U.S. Law of the Sea Cruise to Map the Foot of the Slope of the Northeast U.S. Atlantic Continental Margin: Leg 7

TitleU.S. Law of the Sea Cruise to Map the Foot of the Slope of the Northeast U.S. Atlantic Continental Margin: Leg 7
Publication TypeReport
AuthorsArmstrong, AA, Calder, BR, Smith, SM, Gardner, JV
Department NameCenter for Coastal and Ocean Mapping/Joint Hydrographic Center
Number of Pages58
Date PublishedJuly 17
Organization NameCenter for Coastal and Ocean Mapping / Joint Hydrographic Center
LocationDurham, NH
KeywordsAtlantic Margin, Law of the Sea, Ron Brown

This report details the 2012 Atlantic Extended Continental Shelf (ECS) bathymetry mapping cruise for the U.S. Extended Continental Shelf Project. This cruise is the seventh ECS cruise to map the U.S. Atlantic continental margin. The 2012 cruise was planned after analyses of the 2004, 2005 and 2008 bathymetry demonstrated that gravity-driven down-slope transport of terrigenous sediments in some regions of the Atlantic margin extends much farther to the east than was previously documented. Consequently, the 2012 cruise focused on mapping the extent of the down-slope sediment transport at the base of the lower continental margin.

The Office of Ocean Exploration and Research, National Oceanic and Atmospheric Administration (NOAA) made available a 30-day window in the schedule of the NOAA Ship Ronald H. Brown for the 2012 mapping cruise. The Ronald H. Brown is an 84.5 m (274 ft) 3250 ton multipurpose oceanographic research vessel with a hull-mounted Kongsberg EM122 multibeam echo sounder (MBES). JHC/CCOM leased a Knudsen 3260 3.5- kHz chirp sub-bottom profiler for the cruise because the ship does not have an adequate deepwater subbottom profiler. A deep-water subbottom profiler was required to image the top 50± m of the sediment layer to aid in the identification of deposits of sediment that have been transported by gravity (down-slope) processes.

NOAA personnel aboard the ship were responsible for system maintenance and real time data management. UNH CCOM/JHC personnel were responsible for cruise planning, a patch test of the EM122 MBES, data (MBES, subbottom and water column sound speed) collection and quality control and data processing of the MBES bathymetry and acoustic backscatter and subbottom data. The cruise collected and mapped a total area of 69,287 km2.