Atlantic Margin Coring Project 1976: Preliminary Report on Shipboard and Some Laboratory Geotechnical data

Open-File Report 78-123
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Abstract

This report presents reduced shipboard geotechnical data collected during the 1976 Atlantic Margin Coring Project; results of laboratory tests of specific gravity, water content, bulk density, and Atterberg limits; and sedimentation-compression e log p curves showing consolidation. A description of the procedures used at sea and in the laboratory and a short preliminary summary of the shipboard results also is included.

The involvement of Marine Geotechnical Laboratory (MGL), Lehigh University, personnel in the 1976 Atlantic Margin Coring Project can be divided into two phases. In Phase One, the Lehigh nuclear-transmission densitometer was rebuilt to process cores at sea more rapidly than previously had been done in the laboratory, the equipment was assembled and tested aboard the Glomar Conception, and at-sea geotechnical measurements were made during the duration of the cruise.

Data sheets were prepared for both unopened core sections (Appendix III) and split-core samples (Appendix IV). Completed data forms are on file at the MGL and at the Geological Survey in Woods Hole.

Phase Two included reduction of the shipboard data, testing of all geotechnical samples taken from cores split aboard the ship, and certain other analytical work ashore utilizing the geotechnical measurements. Water content and weight/volume bulk density tests were performed at the MGL. Specific gravity and Atterberg limit tests and certain calculations were performed by Geological Survey personnel at the Corpus Christi, Texas, laboratory.

During Phase One, 37 unopened, 1.5-m-long core sections were selected by Lehigh personnel for subsequent static and dynamic triaxial and consol­idation testing ashore. The disposition of these cores is controlled by Geological Survey Project personnel; they are not further discussed in this report.

A depth convention has been adopted in this report for the convenience of labeling core sections and analyzing the data. Each 9.2-m-long (30 ft) core liner had a maximum penetration depth referenced to the water-sediment interface; these data are given in Hathaway, et al. (1976). Each 9.2-m-long core liner was cut into six or fewer sections, each 1.5 m (5 ft) in length, aboard the ship. To the maximum penetration depth, 0.2 m was subtracted to obtain the depth at the bottom of the first 1.5 m section above the core catcher. To obtain values at the bottom of the remaining 1.5 m sections, an additional 1.5 m was added for each section. The depth of the bottom of each core section was used for all values obtained using the nuclear densitometer. Tests within core sections and samples collected from core sections were assigned depths based on the location of the test or sample within the core section. It should be clearly recognized that all depths within a 9.2-m-long core are estimates of the true depth, which cannot be uniquely calculated because of the uncertainty of the relationship of sediment contained within the core liner to true in situ depths.

This report is considered to be preliminary because the author has not had access to the final lithologic logs or paleontological results, upon which a more accurate description of geotechnical results could be based. It would be inappropriate to comment on geological hazards until this information is made available.

Suggested Citation

Richards, A.F., 1977, Atlantic Margin Coring Project 1976—Preliminary report on shipboard and some laboratory geotechnical data: U.S. Geological Survey Open-File Report 1978-123, 165 p., https://pubs.er.usgs.gov/publication/ofr78123.

ISSN: 2331-1258 (online)

Study Area

Table of Contents

  • Foreword 
  • Introduction 
  • Core quality evaluation
  • Shipboard geotechnical tests
  • Laboratory geotechnical tests
  • Downhole density logging
  • Sedimentation-compression curve analysis
  • Results 
  • References
  • Appendices

Additional publication details

Publication type Report
Publication Subtype USGS Numbered Series
Title Atlantic Margin Coring Project 1976: Preliminary Report on Shipboard and Some Laboratory Geotechnical data
Series title Open-File Report
Series number 78-123
DOI 10.3133/ofr78123
Year Published 1977
Language English
Publisher U.S. Geological Survey
Publisher location Reston, VA
Contributing office(s) Coastal and Marine Geology Program
Description 165 p. in various pagings :ill. ;28 cm.; (166 p. - PGS)
Country United States
Other Geospatial Atlantic Ocean
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