National Centers for Environmental Information (NCEI)
University of Texas-Institute for Geophysics
SOUTHWEST ATLANTIC IPOD SITE SURVEYS
Data Announcement 83-MGG-09
Approximately 2,072-line km of 3- and 12-fold multichannel common
depth point (CDP) seismic data for offshore
Brazil. The data were collected by the University of Texas
Institute for Geophysics during 2 cruises of Research Vessel FRED
M. MOORE in July 1979 as part of its Southwest Atlantic IPOD
(International Phase of Ocean Drilling) Site Survey. Data were
gathered to define the geologic and geophysical setting for
proposed IPOD drilling sites.
Data acquisition during the first cruise originated in the Hunter
Channel area and approximately 1,035-line km of 6-trace 3-fold
data (23 lines) are available. A 600-m streamer was used as the
receiver and the sound source consisted of an array of three Bolt
(R) airguns firing simultaneously at 500 psi. On some lines, 5/8-
lb maxipulse charges served as the high-resolution profiling
source. The airgun lines were recorded as filtered multiplexed
data on a DFS-4 system at a 4-ms sampling rate and the maxipulse
data at a 2-ms rate. The multichannel data were supplemented by
continuous 12-kHz precision depth recordings. Total field
magnetic intensity measurements were made with a Varian(R) proton
precession magnetometer. The CDP seismic data are available as
full-scale copies (Scale: 2.5 in/sec). Other geophysical data
are available on 35-mm microfilm or magnetic tape.
Data acquired during the second cruise in the northern Argentine
Basin area consists of approximately 1,035-line km of 24-trace 12-
fold data (41 lines). A 1,200-m streamer was used as the
receiver for both the airgun and the maxipulse lines. Velocity
analyses for the CDP seismic data collected during this part of
the cruise are available on 1 reel of 35-mm microfilm. 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.
1. Common Depth Point Seismic Data: 3- and 12-fold data for 64
lines (full-scale). Available in plastic sepia, paper sepia,
2. Other Geophysical Data: includes sparker, profiler magnetics
on 2 rolls of microfilm (Nos. 1845 and 1846). Available in
3. Velocity Analyses - 1 roll of microfilm (No. 1847 - WSA lines
only). Available in 35-mm microfilm.
4. Track Charts (scale: 4 in/degree) available in plastic
sepia, paper sepia, and blackline.
Merged navigation, magnetics and bathymetry data are available on
1 magnetic tape, 9-track, 1,600 bpi, and ASCII. This is also
available on CD-ROM.