National Centers for Environmental Information (NCEI)

University of Texas-Institute for Geophysics

SOUTH ATLANTIC IPOD SITE SURVEYS
African Margin and Mid-Atlantic Ridge

Data Announcement 83-MGG-07

Approximately 2,300-line km of 12-fold common depth point (CDP) data for the continental margin off southwest Africa. The data were collected by the University of Texas Institute for Geophysics during three cruises of Research Vessel FRED H. MOORE in the Spring of 1979 as part of South Atlantic IPOD (International Phase of Ocean Drilling) Site Surveys. Data were gathered to define the geologic and geophysical setting for proposed IPOD drilling sites.

A 48-trace, 2.8-km streamer was used as a receiver and the sound source consisted of four modified Bolt (R) 1,500 cu. in. airguns simultaneously fired at 500 psi. Incoming data were digitally sampled at 4-ms intervals, filtered (6-62 Hz), and recorded in multiplexed format. The airgun profiles were supplemented by continuous 3.5/12 kHz data. Total field magnetic intensity measurements were made with a Varian (R) proton precession magnetometer.

CDP seismic data for the African Margin phase are available as full-scale copies (scale: 2.5 in/sec), of 87 sections for 41 lines. Seismic data for the Mid-Atlantic Ridge is 3-trace data, not CDP processed, and is available only as 35-mm microfilm copies. Other shipboard geophysical data are also available on micro-film. Merged navigation, magnetics, and bathymetry can be obtained on 9-track magnetic tape. The University of Texas has provided these data to the National Geophysical Data Center (NGDC) (now the National Centers for Environmental Information (NCEI)) for public dissemination.

DATA AVAILABILITY

1. Common Depth Point Seismic Data: 12-fild data for 87 lines (African Margin only) full-scale. Available in plastic sepia, paper sepia, and blackline.

2. Other Geophysical Data: includes 12 kHz data, sparker profiler, and magnetics on 5 rolls of microfilm: (Nos. 1835-1839). Available in 35-mm microfilm.

3. Velocity Analyses - 4 rolls of microfilm: (Nos. 1840-1843). Available in 35-mm microfilm.

4. 5 Track Charts (scale 4"/degree) available in plastic sepia, paper sepia, and blackline.

Merged Navigation, magnetics, and bathymetry are available on 1 magnetic tape, 9-track, 1600 bpi, and ASCII. This is also available on CD-ROM.