Alternate Leg ID: FAY 021
Area of Operations: Mid-Atlantic Continental Margin, North Atlantic Continental Margin, United States, North America, North Atlantic
Dates: August 28, 1976 to September 07, 1976
Objectives: Primary objectives were to look for geophysical evidence for the continuation of fracture zones from the Mesozoic sea-floor spreading anomalies into the continental margin, investigate the source of lineated magnetic anomalies in the Jurassic Quiet Zone, and obtain additional seismic data on the continental rise and slope.
Type of Activity: Seismic profiling
Information to be derived: Morphology
Summary: FAY departed Woods Hole the afternoon of August 28, delayed 2.5 days awaiting a new crew. We steamed around the west end of Martha's Vineyard and deployed the airgun, magnetometer and minisparker at a point south of the channel between Martha's Vineyard and Nantucket. Most tracks were run perpendicular to the continental margin for better coverage of the continental slope/rise area. At the end of Line 21-4, we pullled in the airgun and magnetometer and steamed along the edge of the continental shelf (Line 21-5) to the mouth of Wilmington Canyon. Dave Twichell conducted a 1-day sidescan sonar survey of the sand waves at the mouth of the canyon. The USGS ORE sidescan system worked remarkably well from the beginning. Unfortunately LORAN-C navigation was extremely bad and final navigation was based on bridge LORAN-A. After departing Wilmington Canyon, we headed into deep water for one final traverse parallel to the continental margin. At this point USGS-Woods Hole contacted us to conduct a sidescan survey on the edge of Georges Bank where the drill ship GLOMAR CONCEPTION had lost the on-floor drill assembly. The water depth was too deep for the sidescan cable and could get only 50 fathoms from the bottom; we could see nothing. It was very difficult to survey at slow speeds because of fast currents. We returned to Woods Hole with only the minisparker deployed and arrived about noon, Sep. 7, 1976. Gravity: 2885 km; Airgun: 2150 km; Magnetics: 2150 km; Minisparker: 2750 km; 3.5 kHz: 140 km; Sidescan sonar: 140 km.
USGS Project Number: EA-RA
Contact: Kim Klitgord ()