末次间冰期以来西宁市河谷沉积与环境  

DEPOSITION IN XINING RIVER VALLEY AND ITS BEARING ON ENVIRONMENTAL CHARACTER SINCE THE LAST INTERGLACIAL PERIOD

作　　者：王萍[1] 蒋汉朝[2] 苏旭[3] 严富华[1] 

机构地区：[1]中国地震局地质研究所、中国地震局地震动力学国家重点实验室,北京100029 [2]中国科学院地质与地球物理研究所,北京100029 [3]青海省地震局,西宁810000

出　　处：《第四纪研究》2008年第2期253-263,共11页Quaternary Sciences

基　　金：国家自然科学基金项目(批准号:40472090);中国地震局“十五”重点项目(中国地震活断层探测技术系统--西宁市地震活动断层探测与地震危险性评价)(批准号:1-4-29)资助

摘　　要：在西宁市区开展的钻探工作,获得了河谷平原区第四系的分布及沉积特征。通过对沉积厚度最大部位的2个钻孔岩芯的地层岩性、年代测试、孢粉组合及粒度分析等,探讨了西宁河谷平原区晚第四纪沉积与环境的关系。认为现今西宁市河谷平原内的主体沉积——低阶地沉积及上覆黄土堆积主要是末次间冰期旋回形成,在暖湿气候条件下沉积河流相砂砾石层,在干冷气候期接受风成黄土堆积,推测T3阶地形成于距今7.4万年前后气候由暖湿向干冷的过渡时期。Quaternary distribution and sedimentation of the Xining river analysis. Discussion on the relationship between the Late Quaternary valley plain were investigated by drilling deposition and environmental changes was carried out based on analyzing the stratigraphic lithology, OSL age, pollen and grain size of two cores from the thickest depositional sites. The results indicate that the main sediment in the present Xining river valley plain, mainly including lower terraces and overlying loess, has deposited since the last interglacial period. The maximum River and its distributary. Their vertical falls are 2 - 4m, 12 - 14m, and 23 - 30m, respectively. The fluvial sand and gravel were deposited when the climate was warm and humid, during interglacial or interstadial periods, and the subsequent aeolian loess was deposited on the terraces during dry and cool period. Accordingly, T3 was formed at the climatic transition, about 74ka. Nevertheless, the detailed process of terrace formation and its correlation to other regions need further investigation.

关 键 词：末次间冰期 河流阶地 钻探岩芯 光释光年龄 西宁 

分 类 号：P534.63[天文地球—第四纪地质学] P546[天文地球—古生物学与地层学]