INVERSION OF SEDIMENT GRIAN SIZE COMPOSITION WITH X-RAY COMPUTED TOMOGRAPHY METHOD——AN EXAMPLE OF MODERN SEDIMENTATION IN THE SUBAQUEOUS HUANGHE(YELLOW)RIVER DELTA
X-ray computed tomography(CT)allows for high-resolution and nondestructive analysis of sediment cores,and for exploring the relationship between CT data(i.e.,the CT value)and sediment grain size to achieve rapid,continuous acquisition of sediment properties from cores,and to enhance comprehensive understanding of core depositional processes.Based on multiple cores taken from the subaqueous Huanghe(Yellow)River Delta,CT scanning was performed to obtain the CT values,and high-resolution grain size was analyzed to quantify the relationship between CT value and grain size compositions.Results suggest that the sediments in the subaqueous delta are mainly silt,and the CT value is mainly distributed between 700 and 1 000 HU.A significant nonlinear positive correlation between mean grain size and CT value was found,and the relationship equation between mean grain size and the CT value was constructed.In addition,a good correspondence between sand,silt,clay contents in the sediments and the CT intervals of 1 200～1 500 HU,800～1 200 HU,600～800 HU was revealed,from which the grain size fractions could be estimated.The application verified that the inversion of grain size compositions and mean grain size of sediment cores with CT scanning CT value was effective.Therefore,this method could be used for the inversion of grain size composition of sediments in other marine areas.
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