兰州最老黄土剖面的岩石、粒度、孢粉、沉积模式等特征  

The characteristics of rock, grain-size, sporo-pollen and depositional model in the oldest loess section in Lanzhou

作　　者：张有龙[1] 周伶琦 张维雄 石文礼 

机构地区：[1]中国地震局兰州地震研究所,甘肃兰州730000 [2]甘肃地调院第三地质矿产调查所,甘肃兰州730050

出　　处：《西北地质》2003年第3期29-37,共9页Northwestern Geology

基　　金：1:5万<通远乡幅>;<苏家峡幅>区调项目

摘　　要：兰州北部永登县地沟村山城湾岭剖面发现兰州地区迄今为止最老的黄土沉积,形成于1.84Ma.BP;有18个完整的黄土-古土壤序列;黄土平均粒度为23.57μm,古土壤为19.10μm,黄土主要由粉砂粒组组成;草本花粉占90%以上;总结了黄土成因及沉积模式;对比确定了上、下粉砂层的层位。The oldest loess deposits in Lanzhou area, formed 1.84 Ma.BP ago, was recognized for the first time in the Shanchengwanling Section, Digou village, Yongdeng county, North of Lanzhou. It has eighteen integral sequences of loess-paleosol. The average grain-sizes of loess are 23.57 μm, and of paleosol is 19.10 μm. The loess is composed of siltstone and 90% grass-flower flours in sporo-pollen assemblage. On the basis of field survey and indoor systermatic study, the authors summarized the genesis of loess and depositional model, determined the location of up and down siltstone layers through stratigraphic correlation.

关 键 词：兰州 磁性地层 孢粉 黄土 地层对比 

分 类 号：P642.131[天文地球—工程地质学]