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Late Quaternary history of contourite drifts and variations in Labrador Current flow,Flemish Pass,offshore eastern Canada |
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| Authors: | Nicole R Marshall David J W Piper Francky Saint-Ange D Calvin Campbell |
| Institution: | 1. Department of Earth Sciences, Dalhousie University, Halifax, NS, B3H 4R2, Canada 3. Virginia Institute of Marine Science, College of William and Mary, Gloucester Point, VA, 23062, USA 2. Geological Survey of Canada, Bedford Institute of Oceanography, Dartmouth, NS, Canada |
| Abstract: | Contourite drifts of alternating sand and mud, shaped by the Labrador Current, formed during the late Quaternary in Flemish Pass seaward of the Grand Banks of Newfoundland, Canada. The drifts preserve a record of Labrador Current flow variations through the last glacial maximum. A high-resolution seismic profile and a transect of four cores were collected across Beothuk drift on the southeast side of Flemish Pass. Downcore and lateral trends in grain size and sedimentation rate provide evidence that, between 16 and 13 ka, sediment was partitioned across Beothuk drift and the adjacent Flemish Pass floor by a strong current flow but, from 29 to 16 ka, sedimentation was more of a blanketing style, represented by draped reflections interpreted as being due to a weaker current. The data poorly resolve the low sedimentation rates since 13 ka, but the modern Labrador Current in Flemish Pass is the strongest it has been in at least the past 29 ka. Pre-29 ka current flow is interpreted based on reflection architecture in seismic profiles. A prominent drift on the southwestern side of Flemish Pass formed above a mid-Miocene erosion surface, but was buried by a mass-transport deposit after the penultimate glacial maximum and after drift deposition switched to eastern Flemish Pass. These findings illustrate the temporal complexity of drift sedimentation and provide the first detailed proxy for Labrador Current flow since the last glacial maximum. |
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