Summary for Field Activity Number 1974-015-FA

Alternate Leg ID: KNKE BLM-Leg Charlie; CORPUS 24/30

Area of Operations: south Texas outer continental shelf, Texas, United States, Gulf of Mexico, North America, North Atlantic

Dates: November 29, 1974 to December 21, 1974

Objectives: The overall program is a baseline assessment of the South Texas Outer Continental Shelf. Objectives of the geological studies being carried out under the program by the USGS are: nature and distribution of bottom sediments, nature of suspended sediments in the water column, trace metals chemistry of sediments; late Pleistocene and Holocene structural and sedimentologic evolution of the shelf; delineation of surface areas of the shelf where geologic conditions might be hazardous to petroleum development; and predictive evaluation to the extent possible of the possible effects of the physical and chemical processes operative across the shelf on the dispersion and assimilation of contaminants that might be generated by petroleum development.

Type of Activity: Sampling
Seismic profiling

Information to be derived: Samples and chemical analysis
Morphology

Summary: Patterns on the acoustic profiles that are believed to be gas seeps were recorded at a number of places on the shelf (most numerous on the outer edge of the shelf). Extensive faulting exists over most parts of the South Texas OCS. The submerged reefs, or so-called topographic highs, are but the exposed part of extensive thin carbonate banks buried by sedimentation. Smith-MacIntyre grabs: 40; Gravity cores: 13; Box cores: 32; Benthic faunal collections: 72; XBTs: 12; Surface drifter casts: 36 (3 at each of 12 stations); Quality control sample for trace metals: 6; Hydrocarbon back-up sample: 32; Water samples for suspended sediments: 9 (3 at each of 3 stations); Minisparker: 1,000 mi.; 3.5 kHz profiles: 1,400 miles; 12 kHz PDR; Klein Model 400 sidescan sonar: approx. 400 miles.

USGS Project Number: STEX-OCS

Contact: Henry Berryhill ()