Abstract: Atlantic Margin Coring Project, 1976--Summary of Operations and Results

John C. Hathaway

The U.S. Geological Survey Atlantic Margin Coring Project, 1976, a 60-day expedition to obtain core samples by drilling beneath the floor of the continental shelf and slope of the eastern United States, was carried out in July, August, and September 1976 aboard D/V Glomar Conception. Twenty-nine holes penetrated as much as 300 m below the seafloor at 20 sites along the continental margin from Georgia to Georges Bank off New England in water depths ranging from 20 to 300 m; 1,020 m of material ranging in age from Late Cretaceous to Holocene were recovered in 385 cores.

One of the major findings of the program includes the discovery of fresh water (salinities less than 3 parts per thousand) extending beneath the continental shelf as much as 111 km seaward from the New Jersey coast. Fresh water of potable quality (about 1 part per thousand) was found beneath the shelf more than 13 km off Ocean City, Maryland, and Barnegat Inlet, New Jersey.

Analyses for light hydrocarbons in the cores show the highest concentrations at sites in water depth greater than 200 m (the shelf-slope break). Concentrations greater than 400,000 ppm were found in two of these sites. Maximum concentrations of methane occurred principally in Pleistocene sediments on the continental slope.

AAPG Search and Discovery Article #90968©1977 AAPG-SEPM Annual Convention and Exhibition, Washington, DC