| Title | Geophysical evidence for bottom current activity throughout the Cenozoic from the continental margin off Nova Scotia, Canada |
| |
| Author | Campbell, D C ;
Mosher, D C |
| Source | Geological Association of Canada-Mineralogical Association of Canada, Joint Annual Meeting, Programs with Abstracts vol. 35, 2016 p. 20 |
| Image |  |
| Year | 2016 |
| Alt Series | Earth Sciences Sector, Contribution Series 20130460 |
| Publisher | Geological Association of Canada |
| Meeting | Geological Association of Canada (GAC) and the Mineralogical Association of Canada (MAC) Joint Annual Meeting; St. John's; CA; May 27-29, 2013 |
| Document | serial |
| Lang. | English |
| Media | paper; on-line; digital |
| File format | pdf |
| Province | Eastern offshore region |
| Area | Scotian Margin |
| Subjects | sedimentology; marine geology; stratigraphy; sediment transport; sedimentation; marine sediments; bottom sediments; sediment dispersal; submarine features; seismic data; erosion; bottom currents;
Western Boundary Undercurrent (WBUC); Cenozoic |
| Program | Offshore Geoscience |
| Abstract | The 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. |
| GEOSCAN ID | 293663 |
|
|