Work Package: Seismic Reflection and Refraction Survey (SR)

The seismic work was part of Canada’s UNCLOS (United Nations Convention on the Law of the Sea) program to map the extended continental shelf in the Arctic Ocean. The seismic work was divided into two phases, with the two ships operating together during the first phase and separately during the second. The first phase ran from August 11 until September 2, 2016 and was carried out with an airgun array on CCGS Louis S. St-Laurent for a seismic source while Oden deployed seismic receivers (18 sonobuoys and 6 Taurus ice stations). Additional receivers were deployed from CCGS Louis S. St-Laurent and both vessels recorded the data transmitted from all active sonobuoys. Coincident seismic reflection data were obtained by towing a streamer behind CCGS Louis S. St-Laurent while Oden sailed ahead to break ice. Five seismic lines were acquired: two crossing the Lomonosov Ridge, one along the Marvin Spur, and two from the Makarov Basin and onto the Alpha Ridge.

During the second phase of the program, Oden acquired seismic data on her own in Amundsen Basin. Prior to data acquisition, Oden first broke a track through the ice and then returned along the track to collect seismic data. Reflection data were recorded on a 200-m-long streamer towed behind the Oden, while wide-angle seismic reflection/refraction data were recorded by 14 sonobuoys and two Taurus ice stations. A total of 197 km of seismic reflection data were acquired along four seismic lines. The seismic reflection records are of high quality and provide information on the sedimentary structure down to the basement. The sonobuoys recorded refractions from both the sedimentary layers and the crust up to offsets of >20 km.

Seismic lines acquired during the first phase were primarily designed to answer questions on the large-scale tectonic development and opening history of the Arctic Ocean and to better describe the crustal structure of the ridges and spurs found in the basins. In terms of UNCLOS, this information will improve the general understanding of the geological setting of the extended continental shelf along Canada’s Arctic margin and will help to classify the submarine ridges and elevations. During the second phase of the expedition, seismic data were collected to determine the sediment thickness in Amundsen Basin to document Gardiner points for the delineation of the outer limits of the continental shelf.