Summary Information for Field Activity 1975-017-FA

Area of Operations: Georges Bank, United States, North America, North Atlantic

Dates: September 02, 1975 to September 22, 1975

Chief scientist: Mike Bothner
Bill Dillon

Objectives: The main purpose of the cruise was to collect cores of sediment up to 20 feet long to provide lithology and age of the subsurface sediments. Sampling locations were selected to correlate with geophysical information obtained on a later cruise to this area by this office. A number of special studies were also carried out: 1. Collection of suspended matter at the surface and bottom of the water column to determine total concentration, mineralogy, trace metals, and special characteristics as determined with a scanning electron microscope; 2. collection of hydrostatically damped gravity cores to determine vertical variability of trace metals and hydrocarbons in undisturbed near-surface sediments; 3. collection of grab samples at replicate stations to statistically determine the within-station and within-sample variability on Georges Bank; 4. placement of reference stakes in the bottom with the vibracore apparatus or on the bottom with a railroad wheel anchor to serve as a long-term monitor of sediment accumulation and/or erosion at specific localities; 5. seismic profiling, especially in areas of the reference pipes, to determine present day forms at the sediment surface.

Type of Activity: Sampling; Seismic profiling; Sea floor mapping;Sea floor mapping

Information to be derived: Samples and chemical analysis; Suspended sediment concentrations; Sea floor map;

Summary: Although all objectives were completed satisfactorily, this cruise was plagued with equipment failures necessitating a return to port on 2 occasions and loss of 6 sea days. Stations: 27; Bottom sediment samples: 68 (Vibracores: 21; Hydrostatically-damped gravity cores: 35; Smith-McIntyre grab samples: 12); Suspended Sediment Samples: 42 (2 m below surface: 20; 2 m above bottom: 22); Reference pipes emplaced: 5 (Stakes in sediment: 2; Stakes with railroad wheel base and pingers: 3); 3.5 kHz sonar and sidescan sonar: 83 km; Minisparker: 300 km.

Contact: Mike Bothner (mbothner@usgs.gov)
Bill Dillon (bdillon@usgs.gov)

InfoBank: uses the identifier F-1-75-GK. Visit this site for more information.

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