河套盆地第四纪沉积古地理特征及演化

Quaternary sedimentary paleogeography characteristics and evolution of Hetao Basin

通过对河套盆地1100条钻孔资料的岩性岩相综合分析,探讨了该区第四纪沉积相特征及古地理环境演变过程。研究认为:早更新世-中更新世早期,临河凹陷以湖泊沉积环境为主,三湖河凹陷以河流沉积环境为主,呼和凹陷为局限性河湖沉积环境,西山咀隆起与包头隆起都以古隆起剥蚀为主,全盆地沉积环境为局限性河湖,中更新世早期黄河已流入该盆地;中更新世晚期-晚更新世早期,全盆地形成了内陆封闭性咸水-半咸水湖盆,黄河为内流河;自晚更新世中晚期以后,随黄河逐渐外流,河套地区进入到准平原化过程,由湖泊沉积转为以冲积作用为主的河湖交替演化,最终以河流及山前冲洪积作用为主。晚第四纪河套盆地东西部沉积环境差异受区域构造及沉积古地理格局的控制。

According to the comprehensive analysis of lithology and lithofacies of 1100 drillings in Hetao Basin,the characteristics of Quaternary sedimentary facies and the evolution process of sedimentary palaeogeography environment were discussed.The conclusions are as follows.In the Early Pleistocene and the early stage of Middle Pleistocene,the paleogeography sedimentary feature of the whole basin where Linhe depression was dominated by lake sedimentary environment,Sanhuhe depression was dominated by river sedimentary environment,Huhe depression was a limited river and lake sedimentary environment,and both Xishanzui uplift and Baotou uplift were dominated by uplift-erosion,was a limited lake and river environment.The Yellow River flowed into the basin since the early stage of Middle Pleistocene.From the late stage of Middle Pleistocene to the early stage of Late Pleistocene,the whole basin formed an inland closed brackish water and saline water lake,and the Yellow River was an inland river.Since the middle and late stage of Late Pleistocene,the Hetao area entered a peneplain process with the gradual outflow of the Yellow River,where it reflected a fluvial-lacustrine alternative sedimentary environment mainly dominated by alluviation,and then there was mainly a river and alluvial-proluvial fan sedimentary environment.The difference of Late Quaternary sedimentary environment between the Eastern and Western Hetao Basin was controlled by regional structure and sedimentary palaeogeography frameworks.