Narrow-Beam Parasound Echosounder Recordings

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. 

The first example was recorded on the Rio Grande Rise in the western South Atlantic during RV Meteor cruise M29/2 (Bleil et al. 1994) and is typical for a calcareous environment (Fig. 2.25a). It is characterized by a strong sea bottom reflector caused by coarse-grained foraminiferal sands. Signal penetration is low and reaches only about 20 m 

The third example recorded in the Weddell Sea/ Antarctic Ocean during RV Polarstem cmise ANT Xl/4 as well (Kuhn, pers. communication) indicates a deep sea environment with clay sediments (Fig. 2.25c). Signal penetration again is high (about 140 m), and reflection horizons are very 

The fourth example from the distal Bengal Fan (Hiibscher et al. 1997) was recorded during RV Sonne craise S0125 and displays terrigenous features and sediments (Fig. 2.25d). Active and older abandoned channel levee systems are characterized by a diffuse reflection pattern which indicates sediments of coarse-grained turbidites. Signal penetration in such environments is rather low and reaches about 30 - 40 m. 

The density (p ) and bulk modulus (K ) of the sediment grains are the most important physical properties which characterize the sediment type -terrigenous, calcareous and siliceous - and composition. Additionally, they are required as input parameters for wave propagation modeling. 

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