Summary for Field Activity Number 1981-033-FA

Alternate Leg ID: GYRE-81-14, Leg 1

Area of Operations: Long Island Platform, New York, Connecticut, United States, North America, North Atlantic

Dates: September 15, 1981 to September 26, 1981

Objectives: Define the extent and size of rift valleys identified in the basement surface of the LI Platform from USGS lines 24, 9, and 36 using the high-resolution multichannel system. Collect refraction velocity measurements within the rift structures and along undisturbed basement using the USGS OBIPs. Collect gravity data in the NY Bight, Raritan Bay, and NY Harbor to better define the shape and magnitude of the offshore extent of the Piedmont gravity high. Define the shape of the northern edge of the Baltimore Canyon Trough where it meets the LI Platform. Collect refraction velocity measurements along USGS Line 34 (continental slope) for a proposed ocean margin drill site. Test the resolution of the 240 m (12 channel) streamer with the 80 in3 watergun compared to the 120 m (12 channel) streamer and 15 in3 watergun. Do signature tests for the 540 in3 airgun, the 80 in3 watergun, the 40 in3 airgun, and the 15 in3 watergun.

Type of Activity: Sampling
Refraction data
Gravity data

Information to be derived: Samples and chemical analysis
Refraction data
Reflection data
Gravity data

Summary: Magnetic data: 15 km; Gravity data: 810 km (31 lines, 6 profiles); Seismic reflection data: 15 km of 12-channel, 247 km of 6-channel and 279 km of single-channel; Echo sounding data: 810 km of 3.5-kHz; Refraction profiles: 20 km of watergun and 94 km of airgun; Samples: 1 core and 3 grabs; OBIPs deployed: 13; OBIPs recovered: 12; Sonobuoys deployed: 4.

USGS Project Number: 9840-01830

Contact: Deborah Hutchinson (dhutchinson@usgs.gov)