USE OF A CONVENTIONAL ECHO-SOUNDER AND TEXTURAL ANALYSES IN DELINEATING SEDIMENTARY FACIES: SCOTIAN SHELF

Abstract

The topographical features of the Scotian Shelf within the study area consist of two elongated basins and three isolated banks. The configuration conforms in a general manner to that of other formerly glaciated shelves.A variety of sediments occurs in the area and has been mapped in terms of an echogram classification. The classification is based on the shape of the surface of the bottom, as well as the relative degree of compaction of the sediment. An echo-sounder with a short pulse length and relatively high frequency was found particularly suited for this purpose.The data from textural analyses on 141 samples correlate well with the echo-gram results. Together, these techniques constitute an effective approach to the problem of obtaining a detailed picture of the surficial bottom geology, and in addition, stratigraphic relations are sometimes revealed. The sedimentary units or facies are interpreted in terms of depositional environments.The study suggests that the area was covered with glacial drift during the Pleistocene epoch and that subsequently, during a low stand of sea level indicated by a submarine terrace at 110–115 m, the glacial debris was reworked around the topographic highs and much of the finer sediment was transported and deposited in the adjacent basins.