|Title||Seabed conditions on the inner shelves of Atlantic Canada|
|Licence||Please note the adoption of the Open Government Licence - Canada
supersedes any previous licences.|
|Author||Eamer, J B R; Shaw, J; King, E L; MacKillop, K|
|Source||Geological Survey of Canada, Open File 8731, 2020, 161 pages, https://doi.org/10.4095/326514 (Open Access)|
|Links||Bathymetric Data - Données bathymétriques|
|Publisher||Natural Resources Canada|
|Related||NRCan photo(s) in this
|Province||Eastern offshore region; New Brunswick; Newfoundland and Labrador; Nova Scotia; Prince Edward Island|
|NTS||1; 2; 3D; 10; 11; 12B; 12G; 12H; 12I; 12J; 12O; 12P; 20; 21; 22A|
|Area||Gulf of St. Lawrence; Cape Breton Island; Bras d'Or Lakes; Burin Peninsula; Avalon Peninsula; Straight Shore; Notre Dame Bay; Great Northern Peninsula; St. George's Bay; Sable Island; Baie des Chaleurs;
Northumberland Strait; Magdalen Islands; Bay of Fundy|
|Lat/Long WENS|| -68.0000 -52.0000 52.2500 42.0000|
|Subjects||marine geology; regional geology; surficial geology/geomorphology; engineering geology; geophysics; Nature and Environment; Science and Technology; Health and Safety; continental margins; continental
shelf; fiords; seafloor topography; bedrock topography; bedrock geology; lithology; structural features; postglacial deposits; marine sediments; deltas; submarine fans; glacial deposits; ice contact deposits; tills; moraines; drumlins; muds; sands;
gravels; boulders; overburden thickness; bathymetry; scouring; bedforms; sea ice; icebergs; submarine features; gas; salt diapirs; mining activities; collapse structures; subsidence; sinkholes; geological history; glacial history; depositional
history; sea level changes; sediment reworking; sediment dispersal; salt tectonics; deformation; geophysical surveys; New Brunswick Continental Shelf; Magdalen Shelf; Cape Breton Shelf; Atlantic Continental Shelf; Scotian Shelf; Cape Ray Shelf;
Prince Edward Island Platform; Cape Breton Trough; marine spatial planning; infrastructures; development; cumulative effects; geological hazards; diamicton; glaciomarine sediments; bedform migration; submarine valleys; classification; clast
lithology; Phanerozoic; Cenozoic; Quaternary; Tertiary; Mesozoic; Cretaceous; Triassic; Paleozoic; Permian; Carboniferous; Devonian; Silurian; Ordovician; Cambrian; Precambrian; Proterozoic|
|Illustrations||location maps; geoscientific sketch maps; tables; photographs; geophysical profiles; profiles; cross-sections; correlation sections; 3-D images; 3-D models|
|Program||Marine Geoscience for Marine Spatial Planning, Cumulative effects, marine component|
|Released||2020 08 14|
The shallow seafloor of Atlantic Canada (<100 m) displays a great diversity of conditions, necessitating a subdivision into 23 unique regions.
For each region we summarize the
combinations of bedrock type, seafloor morphology, and surficial sediments as they are relevant to the emplacement of offshore infrastructure (e.g. piles, anchors, cables, pipelines).
The surficial sediment (overburden) found throughout the 23
regions comprises combinations of glacial diamict (ice-contact sediment or till), glaciomarine mud, postglacial mud, and postglacial sand and gravel, each unit having differing geotechnical properties.
Because of resistance and boulder content,
till presents the greatest challenge to the emplacement of monopiles. The distribution and thickness of the remaining surficial units varies across the regions. Relatively thick deposits of postglacial mud and glaciomarine mud are found in parts of
regions 1, 5, 8, and 11.
The most extensive area of shallow water, low relief, and very thin overburden (e.g., suitable for gravity-based development) is the southern Gulf of St. Lawrence and off northeast Cape Breton (regions 2, 3, 4 and 6).
Smaller areas of similar character exist off the Newfoundland coast (regions 16, 18, and 21).
Widespread thick (>25 m) overburden suitable for pile installation is only present in one large area: Region 12, Sable Island - on the outer continental
Factors that may present difficulties to development include: a) Seafloor scour and bedform migration (regions 2 - 6, 11, 12, 16, 18, and 21); b) pervasive sea ice and icebergs (regions 16 - 20); c) incised submarine valleys (regions 1, 2,
3, 5, 7, 23); d) extensive gas in sediments (regions 1, 9, 12, 21, 22); e) salt diapirs (regions 4, 6, 22); and f) seafloor collapse due to mining (region 7). See Introduction Figure 7 for map of regions.
|Summary||(Plain Language Summary, not published)|
With increasing global development of the seabed for emerging renewable energy technologies (wind, wave and tidal), it is timely to re-examine the inner
continental shelf of Atlantic Canada. The results of these analyses are presented here, where we describe the seabed foundation conditions including seabed geology, geohazards and geotechnical properties as a guide for any future seabed installations
and related infrastructure.