汉江上游黄坪村段古洪水滞流沉积物研究及意义

The Significance of Palaeoflood Slack Water Deposit in Huang Ping Site in Hanjiang River

古洪水滞流沉积物是古洪水事件的直接产物,蕴含古洪水的重要信息。以汉江上游郧县黄坪村剖面为研究对象,对其粒度、磁化率、烧失量及碳酸钙等进行了分析。结果表明:古洪水滞流沉积物的粒度具有粉砂含量】砂级颗粒】黏粒含量的特征;磁化率值在78×10-8~81.2×10-8m3kg-1之间;烧失量值较低为23.9~27.7 g kg-1,碳酸钙为2.72%~3.20%。其宏观特征和上述参数与黄土和古土壤有明显的区别。沉积物的粒度组成特征及粒度参数、磁化率、烧失量、碳酸钙等对于鉴别古洪水滞流沉积层有重要的参考价值。

The palaeoflood SWD is the important vector to rebuild the palaeoflood event. This paper studied the palaeoflood slack water deposits in the Huang ping profile, located in the Huang ping site, in the first level river terraces of the upper Hanjiang valley. The grain size distribution, magnetic susceptibility, loss-on-ignition and CaCO3 were measured in the laboratory. The results showed that the grain size feature of the palaeoflood SWD sequenced by silt > sand > clay, the magnetic susceptibility values were between 78×10-8~ 81.2×10-8m3kg-1, the loss-on-ignition values were between 23.9 ~ 27.7 g kg-1, and the CaCO3 values were between 2.72% ~3.20%. The different characteristics were discussed between the palaeoflood slack water deposits and other sedimentary, such as the palaeosoil and Malan loess. In addition, the based discrimination was pointed out for the palaeoflood slack water deposits in the upper of Hanjiang River valley by the field macroscopic characteristics and the physical and chemical indicators.