贺兰山西麓第四纪沉积与环境演变

QUATERARY DEPOSIT AND ENVIRONMENT EVOLUTION ON THE WESTERN PART OF THE HELAN MOUNTAIN

本文根据沉积模式对比研究,确认贺兰山山前混杂堆积为泥石流沉积。据下更新统孢粉分析,早更新世山地植被同东部有较多联系,平原区有两个以草本为主及两个以灌木为主的植被演化阶段,所反映的古气候为干冷及温干的交替;与地层相对应,冷期有巨砾层形成,温干期形成粘土砾石层。晚更新世、全新世有多雨气候波动,腾格里沙漠中成百的湖泊分布,成因与此有关。

Based on the comparative studies on the model of deposit, the paperdetermines that the mixture piling up in front of the Helan Mountain is ofdebris flow deposit. Analyses of the sporopollen in the low Pleistocene seriesshow that in early Pleistocence epoch, the vegetations on the mountain hadmuch to do with those on the eastern part of the mountain. The paper indica-tes the four great changes of vegetation evolution happened in this area. Thestudy shows that the paleoclimate at the time alternately appeared to be dry-cold and warm-dry. As for strata there are indications that the gravel layerwas formed in the dry-cold period while the clay-gravel layer was formed inthe warm-dry period. The study points out that the epoch of late PleistoceneandH clocepe, the climate was wet, rainy and changable, which can wellexplain the formation of hundreds of lakes distributed in the Tenggeli Desert.