Seabed sediment classification in the northern South China Sea using inversion method

摘要

Sub-bottom profile data can be used not only for the interpretation of the seabed strata structure and formation, but also for seabed sediments classification using inversion method. In the present paper, sub-bottom profile data from a survey line located on the continental slope of the northern South China Sea were processed. The data collected were used to calculate seabed reflection coefficient and attenuation rolloff, while sediment acoustic characteristics parameters, including porosity and permeability, were defined based on the Biot model that calculates wave propagation in sediment-fluid mixtures. Finally, the mean grain sizes and corresponding sediment classification were quantitatively estimated. By comparing the inversion result with sediment description of gravity piston cores which were acquired near the survey line, we found that the results from inversion method accord with the particle size analysis of sediment cores. However, the inversion method is only suitable for the soft seabed sediments such as mud or sand. The petrous sediment in the survey is classified by Gardner formula and we concluded the petrous seabed sediments are carbonate crusts which are generated from leaky gas hydrate.