Abstract: Alluvial fan is a typical continental fan accumulation formed after the outflow of the river (flood). There are two kinds of sedimentary mechanism, the traction flow and the debris flow in the fan root area，which make the sedimentary model of alluvial fan complicated. The exposed alluvial fan phenomenon is well in Zhebu countryside, Laiyang city, Shandong province, which belongs to Cretaceous Wangshi group Xingezhuang Formation. Through the detailed observation and measurement on the section, using the sedimentary principle of the outcrop, the sedimentary environment was thought being an alluvial fan, which developed chaotic accumulation of conglomerate facies (Gms), massive bedding conglomerate facies (Gmh), trough cross bedding sandstone facies (St), planer cross bedding sandstone facies (Sp), horizontal bedding sandstones (Sh), floodplain mudstone (Fl) and massive bedding mudstone (M). The trough flow facies belt, slice flow facies belt, braid flow facies belt, runoff facies belt were identified. The facies of the trough flow belt and the slice flow facies belt were the least exposed, and the upper part of the main section was mostly debris flow deposits. The facies of the runoff facies and the braided flow facies were the most exposed, showing the characteristics of the interaction between sand and mud. In view of this, based on the study of the sedimentary characteristics of different facies zones, the sedimentary model was established and the evolution characteristics of the profile were analyzed combined with the outcrop characteristics of alluvial fan in Laiyang, Shandong province.

Key words: Alluvial fan, Outcrop, Sedimentary model, Evolution characteristics, Xingezhuang formation

摘要： 冲积扇是河（洪）流出山口后形成的典型陆相扇形堆积体。在扇根部位存在牵引流与碎屑流两种沉积机制，在扇中、扇缘两个部位则为牵引流沉积，使冲积扇内部沉积模式复杂。在山东省莱阳市近郊赭埠村发现了现象很好的冲积扇，属白垩统王氏群辛格庄组，通过对该剖面详细地观察与测量，运用沉积学原理对该露头进行解剖，共识别出了混乱堆积砾岩相、平行层理砾岩相、槽状交错层理砂岩相、板状交错层理砂岩相、平行层理砂岩相、水平层理泥岩相以及块状层理泥岩相。划分出了槽流相带、片流相带、辫流相带、径流相带，槽流相带与片流相带出露的最少，主要剖面的最上部多为泥石流沉积。而径流相带、辫流相带出露的最多，呈现出砂泥交互沉积的特征，可以清晰地识别出扇中部分近源辫状河的特征。结合山东莱阳冲积扇露头特征，通过对其不同相带沉积特征的研究，建立了其沉积模式并分析了剖面演化特征。

关键词: 冲积扇, 　露头, 　沉积模式, 　演化特征, 　辛格庄组