The thesis draws the following conclusion : ( 1 ) 11500 - 8500ab . p . , through comprehensive analysis of these proxy climatic substitute indexes reveals : this was a period in which the temperature risen and the precipitation increased , but it was mainly still dry and cold ; the vegetation was prairie or forest prairie ; there were flood deposits in the dust sediments of late stage ; and it was the shifting period from the new stone age to the old stone age 主要得到以下几方面的认识： ( 1 ) 11500 8500ab . p . ,综合多气候代用指标分析的结果表明：本期气候表现为温度升高、降水增大的好转时期，但总体上仍以干冷为主；结合很少发现较粗颗粒木炭屑的情况推断当时的植被是草原或森林草原；研究发现在后期粉尘沉积过程中有洪流沉积。
O curve of dsdp607 v30 - 97 show that loess began to deposit on the terrace of the yellow river about 1 . 20 ma b p , and passed thirteen climatic changes from drier and cooler to warmer and wetter later . the turn of sedimentation from alluvium to loess , an event of transformation from accumulation to down - cut of the yellow river , indicates a sharp tectonic uplift occurred around 1 . 2 ma b p . key words : loess - paleosol ; susceptibility ; climatic changes ; tectonic movement ; yellow river ; yangfan section 通过对杨范剖面黄土地层岩性特征沉积结构质量磁化率和频率磁化率的分析及与深海氧同位素曲线的对比，划分了剖面地层，初步确定了黄土沉积始于1 . 20 ma b p ,黄土沉积以来该区发生了13次大的干冷暖湿气候变化沉积转型指示河流强烈加积转变为河流侵蚀，代表约在1 . 20 ma b p发生过一次强烈的构造抬升事件。
