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TitleGeophysical evidence for bottom current activity throughout the Cenozoic from the continental margin off Nova Scotia, Canada
AuthorCampbell, D CORCID logo; Mosher, D CORCID logo
SourceGeological Association of Canada-Mineralogical Association of Canada, Joint Annual Meeting, Programs with Abstracts vol. 35, 2016 p. 20
Alt SeriesEarth Sciences Sector, Contribution Series 20130460
PublisherGeological Association of Canada
MeetingGeological Association of Canada (GAC) and the Mineralogical Association of Canada (MAC) Joint Annual Meeting; St. John's; CA; May 27-29, 2013
Mediapaper; on-line; digital
File formatpdf
ProvinceEastern offshore region
AreaScotian Margin
Subjectssedimentology; marine geology; stratigraphy; sediment transport; sedimentation; marine sediments; bottom sediments; sediment dispersal; submarine features; seismic data; erosion; bottom currents; Western Boundary Undercurrent (WBUC); Cenozoic
ProgramOffshore Geoscience
Released2016 01 01
AbstractThe widespread sediment drifts that flank the continental margins of the North Atlantic provide geological evidence for bottom current activity throughout the Cenozoic. Prior to this study, sediment drifts and other features indicative of active bottom currents were thought to be of limited extent along the continental margin off Nova Scotia (the Scotian margin), making the Scotian margin anomalous compared to the adjacent margins to the north and south. In this study, we demonstrate that sediment drifts are a common feature in the Cenozoic succession along the Scotian margin. Analysis of recently acquired 2D and 3D multichannel seismic reflection data combined with published biostratigraphic results suggest that large sediment drifts developed in the Late Miocene to Pliocene, and possibly as early as the Late Eocene. These large drifts represent more than 50% of the preserved Cenozoic succession along parts of the western Scotian margin and exceed 1.4 km in thickness. Small sediment drifts developed locally throughout the late Paleogene and Neogene, either southwest and down current of seafloor obstacles or within channels. Increased bottom current intensity contributed to the formation of regional seismic markers, first along the continental rise in the Early Oligocene, then along the continental slope during the Late Miocene and Pliocene. The timing of bottom current intensification appears to be similar to the record from the U.S. Atlantic margin. 3D seismic data show localized erosion surfaces that preserve along-slope seismic amplitude anomalies, barchan bedforms, and possible evidence of helical scour. 3D seismic data also allow determination of paleo bottom-current direction using multiple criteria. All bottom current evidence suggests a northeast-to-southwest, along-slope flowing Western Boundary Undercurrent (WBUC) during the Cenozoic. There is no preserved evidence of northward encroachment of the Gulf Stream or Gulf Stream Rings. Increased intensity of the WBUC in shallower water depths is interpreted to have occurred during the Miocene to Pliocene and possibly represents increased contribution from Labrador Sea water masses. It is clear that along-slope sedimentary processes were far more important in shaping the Scotian margin than previously understood.
Summary(Plain Language Summary, not published)
This abstract presents recent research on the evidence for bottom currents reworking the seabed off Nova Scotia during the last 40 Ma.

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