Illuminating centimeter-level resolution stratum via developed high-frequency sub-bottom profiler mounted on Deep-Sea Warrior deep-submergence vehicle

Abstract

Sub-bottom profiling traditionally uses low-frequency signals (less than 20 kHz) to examine layered structures of the bottom sediment in large depth, but it has some limitations in deep-sea surveying. The surficial sediment within several meters under the water–sediment boundary in the deep sea cannot be distinguished clearly. In this study, a high-frequency sub-bottom profiler (HFSBP) was developed and applied to a manned deep-submergence vehicle (DSV), named Deep-Sea Warrior, to obtain a centimeter-level resolution stratum of several meters in the deep-sea surficial sediment. Twelve diving tests were carried out, the diversity of surficial benthic profiles on the northern slopes of the South China Sea was shown up for the first time and as many as four layers profiles were obtained in the low bending canyon region, rock surface profiles, discontinuous stratum structures and thick surficial sediment in the deeper region. Continuous and clear stratum structures within a range of about 2 m on the seabed surface sediment were obtained in 11 of the 12 dives. As the dive sites took a certain dispersive distribution, it reflected that the stratum structure of surficial sediment was prevalent in the northern slopes area of the South China Sea for the most part. To verify the effectiveness of HFSBP, a laboratory test in an anechoic tank was performed, and the experiment results verified the layered ability and the thickness measurement stability of it. The comparison was performed with shipboard data of deep-sea sub-bottom profiler (SBP) Bathy-2010, and the HFSBP results were obviously better than those of Bathy-2010 measurement. The clear and continuous fine layered data obtained by HFSBP may help scientists in new area research in marine geophysics.

Keywords:

• High-frequency sub-bottom profiler
• deep-sea sediment
• high-resolution stratum
• wide-band
• pulse compression

Disclosure statement

No potential conflict of interest was reported by the authors.