【作者】 殷伟德； 钱方； 徐树金；

【Author】 Yin Weide Qian Fang Xu Shujin (Institute of Geomechanics,Chinese Academy of Geological Sciences)

【机构】 中国地质科学院地质力学研究所；

【摘要】 <正>本文系1980年,笔者随地质矿产部青藏高原地调大队八分队对四川巴塘竹笆笼金沙江边,西藏芒康竹卡澜沧江边,八宿怒江东岸队及波密县波都藏布江河谷中的松宗,卡达桥和索通乡等地的第四纪河湖相地层,阶地堆积物进行磁性地层研究成果(图1)。更多还原

【Abstract】 Multistage terraces are developed along the wider parts of the valleys of rivers Jinshajiang,Lancangjiang,Nujiang and Boduzangbu in eastern Xizang (Tibet),but their deposits are generally made of coarse grains in small thi- ckness,and are often very narrow with frequent depositional interruptions. These characteristics brought about certain difficulties for the palaeomagnetic work.In 1980,we collected 86 palaeomagnetic specimens of six Quaternary sections from fluviolacustrine deposits and loesses that are distributed in the terraces and valley floors at the eastern side of Jinshajiang near Zhubalong in Batang,Sichuan,at both sides of Lancangjiang near Zhuka in Markam,at the eastern side of Nujiang in Baxoi,at Sumzom,Kadaqiao and Suotongxiang in Bomi,Xizaing(Tibet). In the palaeomagnetic laboratory processes,demagnetizing treatment was made for different lithologic specimens,and the demagnetizing curves were drawn.Then we selected the alternating magnetic field of which peak value was 25mT to make demagnetizing treatment for all specimens.After that, three vectors of the magnetic field for every specimen were measured with unoriented magnetic field-balance,and their magnetic declinations,inclinations and intensities of remanent magnetism ware calculated.Finally,magneto-stra- tigraphic columnar section of the six sections was drawn. The polarities of all the specimens of the six sections are normal.Acco- rding to geomorphic positions,depositional characters,types of fossil soils and sporo-pollen assemblages of the six sections,we consider that they were de- posited during Brunhes Epoch,and their time does not exceed 730,000 years.更多还原