A Study Of Fractal Characteristic Features Of Typical Sediments From The South China Sea

Fractal is a common phenomenon in nature,and some kinds of detrital materials also show fractal features.Whether the grain-size of marine sediments has fractal characteristics,and the fractal dimension of grain size in sediments from different marine environments,as well as its control factors,remain unclear.In the present study,the grain-sizes of sediments from five sedimentary cores collected from typical sedimentary areas in the South China Sea were analyzed.The studied cores were named C1,C2,C4,QD2 and NHX3,and the water depths of the cores gradually increased.Grain-size compositions of 189 subsamples in the above five sediment cores were analyzed.It was found that with the increase in water depth and offshore distance,the grain-size compositions of the sediments changed.The silt content increased,but the sand level decreased significantly.In comparison,it is discovered that grain-size parameters of the cores displayed obvious spatial characteristics.For example,with the increase of offshore distance and water depth,both the mean grain-size and standard deviation decrease,and the sorting of the sediments gradually becomes better.The kurtosis of the sediment samples shows gradual increasing.In contrast,the variation of the skewness was not evident.Both the C-M diagram and the probability cumulative curve of the sediments suggest that the transportation forms of the particles change gradually from rolling at inshore area to suspension at deep water.Grain-size of the five sampling sites shows evident fractal characteristics,and with the increase of the distance from the land and water depth,the fractal dimension displays a gradual decreasing trend.Similarly,the mean fractal dimensions decreases from 2.52 at C1 to 2.10 at NHX3.In comparison with sediments in some other Chinese oceans,a relatively higher level of fractal dimension for grain-size in the five cores,especially C1,were found.Through statistical analysis,it is unveiled that fractal dimension of the grain-size and standard deviation were positively and significantly correlated,suggesting that the degree of sorting of the particles affects the fractal dimension of the grain-size.It is thus hypothesized that sorting acts as the main controlling factor of the fractal dimension of grain-size in the South China Sea.At the same time,this study established an endmember analysis model for grain size,The good agreement between simulation data and the measured data indicates that the model has a potential application to be used in future grain size study.In addition,we carried out the sensitive grain-size of five columns.It was found that the strength of hydrodynamic conditions is negatively correlated with the sensitivity of the finer-grained sensitive fractions to the environment,which can be used as a reference for subsequent environmental analysis.