Identifier | 1971-005-FA | ||||||||
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Alternate names | UGEO Leg 5; CORPUS 20 | ||||||||
Purpose | The objectives of the geophysical and geological studies were to investigate the structural-stratigraphic framework of the continental margin adjacent to Liberia; to determine the nature of the transition from the pre-Cambrian shield area on land to the ocean floor; and to determine how deep sea fracture zones of the Atlantic Ocean tie to the continental shelf and to the continental geology of Africa. The cruise was divided into two main parts, geophysical profiling along the Liberian continental margin the first 17 days and dredging plus profiling the remaining 5 days of the cruise. | ||||||||
Location | Liberian continental margin, Liberia, Africa, North Atlantic; | ||||||||
Summary | With only shipboard examination of data, our results are preliminary and sketchy. 1. Pronounced magnetic anomalies on inner shelf are probably the seaward continuation of diabase intrusives on land, detected in aeromagnetic survey published by Behrendt and Wotorson. 2. A progradation of the shelf and slope along the central third of the Liberian continental margin. 3. Presence of a submarine canyon oblique to the coast off Cape Palmas. The same area is marked by steepened eroded slope, crumpling and faulting of strata, and marked gravity and magnetic anomalies. 4. A thick section of sedimentary rocks beneath much of the outer continental shelf, capped by gently dipping Pleistocene (?) terrace deposits at the shelf break. Sparker and 3.5 kHz profiles: 5400 km (37 tracklines); Sonobuoy refraction profiles: 5; Dredge stations: 7 (chain broke on last station, sample lost, dredge recovered); Magnetics; Gravity. | ||||||||
Info derived | Morphology; | ||||||||
Comments | Original Center People field contained: John Schlee - Ch. Sci.; James Robb - geologist; Charles O'Hara - geologist; Frank Jennings - ET. Project = International Decade of Ocean Exploration (IDOE), International Decade of Ocean Exploration (IDOE) | ||||||||
Related activities |
1971-001-FA: Cruise legs |
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Platform |
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Itinerary |
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Organization |
384 Woods Hole Road
Quissett Campus
Woods Hole, MA02543-1598
(508) 548-8700
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Principal investigators | John Schlee | ||||||||
Crew members |
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Affiliate staff | USGS-Denver: John Behrendt - geophysicist; USGS-Corpus Christi: Ray Martin - geologist; USGS-Menlo Park: James Pearl - Phys. Sci. Tech., William Todd - Phys. Sci. Tech., Harry Hill - ET, James Nicholson - ET; Liberian Geological Survey, Monrovia: Jenkins Dunbar - geologist; Spanish Institute of Geology and Mines of Spain, Madrid: Jaime Garcia-Rodriguez - geologist |
Data category: | Seismics, Electro-Magnetic, Sampling, Location-Elevation |
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Data type: | Air Gun / Water Gun, Boomer, Bubble Gun, Sparker, Sub Bottom Profiler, Magnetics, Gravity, Sonobuoy, Biology, Geology, Navigation |
Name | Description |
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Cruise report | Chief Scientist's cruise report of data collection and equipment notes, ship movement, personnel, data tabulations, etc. |
Equipment | Usage description | Data types | Datasets |
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Single channel hydrophone | Air Gun / Water Gun, Boomer, Bubble Gun, Sparker, Sub Bottom Profiler | 2 | |
Sparker | Sparker | (no data reported) | |
3.5 kHz | Sub Bottom Profiler | 2 | |
Marine magnetometer | Magnetics | 2 | |
Gravity meter (wh) | Gravity | 2 | |
Seismic refraction | Sonobuoy | (no data reported) | |
Dredge | Biology, Geology | (no data reported) | |
ITT 4007 satellite navigation | Navigation | 2 | |
Decca radar system | Navigation | (no data reported) |
Dataset name | Equipment | Description | Dataset contact |
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1971-005-FA-SE-001 | Single channel hydrophone | Collection of paper record displays of seismic data( SONO) for lines | Nancy K. Soderberg |
1971-005-FA-SE-002 | Single channel hydrophone | microfilm of | Nancy K. Soderberg |
1971-005-FA-BA-001 | 3.5 kHz | Bathymetric data in InfoBank | Nancy K. Soderberg |
NGDC MGD77 data | 3.5 kHz | Linda P McCarthy | |
1971-005-FA-GP-001 | Marine magnetometer | Magnetics in InfoBank | Nancy K. Soderberg |
NGDC MGD77 data | Marine magnetometer | Linda P McCarthy | |
1971-005-FA-GP-002 | Gravity meter (wh) | Gravity in InfoBank | William C Steele |
NGDC MGD77 data | Gravity meter (wh) | Linda P McCarthy | |
1971-005-FA-LN-001-01 | ITT 4007 satellite navigation | Navigation trackline plot for field activity 71005 | Nancy K. Soderberg |
1971-005-FA-LN-002 | ITT 4007 satellite navigation | Navigation data in InfoBank | Nancy K. Soderberg |