Scotian Slope Mapping Project: The benefits of an integrated regional high-resolution multibeam survey

Abstract

Abstract A regional multibeam bathymetric and imagery survey of the Canadian Scotian Margin was performed by C & C Technologies, Inc. The survey was spearheaded by the Geological Survey of Canada (Atlantic), which acted as a partner with an industry group consisting of Marathon Canada, Norsk Hydro Canada, PanCanadian, and Murphy Oil. The survey is providing one component for use in hazard assessment within the lease block area of the central Scotian Slope, and forming an integral part of regional research carried out by the Geological Survey of Canada Atlantic (GSCA) funded by PERD and industry partners. The multibeam imagery is being used to derive a regional assessment of the character of seabed morphology, erosion, and the distribution of slope instabilities throughout the Scotian Slope. Spatial resolution is higher than in 3-D seismic data, especially on the mid to upper Slope, and the 17,000 km2 survey area provides regional coverage. Many of the large features (canyons and slope instabilities) on the Scotian Slope extend for many kilometers, and therefore their interpretation requires regional information. In particular, the multibeam imagery allows precise targeting of seabed features for subsequent higher resolution surveys of small critical areas and seabed sampling. Side scan sonar, sub-bottom profiling, and ROV surveys can provide fine detail of critical features. Precisely located samples can be used to obtain measurements of sediment properties, age dating of sediments, and benthic biota. A 30-day sampling cruise was performed by GSCA on the CCGS "Hudson", which acquired high-resolution seismic profiles and piston and box cores in targeted features. The targeted data will be used to ground truth the multibeam imagery and to assess geologic conditions and hazards of the Scotian Slope. The bathymetry data are being evaluated with new technology developed by the University of New Brunswick, Canada, which interactively integrates them into one common graphical environment and allows for precise identification of geologic correlations. Introduction Many exploration and production companies are showing interest in the Scotian Slope off eastern Canada. More than 3,000,000 ha. have been leased since 1999 (Fig. 1). In spring of 2000, C&C Technologies acquired more than 16,500 km2 of multibeam bathymetry (Fig. 2) and backscatter data from the central part of the Scotian Slope using an EM300 system. The survey covered 15 lease blocks and extended from about 700 m to 3000 m water depth. In addition, a separate survey by Clearwater Fine Foods Inc. and the Geological Survey of Canada acquired multibeam bathymetry from 700 m to 150 m water depth on the upper slope using an EM1002 system. The purpose of the survey was to provide the GSC(A) and industry partners with regional information on surficial hazards, including sediment slides, surface faulting, and pockmarks, and on the distribution of near surface sediments that influence benthic habitat. Following the acquisition of the multibeam data, the Geological Survey of Canada, with supplementary funding from the industry partners, carried out two 15-day confirmation cruises.