图解法和矩值法海洋沉积物粒度参数的对比

Comparative Study on Grain-size Parameters of Marine Sediment Derived from Graphic and Moment Methods

【目的】系统探讨图解法和矩值法计算海洋沉积物粒度参数结果的相互转换关系。【方法】首先对雷州半岛南三岛海滩沉积物开展图解法和矩值法粒度参数的对比研究,然后将结果与其他分析结果相结合,讨论两种方法在不同沉积环境中的转换规律。【结果】对于南三岛海滩样品而言,两类方法获得的平均粒径和分选系数相关性较高(R^2≥0.821),可相互转换,但偏态和峰态的相关性较弱(R^2≤0.229),不存在相互换算的数学基础;对于不同沉积环境的样品而言,两类方法的计算结果不存在随计算公式阶次增加而相关性逐渐变差的普适规律;两类方法所得的平均粒径和分选系数可相互换算,但偏态和峰态在不同沉积环境中的可换算性差异较大。【结论】图解法和矩值法计算的粒度参数在不同沉积环境存在较大差异,不能直接相互替代。

【Objective】The interconversion relationship between the grain-size parameters of marine sediment calculated by graphic measures(GM)and moment measures(MM)is investigated in this study.【Method】First,a comparative study on grain-size parameters of beach sediment of Nansan Island,Leizhou Peninsula,has been carried out.Then,the comparative results of various sedimentary environments are collected to systematically analyzed the transformation relationship between the results of GM and MM.【Result】The results show that:in terms of the beach sediment,the mean grain size and sorting coefficient calculated by GM and MM both have a high correlation(R^2≥0.821),which means that they can be converted to each other;but the correlation of the skewness and kurtosis are very poor(R^2≤0.229),which means they cannot be converted to each other;for sediment samples of different sedimentary environments obtained by statistical methods,no general rule of the relationship of particle size parameters between GM and MM is found with the increase of moment;the mean grain size and sorting coefficient of GM and MM can be converted to each other,but there is a great difference in the convertibility of the skewness and kurtosis calculated by GM and MM in different sedimentary environments.【Conclusion】It is suggested that the conversion relationship of the grain-size parameters between moment measures and the folk&Ward graphical method need to be clarified,before using MM to describe the physical meaning of the particle size parameters of sediments.