新疆准噶尔盆地西缘白杨河扇形地边缘沉积分析

依据新疆地区西准噶尔山地白杨河中游山前冲洪积扇缘沉积物剖面，分析了第四纪中晚期扇缘沉积结构，对沉积环境尤其是与沉积相关的水动力条件进行了分析与探讨．研究表明，沉积物自上而下分为5个沉积阶段．全部11个样品中的5个样品具有双峰式粒度分布，其中一个样品为3峰式．主峰粒度位于2．5φ，次峰在-3．5φ，-2．5φ，第三峰位于4φ．主峰代表弱水动力环境，次峰代表强水动力环境，第三峰接近静水环境，属于扇缘湖相环境．样品粒度的多峰式特征是干旱区山前洪水对不同粒级颗粒的搬运及沉积，或洪水期后较弱的水流所搬运的细颗粒物质对洪流阶段较粗颗粒沉积的填隙．受山前地貌影响，洪水期后扇缘附近洼地积水是第三峰出现的地貌环境原因．

Sediment Dynamic Analysis on the Fan Edge of Baiyang River in the Western of Junggar Basin,Xinjiang Province

The sediment structure middle Baiyang River in the western of Junggar Basin was analyzed according to its deposition on the alluvail fan edge of Middle-late Quaternary, and the sedimentary environment was also discussed, especially for the hydrodynamic condition which was related to deposit. The results showed that there existed five stages of deposition from top to bottom. Four of all the total eleven samples have a bimodal type and one of these samples has 3 peaks type particle size distribution. The particle size of main peak is 2.5φ , the Secondary is -3.5φ or -2. 5φ, and the Third is 4φ. The sediment dynamics of the main peak is weak ,while the Secondary peak represents a strong hydrodynamic environment, and the Third peak is close to the hydrostat- ic environment, which belongs to the fan edge lacustrine environment. The causes of the multimodal character- istics of the sample size were that flood water handling interstitial torrent stage coarse particles deposited in the arid region , or flood became weaker and the fractions fine particulate matter deposited after handling the coarse particulate matter. The conformation of the Third peak was the water of depressions accumulation on the allu- vail fan edge.