The grain-size characteristics and their environmental indications of the island intertidal surface sediments of Zhanjiang offshore area
湛江海区海岛潮间带表层沉积物特征及对沉积环境的指示

In order to elucidate the hydrodynamic force from grain-size data of intertidal zone sediment and the corresponding relationship between sediment grain-size and hydrodynamic transport modes,136 sediment grain-size samples that collected from 29 islands of Zhanjiang offshore area were analyzed.Several research tools,including C-M graph,grain-size cumulative curves and factor analysis,were introduced to analyze the grain-size data.The clustering analysis indicates that the content of fine fractions is stable;in comparison,that of coarse fractions is unstable.The fine fractions are deposited on the condition of weak hydrodynamics and the coarse correspondences are generated by sea-water disturbance.Two transport ways,suspension and saltation,are recognized through C-M graph and grain-size cumulative curves.The same conclusions are obtained from three analysis of C-M graph,grain-size cumulative curves and factor analysis.Three principal transport modes,suspension,displacive precipitation and saltation,affect intertidal sediment deposit,are corresponding to,respectively,the grain-size range of 5φ to larger than 11φ,of –1φ to 1φ and of 2φ to 4φ.Therefore,intertidal sediment grain size can be applied soundly to discuss the hydrodynamic environment.