成壤与源区及地表环境有关 ,同时也说明了浑善达克沙地的形成过程受东亚季风变化的影响 ;时间上 ,末次冰期晚期 ,浑善达克沙地全面扩张 ,主要表现为现代草场的位置都可找到古风成砂 ;冰后期 ,浑善达克沙地成壤作用较好 ,这个时期属于一个大的成壤期 ,即使在沙地的腹地也成壤 ;目前该地区处于成壤期 ,但成壤作用比冰后期差 ,粘土含量减少 ,地表粗化现象严重 。
For the sake of the fully understanding of the environmental features of the Otindag Sandy Land of Inner Mongolia Autonomous Region, China,five typical sections of the sand area were selected and studied by the author of this paper. Three of them are in the southern border and the other two are in the hinterland and northern border respectively. For obtaining the new information about the desertification of the whole Otindag Sandy Land area in different regions and different periods, we collected two hundred and seven sedimentary samples at intervals of 5cm or 10cm and measured their granularity and the quality susceptibility. By comparing the measured data, it shous that the paleo aeolian sands are the mark of the movement and expansion of the desert; paleosol is the mark of the stablization and contract of the desert and also the product of the action of pedogenesis on paleo aeolian sand. The present environment condition was studied by searching for the record of the surface sand. Fig.3 shows that the curves of grian size data(the mean, <60μm(%)) and susceptibility value can be subdivided into three part ranging from the bottom to the top. On the basis of the field work and quality susceptibility value and grain size characteristics analyzing, the following conclusions can be drawn: (1) the grain size of the east area is coarser than that of the west area; the grain size of the north area is coarser than that of the south area. What is more, the grain size of the hinterland is much coarser than that of the border area, which indicates that the grain size has much relation on the provenance and subaerial environment and the forming process of the Otindang sandy land was mainly influenced by East Asia monsoon. (2) As time went on, it shows that the Otindag Sandy Land had been expanding during the last glaciation, and which can be testified by paleo aeolian sands in the section. The postglacial age was the best period of pedogenesis in the whole Otindag sandy land. At the present, though not as typical as
出处
《干旱区地理》
CSCD
北大核心
2003年第3期233-238,共6页
Arid Land Geography
基金
国土资源部地质调查局"中国三北荒漠化区域分类与发展趋势研究项目 ( 2 0 0 0 112 3 0 0 0 0 4)"
黄土与第四纪地质国家重点实验室项目 (SKLLQG0 3 0 8)资助
关键词
浑善达克沙地
粒度
环境记录
磁化率
末次冰期
Otindag sandy land
grain size composition
quality suceptibility
environmental record.
