中国科学院研究生院学报2002，Vol.19Issue(2)：202-208,7.
晚中新世以来中国北方风成沉积的磁性地层学和沉积学研究及其古气候意义
Magnetostratigraphy and Sedimentology of the Eolian Deposits Since the Late Miocene in Northern China and the Paleoclimatic Implications
摘要
Abstract
In this study, two thick loess-red clay sequences located at Lingtai and Jingchuan, theChinese Loess Plateau, are studied with emphases on magnetostratigraphy and sedimentology. Paleo-magnetic measurements show that the Jingchuan red clay has a basal age of 8.0 Ma, which is one mil-lion years older than the previously studied Lingtai section. Field observations and grain size analysesboth suggest an eolian origin of the red clay sediments at Lingtai and Jingchuan, thus extending avail-able records of the eolian deposits in the Loess Plateau from 2.6 Ma back to 7.0 ～ 8.0 Ma. Correla-tion of five red clay sections in the Loess Plateau suggests that the Lingtai red clay sequence has a rel-atively continuous nature of sedimentation and can be regarded as the type-section of the Tertiary redclay deposits in northern China. On the basis of spatial changes in the grain size of one northwest-southeast loess transect, several semiquantitative models of grain size parameters versus the minimumdistance from the source region to depositional areas were developed. According to these models, theestimated southeastern margin of the desert in northern China during the Tertiary red clay developmentis similar to that of the present Badain Jaran desert. To reconstruct the long-term East-Asia monsoonhistory from the celebrating eolian red clay-loess deposits, the ratios of CBD-extractable Fe2O3to totalFe2O3 concentrations in the Lintai red clay-loess sequence, the proxy indicator for the summer mon-soon changes, were measured. The Lingtai Fe2 O3 ratio record indicates that the East-Asia summermonsoon has experienced a non-linear evolution over the past seven million years. The strongest EastAsia summer monsoon may occur between 4.1 and 4.8 Ma, which may be causally related to the rela-tively small ice volume and high global temperature during the early Pliocene.关键词
黄土/红粘土/风成沉积/粒度/古季风Key words
loess/red clay/eolian deposits/grain size/paleomonsoon分类
天文与地球科学引用本文复制引用
杨石岭,丁仲礼..晚中新世以来中国北方风成沉积的磁性地层学和沉积学研究及其古气候意义[J].中国科学院研究生院学报,2002,19(2):202-208,7.基金项目
supported by the National Natural Science Foundation of China (40024202). （40024202）
