The correlation between of magnetic fabric and the grain size parameters characteristics of dam-broken sediments

摘要

In order to establish recent dam-broken sediment identification markers in the middle reaches of Yangtze River, we studied the magnetic fabric and grain size characters of the dam-broken fan sediments of Paizhouwan, Which was formed in 1998. The result demonstrates that, ①The main grade of the dam-broken fan sediments is composed of sand (up to 97.7%), and most of which is fine sand (up to 50.281%) with little clay. ② From the root to edge of the dam-broken fan, the sand composition accounts for decreases, while the content of fine sands and clay composition increases, the grain size changes from coarse to fine, and the skewness coefficient Sk changes from small to large. ③The dam-broken fan sediments is moderately sorted and the sorting grade in the edge is poorer than that of the root. The skewness coefficient of most samples are less than -0.11, which belongs to negative skewness. Each coefficient of kurtosis Kg is all the larger than 1.11, which reflecting the probability curves of the dam-broken fan are a little bit narrow. ④ The magnetic fabric parameters k, P, F, L and Fs changes from large to small from the dam-broken fan root to edge. ⑤The magnetic fabric parameters Fs, p have a positive correlation with the grain size parameters Kg and Mz, and have a negative correlation with the Sk., St.