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National Centers for Environmental Information (NCEI)

University of Texas-Institute for Geophysics


Mississippi Cone and Florida Shelf - NE Gulf of Mexico

Data Announcement 84-MGG-14

     Approximately 970 nmi of 12-fold Common Depth Point (CDP) seismic-reflection data for purchase from the National Geophysical Data Center (NGDC) (now the National Centers for Environmental Information (NCEI)) for the northeastern Gulf of Mexico (see centerfold illustration). The data were collected during the June and July 1976 by the University of Texas Marine Science Institute Research Vessel IDA GREEN under contract to the Naval Coastal Systems Laboratory (NCSL), as part of certain acoustic and seismic propagation tests in the vicinity of Panama City, Florida. The data were gathered to provide NCSL with fundamental data from which determinations of the geology, acoustical properties, and seismic-wave velocities beneath the propagation paths can be made. As part of the geophysical measurements program, bottom cores were taken along some seismic reflection tracklines. The University of Texas has provided these data to NGDC (now NCEI) for public dissemination.

     Data were sampled and recorded at 4-msec intervals on a Texas Instruments DFS 10,000 system with a 70-kHz hi-cut filter. The sound source consisted of up to 4 Nobl-Bolt R MAG 4200 airguns, each having a capacity of 1,500 cu. in. per gun at a pressure of 500 psi. The hydrophone array consisted of 24 300- ft groups with a total length of approximately 8.000 ft. The multichannel data were supplemented by continuous single-channel seismic reflection profiling and 3.5 kHz precision-depth recording. These are available on 35-mm microfilm. Velocity- depth profiles are available for each of the seismic lines shown as solid lines. Seventy-five sediment cores were obtained at 75 stations along the seismic tracklines. A total of 1,451 ft of 2- 3/8-in. diameter core was obtained, making the average core length 19.36 ft. Descriptions of these cores are available as paper copies or as microfiche (see NGDC Data Announcement 82-MGG- 08, Index to Marine Geological Samples "The Core Curator's File").

     The seismic data are available as full-scale copies (scale: 2.5 in./sec). Navigation, bathymetry, and magnetics data are available for all lines on magnetic tape or CD-ROM.


1. Common-Depth Point Seismic Data:
       24-Fold multichannel seismic data for 5 lines, 26 sections (full scale) available in plastic sepia, paper sepia, and blackline.

2. Other Geophysical Data:

       1 Reel 35-mm Microfilm (No. R209) (contains 3.5 kHz, 12-kHz, sparker profiler records, and navigation plots)

       1 Microfiche contains velocity depth profiles

3. Merged navigation, magnetics and bathymetric data are available in MGD77 format on 1 magnetic tape or CD-ROM.

       Navigation chart available in plastic sepia, paper sepia, and blackline.

4. Core descriptions are available as:
       Computer Listings, photocopies (637 pages-2 volumes), and 6 microfiche.

       (Please refer to Data Set 82-MGG-08) when ordering core description data)