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Alternating bottom-current-dominated and gravity-flow-dominated deposition in a lower slope and rise setting—insights from the seismic geomorphology of the Western Scotian Margin, Eastern Canada
Campbell, D.C.; Deptuck, M.E. (2012). Alternating bottom-current-dominated and gravity-flow-dominated deposition in a lower slope and rise setting—insights from the seismic geomorphology of the Western Scotian Margin, Eastern Canada, in: Prather, B.E. et al. (Ed.) Application of the principles of seismic geomorphology to continental-slope and base-of-slope systems: case studies from seafloor and near-seafloor analogues. pp. 329-346. hdl.handle.net/10.2110/pec.12.99.0329
In: Prather, B.E. et al. (Ed.) (2012). Application of the principles of seismic geomorphology to continental-slope and base-of-slope systems: case studies from seafloor and near-seafloor analogues . SEPM: Oklahoma. ISBN 978-1-56576-304-3. hdl.handle.net/10.2110/pec.12.99, more

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Keyword
    Marine
Author keywords
    sediment wave sediment drift unconformity mixed turbidite–contourite system Scotian margin mass-transport deposit

Authors  Top 
  • Campbell, D.C.
  • Deptuck, M.E.

Abstract
    The seismic geomorphology of a succession of alternating gravity-flow-dominated and bottom-current-dominated deposits along the continental slope and rise off western Nova Scotia demonstrates the importance of inherited geomorphology on subsequent deposition patterns in mixed turbidite and contourite depositional systems. In the study area, widespread mass wasting and channel incision during the Miocene created a steep ramp with a complex geomorphology along the lower continental slope. In the Late Miocene and Pliocene, a sediment drift was constructed on the continental rise, forming a 50-km-wide terrace that onlapped the steeper slope. The location, style, and evolution of sediment waves associated with this sediment drift appear strongly linked to the morphology of the underlying surface. The orientation and extent of wave crests show strong correspondence to underlying geomorphic elements, with the most prominent sediment waves forming downcurrent of seafloor perturbations like failure escarpments and salt diapirs. The erosional and constructional morphology of the contour-current-swept seafloor in turn strongly influenced the trajectory and response of subsequent down-slope-oriented submarine sediment gravity flows later in the Pliocene. Preferential accumulation took place above a regional terrace constructed as the sediment drift evolved, promoting deposition from sediment gravity flows that may have otherwise been transported into deeper water. The positive relief of wave crests guided sediment gravity flows down the slope, with erosion and deposition focused along wave troughs. This study highlights the complex feedback that exists between along-slope and down-slope constructional and degradational processes.

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