Summary Information for Field Activity 1975-033-FA

Area of Operations: South Texas inner continental shelf, Texas, Gulf of Mexico, United States, North America, North Atlantic

Dates: December 14, 1975 to December 18, 1975

Chief scientist: Henry Berryhill

Objectives: Cruise was devoted to acquisition of high quality high-resolution seismic reflection data and was a continuation of Leg 008 (FA 75030) following the same objectives: application of the land-use concept to the sea floor within Texas territorial waters (10.3 miles); acquisition of a detailed and integrated base of geologic data as background for the investigation of a variety of shoreline and inner shelf needs including shoreline engineering, power plant sitings, pipeline corridors, port sitings and determination of sediment movement and sand budget; general environmental assessment; and as a base for selecting sites for a variety of sampling types including grab, piston, vibracore and biological.

Type of Activity: Seismic profiling;

Information to be derived: Morphology;

Summary: Records obtained were of good to excellent quality. Several tie lines across the shelf were of unusually high quality, resolution of such detail that several key reflections representing Pleistocene low stands of the sea can be traced without equivocation from shelf edge to the 20 ft. isobath, the inner terminus of the lines. Minisparker: 800 km; 3.5 kHz: 300 km. Combined totals for Legs 008 (FA 75030) and 009 (FA 75033): Minisparker: 4140 km; 3.5 kHz: 1485 km. The Minisparker array was towed on starboard, the hydrophone streamer 150 ft. astern of the sparker tip. Pulse generator was fired at a 1.0 rep. rate. Signal from the hydrophones was split and transmitted through 2 signal processors to recorders at 1.0 sec. sweep and 0.5 sec. sweep. With the 3.5-7.0 kHz system, the 3.5 kHz range was used exclusively, recorded at a sweep rate of 0.5 sec. Time variable gain was used exclusively.

Contact: Henry Berryhill ()

InfoBank: uses the identifier F-9-75-GM. Visit this site for more information.

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