【摘要】 第四纪时期在鄂尔多斯块体上所堆积的黄土系列沉积,是为特殊气候环境所形成.其周围断陷盆地内,下部为河湖相沉积,上部为黄土类沉积、区内上新世红粘土沉积后出现的侵蚀面,是第三纪和第四纪分界界面标志.又据古地磁资料,第四纪底界时代为300万年左右.更多还原

【Abstract】 A series of loess accumulations formed in some special climatic environments, distributed widely in the Eerduose block in Quaternary, but during the same time a lot of fluvial-lacustrine deposits were accumulated in the adja-cent block basins. This clearly shows the differences between tectonic develop-ments and climatic evolutions.A erosional surfac?was formed after red-clay has been deposited in the whole area. This surface can be served as a very, clear boundary between Ter-tiary and Quaternary. According to correla-tions of palaeomagnetic data, the fluvial-lacustrine deposits of Nihewan Formation (Sanman Formation) should belong to Lower Quaternary strata, with a bottom age at about 300m. y. B. P.更多还原