黄土高原黄土地层分区及其地层结构

On the Division of Stratigraphical Region of Loess Plateau

黄土地层序列同黄土地貌分区有成因上的联系,不同成因的地貌环境其黄土地层结构不同.依据地貌区划结合黄土地层特征可将黄土高原黄土地层划分为以下四个主要分区:1.梁峁地层区.该区又可分为六盘山以西及以东两个亚区;2.源地层区.又可细分为塬亚区.台塬亚区及山麓塬亚区;3.山间盆地地层区;4.河谷地层区。

The stratigraphical sequence of the Loess plateau is closely related to the geomorphologic locality. The sequence differs as to where the strata are located. According to the geomorphologic regions and the characters of stratigraphical sequence, the stratigraphical sequence of the loess in China may be divided into the following stratigraphical regions: 1.Liang-Mao stratigraphical region may be divided into two parts:(1) The west Liang-Mao stratigraphical region:most great thickness of loess; relatively coarse; pale colour; less fossil and concretion; hardly discernibleness of paleosol. (2)The east Liang-Mao stratigraphical region: greater thickness and becoming thinner and thinner to eastward; abundant coarse particle, especially in the central part; there are many interealations of wind-drift sandy beds; less fossils; the dark loam is black and thick. 2. The Yuan stratigraphical region may be divided into: (1)Yuan subregion, (2) Taiyuan subregion, (3)Pediment subregion. The loess system in this region carries the following characteristics: The stratigraphical development is complete; stratigraphical sequence of all the places are alike; abundant mammalian fossils; contains two sandy silt layers; the uper strata are basically of the same thickness in various places, but the lower parts are different in thickness as to where it is; paleosol clearly visible. 3. The mountainous basin stratigraphical region: abundant mammalian fossils; the tops of strata of different times were denuded, some strata are inclined and intersected each other. 4. The valley stratigraphical region: paleosol evident; the older the terrace, the more complete the strata; the loess is overlying on terraces like mantles.