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为了探讨“巫山黄土”的成因类型,对新近发现的“巫山黄土”进行了磁组构测试和磁化率主轴特征分析,并与长江现代沉积物以及长江中游一带分布的风积黄土和“砂山”的磁组构特征进行了对比.结果表明:(1)“巫山黄土”的κ、P、F、L、E值与风积黄土和“砂山”接近,却明显低于长江现代沉积物的相应值;(2)在磁组构参数F-L关系图上,“巫山黄土”的数据点多集中于坐标原点附近,与长江中游一带风积黄土和“砂山”的特征也类似,均指示了沉积动力相对比较弱的沉积环境.而长江现代河流沉积物的数据点却主要分布于F轴附近,反映长江现代河流沉积物的F较L发育;(3)“巫山黄土”的磁化率最大主轴特点也与长江中游风积黄土和“砂山”的接近,偏角的方向比较分散,长轴的倾角为36°～38°,短轴的倾角为37°～39°,而长江现代河流沉积物的磁化率最大主轴偏角的方向比较稳定,并且长轴的倾角一般小于10°,短轴的倾角大于80°;(4)“巫山黄土”样品的T值介于-1～1之间,而长江现代河流沉积物的T值却主要以大于1为主.综合看来,“巫山黄土”的磁组构特征与长江中游一带的风积黄土和“砂山”接近,指示了其风积成因的特点.
In order to explore the genetic type of “Wushan loess”, the magnetic structure test and the analysis of magnetic susceptibility of the newly discovered “Wushan loess” were carried out and analyzed with the characteristics of the main sediments of the Yangtze River and the aeolian loess distributed in the middle reaches of the Yangtze River The results show that: (1) The values of κ, P, F, L and E in Wushan loess are close to that of the aeolian loess and sandy mountain, But obviously lower than the corresponding values of the modern sediments in the Yangtze River. (2) On the FL diagram of magnetic structure parameters, the data points of “Wushan loess” are mostly concentrated near the origin of coordinates, The characteristics of “Sand Mountain” are also similar, indicating the sedimentary environment with relatively weak depositional dynamics, while the data points of the sediments of the modern Yangtze River are mainly distributed near the F axis, reflecting the development of F over L sediments in modern rivers of the Yangtze River. (3) The maximum magnetic susceptibility of “Wushan loess” is also close to the “loess sand” in the middle reaches of the Yangtze River and the direction of declination angle is relatively dispersed. The major axis inclination is 36 ° ~ 38 ° The inclination angle of the shaft is 37 ° ~ 39 °, while the direction of the maximum magnetic susceptibility of the sediments in the Yangtze River is relatively stable. And the dip of the major axis is generally less than 10 ° and the dip angle of the minor axis is greater than 80 °. (4) The T value of Wushan loess sample ranges from -1 to 1, while the T value of modern river sediments in the Yangtze River Mainly based on more than 1. According to the comprehensive view, the magnetic fabric of “Wushan loess” is close to the “volcanic loess” and “sand mountain” in the middle reaches of the Yangtze River, indicating its aeolian genesis.