Abstract: Geotechnical Properties of Upper Continental Slope Sediments, Eastern United States

Adrian F. Richards

Six borings, to a maximum depth below the seafloor of about 300 m, were made during the 1976 U.S. Geological Survey's Atlantic Margin Coring Project. Three of these borings had sufficient geotechnical information, obtained from shipboard and ashore testing, to warrant discussion: hole 6004, southeast of Charleston, South Carolina, in predominantly calcareous sediments of Pleistocene to Cretaceous age; hole 6021, east of Atlantic City, New Jersey, in Pleistocene silty clays; and hole 6017, north of Georges Bank, in Pleistocene sandy and silty clays.

Geotechnical properties of sediments cored in the two northern holes showed small changes with depth and were generally similar in range; specific gravity, 2.6 to 2.7; bulk density, 1.8 to 2.0 mg/cu m; water content, 20 to 70% dry weight; liquid limit, 25 to 65%; plastic limit, 15 to 30%; shear strength, 5 to 80 kPa; and sensitivity, 2 to 7. Most geotechnical properties in the southern hole were distinctly different in range: bulk density was lower, water content higher, Atterberg limits much higher, and sensitivity presumedly higher. Sedimentation-compression e log p curves showed a variable relation of consolidation with respect to burial depth for the sediments of the southern hole, and a more constant relation for the northern holes. The upper-slope sediments from the northern loc tions contrast in their geotechnical properties with nearby continental shelf sediments; differences are inconsistent in the two locations.

AAPG Search and Discovery Article #90961©1978 AAPG Annual Convention and Exhibition, Oklahoma City, Oklahoma