Summary for Field Activity Number 1975-002-FA

Alternate Leg ID: ATL2 89-1; 89, Leg 1

Area of Operations: mid-Atlantic outer continental shelf, Baltimore Canyon trough area, United States, North America, North Atlantic

Dates: April 13, 1975 to April 28, 1975

Objectives: Conduct a geology and geophysics cruise along the Atlantic continental margin between Virginia and Cape Cod, concentrating on the continental shelf and slope between Virginia and Long Island where high-resolution seismic reflection profiling, vibracoring and bottom samples are needed for Bureau of Land Management (BLM) and USGS environmental impact studies in areas where petroleum lease sales are being considered. Single-channel seismic reflection profiles (airgun), gravity, and magnetics (Legs 1-3) programs for regional geologic resource assessment studies will also be conducted. Leg 1 was designed to obtain eight long geophysical lines across the continental shelf, slope and rise between Virginia and Cape Cod.

Type of Activity:

Information to be derived:

Summary: Collected 8 long geophysical profiles across the margin from the inner continental shelf to the lower continental slope between Virginia and Cape Cod. Systems employed included airgun reflection (single-channel), high-resolution seismics (minisparker, Uniboom and 3.5 kHz sonar), gravity, and a magnetometer. Four of the lines provided potential field and high-resolution seismic data where 24- and 48-channel seismic profiles were available. The other four lines are in locations where the USGS expects to obtain new multichannel lines during 1975 and 1976. Although hampered and delayed by three major storms, the AII was able to complete the planned grid on schedule. 3.5 kHz records: 3,750 km; Gravity profiles: 3,750 km; Magnetic profiles: 3,050 km; Airgun profiles: 2,400 km; Minisparker: 600 km; Uniboom profiles: 50 km.

USGS Project Number: RA-EA

Contact: John Grow ()