Sediment echosounding

5-lO dB m in coarse-grained sediments (Fig. 2.20b). Accordingly, shear moduli are also low and do not vary very much (Fig. 2.21b) so that higher P-wave velocities in terrigenous sediments mainly result from higher bulk moduli (Fig. 2.21a). 

Calcareous foraminiferal and nannofossil oozes (NFO) show similar trends in both P-wave and S-wave parameters as terrigenous sediments, but are shifted to higher porosities due to their additional intraporosities (GeoB2821-l Figs. 2.19, 2.20). 

Permeabilities estimated from the least square inversion mainly reflect the attenuation charac- 

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While studies on sediment cores only provide iirformation on the local core position, lateral variations in physical properties can be imaged by remote sensing methods like high-resolution seismic or sediment echosounder profiling. They facilitate core-to-core correlations over large distances and allow to evaluate physical property logs within the local sedimentation environment. 

Fig. 2.12 Frequency-dependent attenuation and phase velocity curves and power (n) of the attenuation law a = k f" computed for P-and S-waves in typical sand, silt and clay. The gray-shaded areas indicate frequency hands typical for ultrasonic measurements on sediment cores (50 - 500 kHz) and sediment echosounder surveys (0.5 - 10 kHz). Modified after Breitzke (1997).

Which parameter determines the amplitude or strength of reflection horizons during sediment echosounding, and which are the two physical properties that contribute to it ... 

Finally, some examples from high-resolution narrow-beam echosounder recordings present remote sensing images of terrigenous and biogenic sedimentation enviromnents (Sect. 2.6). 

Finally, some examples of Parasound echosounder recordings from different terrigenous and biogenic provinces are presented to illustrate that characteristic sediment compositions can already be recognized from such remote sensing surveys prior to the sediment core retrieval. 

Bergmann U., 1996. Interpretation of digital Parasound echosounder records of the eastern Arctic Ocean on the basis of sediment physical properties. Rep. on Polar Research, Alfred-Wegener Institute for Polar and Marine Research, Bremerhaven 183 164 pp... 

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