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通过对吕梁山前(西)山西保德剖面和柳林剖面的野外考察,结合前人研究成果,研究了新近纪地层的组成及空间分布。新近纪地层自下而上可以分为三段:下段为水成砂砾石层,上段为风尘堆积的红粘土,中部则为二者的过渡带。柳林剖面的详细研究揭示了水成堆积物与红粘土的细部特征:粗粒的砾岩和砂岩常切穿红粘土层,而粒度与红粘土相近的泥岩则常与红粘土平行产出。野外调查结合区域资料分析表明新近系各组成成分空间分布具有明显的规律性:靠近吕梁山(保德剖面)下部水成堆积物粒度较粗且厚度较大,红粘土厚度相对较薄;背离吕梁山下部水成堆积物逐渐变细且厚度减薄(柳林剖面、府谷剖面)直至尖灭(佳县剖面),与之伴生的是红粘土厚度逐渐增大;中间过渡带中水成堆积物与红粘土的比例与此相似,即区域上吕梁山前的水成堆积物呈楔状“侵入”于红粘土的中下部。红粘土与水成堆积物的关系的确立为更好的理解红粘土的成因、吕梁山的新生代隆升历史及恢复新近纪晚期的古气候演变具有重要意义。
Based on the field investigation of the Baode section of Shanxi Lüliang Mountain (west) Shanxi Province and the section of Liulin, combined with the previous research results, the composition and spatial distribution of Neogene strata are studied. The Neogene strata can be divided into three sections from the bottom up: the lower part is a water-filled gravel layer, the upper part is a dust-accumulated red clay, and the middle part is a transition zone between the two. A detailed study of the Liulin section reveals the detailed features of the water deposits and red clay: coarse-grained conglomerates and sandstones often cut through the red-clay layer, whereas mudstones similar in size to red clay often yield parallel to the red clay. Field investigation and analysis of regional data show that the spatial distribution of each component in the Neogene is obviously regular. The water sediment near the Lüliangshan (Baode section) is coarse and thick with relatively thin red clay. The sediments of the lower part of the mountain water become thinner and thinner (Liuliashan profile and Fugu profile) till pinnacle (Jiaxian profile), accompanied by the gradual increase of the thickness of the red clay; the water accumulation in the intermediate transitional zone The ratio of material to red clay is similar to this, ie, the water accumulation in front of Luliang Hill in the area is wedge-shaped “invaded” in the middle and lower parts of the red clay. The establishment of the relationship between red clay and water deposits is of great significance in order to better understand the origin of red clay, the history of Cenozoic uplift of Lvliang Mountain, and the restoration of paleoclimate evolution in the late Neogene.