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Geomorphic characterization of four shelf-sourced submarine canyons along the U.S. Mid-Atlantic continental margin

Deep-Sea Research Part II: Topical Studies in Oceanography

By:
, , , , , and
DOI: 10.1016/j.dsr2.2013.09.013

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Abstract

Shelf-sourced submarine canyons are common features of continental margins and are fundamental to deep-sea sedimentary systems. Despite their geomorphic and geologic significance, relatively few passive margin shelf-breaching canyons worldwide have been mapped using modern geophysical methods. Between 2007 and 2012 a series of geophysical surveys was conducted across four major canyons of the US Mid-Atlantic margin: Wilmington, Baltimore, Washington, and Norfolk canyons. More than 5700 km2 of high-resolution multibeam bathymetry and 890 line-km of sub-bottom CHIRP profiles were collected along the outer shelf and uppermost slope (depths of 80-1200 m). The data allowed us to compare and contrast the fine-scale morphology of each canyon system. The canyons have marked differences in the morphology and orientation of canyon heads, steepness and density of sidewall gullies, and the character of the continental shelf surrounding canyon rims. Down-canyon axial profiles for Washington, Baltimore and Wilmington canyons have linear shapes, and each canyon thalweg exhibits morphological evidence for recent, relatively small-scale sediment transport. For example, Washington Canyon displays extremely steep wall gradients and contains ~100 m wide, 5–10 m deep, v-shaped incisions down the canyon axis, suggesting modern or recent sediment transport. In contrast, the convex axial thalweg profile, the absence of thalweg incision, and evidence for sediment infilling at the canyon head, suggest that depositional processes strongly influence Norfolk Canyon during the current sea-level high-stand. The north walls of Wilmington, Washington and Norfolk canyons are steeper than the south walls due to differential erosion, though the underlying cause for this asymmetry is not clear. Furthermore, we speculate that most of the geomorphic features observed within the canyons (e.g., terraces, tributary canyons, gullies, and hanging valleys) were formed during the Pleistocene, and show only subtle modification by Holocene processes active during the present sea-level high-stand.

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Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Geomorphic characterization of four shelf-sourced submarine canyons along the U.S. Mid-Atlantic continental margin
Series title:
Deep-Sea Research Part II: Topical Studies in Oceanography
DOI:
10.1016/j.dsr2.2013.09.013
Volume
104
Year Published:
2013
Language:
English
Publisher:
Elsevier
Contributing office(s):
Woods Hole Coastal and Marine Science Center
Description:
14 p.
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
Larger Work Title:
Deep-Sea Research Part II: Topical Studies in Oceanography
First page:
106
Last page:
119
Country:
United States
Other Geospatial:
Cape Hatteras;Georges Bank;Hudson Canyon