National Geophysical Data Center
GEOCHEMICAL AND GRAIN-SIZE DATA
U.S. Mid-Atlantic Outer Continental Shelf and Slope
USGS Data Sets AT16293 & AT16298
Geochemical and grain-size data are now available for surface sediment and water samples taken from the U.S. Mid-Atlantic Outer Continental Shelf and slope. Sample collection was done by Ocean/Seismic/Survey, Inc., and geochemical and grain-size analysis were performed by Texas Instruments, Inc., under contract to the U.S. Geological Survey (USGS) Conservation Division. These data were collected to aid the evaluation of geologic structures in the Lease Sale No. 49 area, and were provided by the USGS to the National Geophysical Data Center (NGDC) for public dissemination.
Lease Sale No. 49 was the second sale on the Mid-Atlantic Outer Continental Shelf blocks within this sale cover 774,273 acres (313,344 hectares) and extend farther north, south and seaward than those of the first sale, OCS Lease Sale No. 40 (USGS data set AT-15384), with which they are interspersed. the blocks of Lease sale No. 49 are located 80 to 160 km offshore from New York to Virginia in water depths of 35 to 1,425m.
The data included concentrations of low-molecular weight hydrocarbons (methane through pentane) in 1,242 surface sediment samples, and methane and ethylene content of interstitial water from the sediment and 500 water samples. Sand percentage is given for the sediment samples, and a detailed breakdown of grain-size distribution is provided for 657 samples containing less than 75 percent sand-size or coarser grains.
Samples were collected on a 1-mile grid form 234 blocks on federal acreage offshore from New Jersey, Delaware, Maryland, and Virginia.
DESCRIPTION OF DATA
The following items are being released:
1. Three base maps at a scale of 1 in = 8,000 ft showing locations in relation to numbered blocks of Lease Sale No. 49.
2. Technical report describing sampling operations and listing site locations and water depths.
1. Technical report on the geochemical and grain-size analysis of samples, including detailed description of analytical techniques, references and bibliography.
2. Tables of analytical data--190 pages of the results of geochemical and grain-size analysis.
Geophysical data for Lease Sale No. 49 are described in NGDC Flier 1978 (P-P). These data are still available for distribution as are geophysical data from the overlapping Lease Sale No. area described in NGDC Flier 1979 (V).
Summary information and scanned images of the reports are available through the marine geology inventory.