野外调查和前人资料表明吕梁山前新生代砾石层特征如下:(1)平行于吕梁山方向砾石层延伸很长,基本与吕梁山如影相随,垂直于吕梁山方向延伸不远,一般不越过晋陕谷地;(2)砾石层在东西向剖面上呈东厚西薄不对称楔形,砾石粒径自吕梁山往外逐渐变细,分选性和磨圆度提高。(3)各地砾石相对单一但因地而异,主要来自毗邻的吕梁山基岩。砾石层空间分布特征、砾石成份与毗邻基岩区耦合关系及典型剖面沉积学研究表明,砾石层是吕梁山前冲积扇相堆积,是吕梁山新生代隆升剥蚀产物,非南北向黄河阶地堆积物。
Field investigation and previous studies about the Cenozoic gravel beds in the piedmont of Lüliang Mountains have indicated that these gravel beds are characterized by the following: (1) The gravel beds, which always go with Lüliang Mountains but scarcely go beyond the Huanghe (Yellow) River valley, extend further in parallel than in vertical direction of the mountains. (2) The gravel beds show a asymmetric wedge shape (thicker in the east) in E-W direction, and have smaller granularity, better gradation and psephicity in the west. (3) The composition of gravels is relatively unitary but varying in the different locations. It is originated mainly from the bedrock in the adjacent Lüliang Mountains. Based on the study of spatial distribution of the gravel beds, adjacent bedrock's composition and typical profile sedimentology, this paper suggest that the gravel beds could be treated as deposits of alluvial fan facies resulted from Lüliang Mountains's Uplift in Cenozoic Era rather than the terrace accumulation of the Huanghe River in S-N direction.
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