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- 责任者：Cai Xiangmin (Geological Survey Institute of Beijing ; Beijing 102206 ; China) ; Guo Gaoxuan
- 刊名：Quaternary Sciences
- 出版年：2010
- 卷期：30(1)
- 关键词：河流 ; rivers ; 北京 ; Beijing
- 页码：p.167-174
- 图表：illus., 113 refs.
- 分类号：1400
- issnNo：ISSN1001-7410
- isbnNo：CN11-2708/P
Lots of borehole data show that the sedimentary environment was obviously different before and after the formation of the Yongdinghe River. Before its formation，the lake facies dominated this region. After its formation，the alluvial and pluvial facies dominated this region. This paper provided a detailed magnetostratigraphic record based on 273 samples from New Borehole 5 in the Beijing plain area. Stepwise alternating field (AF) demagnetization is used to isolate the magnetic component in these samples. The pattern of magnetic polarity sequence given by the record is well matched with the geomagnetic polarity timescale. The gompholite at the bottom of the borehole should be the oldest sediment by the Yongdinghe River，so it should be formed about 3.0 Ma B.P.，that is，in the Pliocene Epoch.