摘要
新疆和黄河中游地区中晚更新世以来56个样品的热释光年龄测定结果表明:新疆黄土保存较好的地层剖面是在距今40×10~4a前开始堆积的,其黄土/古土壤系列可以和黄河中游地区对比;黄河中游各地马兰黄土底界年龄因地而异,说明黄土地层的发育具有明显的地区差异。
TL ages of 56 samples of loess collected from Xingjiang and the middle reaches of the Huanghe River were determined by using fine-grained quartz and man-made light source bleaching techniques. The results indicate that:1. The well-preserved loess section in the Xingjiang region began depositing 400000 yr. ago. The loess/paleosoil series may be comparable with that observed in the middle-reaches of the Huanghe River but the depositing time was probably delayed 3000-50000 yr.2. The bottom boundary age of the Malan loess varies from one place to another. The TL dates can be divided into two groups: 70000-130000 yr. and 30000-50000 yr. The TL data are consistent with the appearance of two warmer climatic stages since the Pleistocene, indicating obvious regional differences in the stratigraphic development of loess, i.e., paleosoil occurred at the warm stage in the same place, but loess was deposited in other places. The initial age of loess deposition tends to become older from west to east and from south to north. In contrast, the cold climatic belt shows an opposite trend. The TL ages of loess provide strong evidence for the Quaternary stratigraphy throughout geological time and the shift tendency of climatic belt.3. The depositing rate of Malan loess along the middle reaches of the Huanghe River varies from place to place but its TL age shows a linear relationship with its depositing thickness. The depositing rate of loess in the north is higher than that in the south, suggesting that loess materials are derived from desert areas in northern China.
出处
《地球化学》
CAS
CSCD
北大核心
1989年第4期352-360,共9页
Geochimica
基金
中国科学院自然科学基金
