Sediment types determination using acoustic techniques in the Northeastern Gulf of Mexico

Normal incident acoustic techniques were used todetermine values of sediment properties (acoustic impedance,sound speed, bulk density, porosity, shear strength, water content,and mean grain size) and map those (acoustic impedance andgrain size) in the northeastern Gulf of Mexico. The acoustic datawere acquired using a 11 kHz normal incident echo sounder overstrength was determined by the comparison of acoustic data tomeasured impedance from five core samples (ground truth data).This echo strength calibration was used for the entire data set. Val-ues of sediment properties were calculated from sediment imped-ance using the regressions compiled from the historical coredatabase. Comparison of ground truth and echo strength to datafrom 20 additional core locations shows close agreement. Discrep-ancies are probably due to navigation errors or weak returns indeeper water. In addition, sediment disturbance and frequency dis-persion can be considered. Using acoustic derived sediment prop-following types: sandy/silty clay (impedance, 1.6-2.0 106 kg/m2 s),sand-silt-clay and/or clayey sand (impedance, 2.01-2.40 106 kg/m2s), silt or fine sand (impedance, 2.41-2.90 106 kg/m2coarse sand (impedance, 2.91-4.0 106 kg/m2 s). The areal distri-butions of the four types coincide with the previous reports basedon sediment sampling. Therefore, the acoustic technique can effec-tively be used to define and classify sediments and map sedimentprovinces. KCI Citation Count: 2