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Geo-Marine Letters

, Volume 25, Issue 4, pp 205–213 | Cite as

Geomorphology of unique reefs on the western Canadian shelf: sponge reefs mapped by multibeam bathymetry

  • Kim W. Conway
  • J. Vaughn Barrie
  • Manfred Krautter
Original

Abstract

Multibeam imagery of siliceous sponge reefs (Hexactinellida, Hexactinosida) reveals the setting, form, and organization of five reef complexes on the western Canadian continental shelf. The reefs are built by framework skeleton sponges which trap clay-rich sediments resulting in a distinctive pattern of low intensity backscatter from the reefs that colonize more reflective glacial sediments of higher backscatter intensity. Bathymetry and backscatter maps show the distribution and form of reefs in two large complexes in the Queen Charlotte Basin (QCB) covering hundreds of km2, and three smaller reef complexes in the Georgia Basin (GB). Ridges up to 7 km long and 21 m in height, together with diversely shaped, coalescing bioherms and biostromes form the principal reef shape in the QCB whereas chains of wave-form, streamlined mounds up to 14 m in height have developed in the GB. Reef initiation is dependent on the distribution of high backscatter-intensity relict glacial surfaces, and the variation in reef complex morphology is probably the result of tidally driven, near seabed currents.

Keywords

Sponge Biostrome Reef Area Reef Complex Reef Site 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

Notes

Acknowledgements

Rob Hare and Ernest Sargent of the Canadian Hydrographic Service are thanked for multibeam data collection, and the officers and crew of the CCGS Vector are recognized for their professionalism in the completion of this task. Norman Dale, University of Northern British Columbia (UNBC) is thanked for support and interest. Dixie Sullivan of Environment Canada and Keith Shepard of ROPOS made possible the successful McCall Bank ROV survey. Thanks to Kashka Iwanowska for multibeam data collection and compilation. Ralph G. Currie and an anonymous reviewer provided valuable reviews. The German Research Foundation (DFG KR 1902/2-2) and the University of Northern British Columbia are gratefully acknowledged for their financial support of this study.

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Copyright information

© Springer-Verlag 2005

Authors and Affiliations

  • Kim W. Conway
    • 1
  • J. Vaughn Barrie
    • 1
  • Manfred Krautter
    • 2
    • 3
  1. 1.Geological Survey of Canada, PacificSidneyCanada
  2. 2.Institut fuer Geologie und PalaeontologieUniversitaet HannoverHannoverGermany
  3. 3.GeoBio-Center at Ludwig-Maximilians-UniversitaetMuenchenGermany

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