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

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