【摘要】 本文概述了鄂尔多斯高第三系至全新统地层中融冻(衤习)皱和沙(土)楔两类古冰縁现象的分布与形态特征,探索了它们的成因以及同所在地层和上覆风成沙或黄土的关系,並对古冰縁现象的气候地层学意义作了讨论。更多还原

【Abstract】 At the present time two kinds of fossil ice margins have been found, con-gelifolds and fossils sand (loess) wedges in the strata of the studied area. The former is mainly found in the limnetic strata at the top of the Salawusu Group(Q31), The middle Chengchuan Group (Q32-2), The middle and the lower Dagouwan Group (Q43) and at the bottom of Dishaogouwan Group (Q43) along the Salawusu He in the southeastern depression Among them the middle Chengchuan Group is the largest and the widest.Besider, it can also be found in certain horizons along the wuding He, Lu He, Hailuitu He, yulin He and Salawusu He near the loess hilly areas. The latter is mainly presented in the Tertiary mud stone or red earth, in the lower-middle Pleistocene loess or the lower part of the late Pleistocene sand (earth) gravel layer and on the top of the middle Chengchuan Group in the central-western dry denuded upland and the flat and lower areas on the low ridge land of its extending part to the depression.According to the morphological characteristics of the profile, these folds and wedges had not any relation to the genesis of tectonic movement fluvial-erosion, accumulation, glacier, mudflow, hard press of landslide and drying crack of ground surface, but to the stratum deformation or disturbance caused by seasonal nonhomogeneous melting and freezing processes for a long time in the frozen eartn area.The big or medium type of nondeveloped congeli-folds (mainly situated in the upper late pleistocene strata) and sand (loess) wedges(situated in the middle and lower profile)were related to the seasonal process of the permafrost and the other congelifolds located in the middle and lower Holocene strata and the small type of sand (loess) wedges located in the upper profile might possibly be formed under the condition of the deep seasonal frozen earth and even the other year’s frozen earth.According to the relation of the phenomenon of fossil ice margins with the existing horizon and the physterogenetic or contemporaneous association of over-rlying eolian sand or loess, and referring to the measured data of absolute age of the strata concerned, it is roughly determined that the congelifolds on the top of the Salawusu Group, in the middle Chengchuan Group, the middle and lower Dagouwan Groop and at the bottom of Dishaogouwan Group were formed at the early and late sections of the late stage of the late pleistocene of 70,000 and 25,000 years B.P.and the mid-late stage and at the beginning of the late stage of the Holocene of 5000 years or 3200 years and 2300 years B.P.respectively, the situation of sand (loess) wedges was very similar to the above-mentioned situation.These periods correspond to the early Yumu glacial epoch, the late Yumu glacial epoch and the beginning of new glacial epoch and the small glacial epoch.It shows that during these periods the studied area was influenced by the fluctuation of cold weather of the four glacial epochs of the Northern Hemisphere.The above-mentioned data of fossil ice margins have provided new reliable evidences for the reconstruction of the ancient climatic environment, the division of climatic strata, the comparison and the prode in the genesis in the study area since late pleistocene.The study suggests that the study area at the early and late sections of the late stage of late pleistocene and the mid and late Holocene or late Holocene was island-like permafrost and deep seasonal frozen earth or the other yearxs frozen earth area at the southern periphery of the continuous permafrost zone,the climate then was generally dry and cold and there was much northwest wind;eolian sand or loess and the deposition of fluviolacustrine facies or fossil soil belonged to the products of dry and cold ice margins or near ice margin environment and warm wet non-ice margin environment respectively, since late pleistocene the study area had undergonemany times of climatic fluctuation of the replacement of ice margin of warm wet facies with that of dry cold facies.The main cause was that the study area was situated in the transitional更多还原