QUATERNARY SEDIMENTARY PROCESSES ALONG THE U.S. ATLANTIC CONTINENTAL MARGIN FROM THE SHELF TO THE ABYSSAL PLAIN
As part of marine geohazard and UN Convention on the Law of the Sea studies, we have been reexamining the sedimentary processes responsible for the recent evolution of the U.S. Atlantic continental margin. Open-slope and confined submarine landslides and submarine canyon/channel/fan systems have been identified and/or entirely remapped along the margin from the shelf edge down to abyssal depths (using multibeam bathymetry, backscatter/sidescan, and seismic reflection data). Submarine landslides and debris flows are ubiquitous along the margin, with some transporting more than 100 km3 per event and modifying tens of thousands of square kilometers of seafloor. Shelf-breaching and slope confined canyons dissect the U.S. Atlantic margin from the shelf to abyssal depths (>4000 m), coalescing at depth into a number of discrete canyon systems (e.g., Oceanographer-Lydonia, Hudson, Wilmington-Baltimore, Norfolk-Washington, Hatteras) that eventually transition into broad, low-relief submarine fans. Deep-water contour currents have also been active along the U.S. Atlantic margin since the Oligocene and continue to actively shape the region today. The Hatteras, Blake-Bahama and now buried Chesapeake contourite drift systems are the clear manifestation of the along-slope processes, but we also find evidence of bottom-current influence on seafloor morphology and sedimentation at almost all depths, and various scales, along the margin. New interpretations arising from this work will provide the basis for comprehensive reevaluation of latitudinal and temporal drivers of margin evolution.