3D bathymetry and acoustic seabed classification of pelotas basin, Brazil

Abstract

An acoustic seabed classification of the Pelotas Basin (PB) was generated and overlaid on a 3D bathymetric representation, which was elaborated from acoustic and altimetry data. The map was validated with sedimentological charts in order to identify areas of morpho-sedimentary interest. The hydroacoustic data used were acquired with a SIMRAD EK500 scientific echo sounder operating at a frequency of 38 kHz, obtained over twenty cruises totalling 5,249,191 acoustic readings during 15,367 nautical miles in the PB. Bottom features such as the Rio Grande Valley, Rio Grande Cone, Rio Grande Terrace and Florianopolis terrace were identified. BSBS (Bottom Surface Backscattering Strength), expressed in decibels (dB), is a logarithmic ratio between the incident acoustic energy and the energy reflected by the seabed. In general, the PB showed intermediate BSBS values. Lower BSBS values, which are associated with finer sediments were found on the continental slope and the oceanic areas. On the other hand, higher values associated with coarse sediments did not occupy large areas. Good correspondence was found between high BSBS values and areas with coarse bottom sediment according to the sedimentological charts. The integration of bathymetry and BSBS data together with available sedimentological information and maps of non-renewable resources of the BP enabled the identification of potential areas for mineral exploitation at the region.