Seabed Assessment Program 



This program is designed to increase understanding of 

 the geologic processes active along the continental margins, 

 midoceanic ridges, and deep ocean basins. These processes 

 generate the raw material of modern industrial civilization — pe- 

 troleum and heavy metals. Since the obvious, near-surface de- 

 posits of natural resources have already been found and are 

 being depleted at a high rate, new deposits must be located. 

 The Seabed Assessment Program aims at understanding geologic 

 processes and deriving new principles and new models of the 

 earth that the resource geologist should find valuable in plan- 

 ning more detailed exploration studies. The projects supported 

 by IDOE do not duplicate the efforts of oil and mining compa- 

 nies. Seabed Assessment Program scientists are investigating 

 the Atlantic continental margins, Mid-Atlantic Ridge, and bas- 

 ins of the Gulf of California, as well as the processes involved 

 in plate tectonics and metallogenesis. They also convened a 

 workshop on ocean minerals. 



Continental Margins Studies 



The purpose of the conti^ental margin studies is to under- 

 stand the origin and evolution of the present day margins and 

 to reconstruct the geological conditions at each stage in the sea 

 floor spreading of the South Atlantic. The data obtained will 

 facilitate the interpretation of relationship between the fracture 

 zones and the thick accumulation of sediments, as well as 

 between the aseismic ridges and the deposition of massive salt 

 formations. Moreover, the existence of multimillion barrel oil 

 fields beneath the continental shelves cannot be explained by 

 present day geological conditions. 



Both sides of the Atlantic are being investigated simulta- 

 neously. All major geophysical and geological measurement 

 techniques are being used. K. O. Emery, Woods Hole Oceano- 

 graphic Institution (WHOI), is serving as chief scientist aboard 

 the WHOI Atlantis ii investigating the zone from South Africa 

 to Portugal, and from the African coast to the Mid-Atlantic 

 Ridge. The field work will be completed this year. J. Milliman, 

 WHOI. is serving as chief scientist on a project supported by 

 the Brazilian government with emphasis on the location of 

 detrital minerals. G. Bryan is serving as coordinator for a team 

 of Lamont-Doherty Geological Observatory (LDGO) scien- 

 tists whose studies extend from the Scotia Arc to the Carib- 

 bean. I. Dalziel, LDGO, is carrying out complementary geo- 

 logical investigations on the island of South Georgia. Field 

 work will continue through 1975. 



WHOI and LDGO scientists are publishing results as 

 they become available. One major goal of this cooperative 

 effort will be a series of paleogeographic maps, one for each 

 successive opening of the South Atlantic Ocean. A preliminary 

 stratigraphic correlation chart for Africa and South America is 

 also planned. Reconstruction of geological conditions in this 

 area where the fit of the continents is relatively straightforward 



should be applicable to other more complex parts of the world. 



The first phase of a 4-year program to study the geology 

 and geophysics of a relatively unknown area of the Atlantic 

 Ocean floor between Western Africa and the Mid-Atlantic 

 Ridge was successfully concluded in July 1972. From January 20 

 to July 1, 1972, the WHOI RV Atlantis ii completed nearly 

 50,000 trackline kilometers of geological and geophysical sur- 

 veying on 7 legs between Port Elizabeth, Republic of South 

 Africa, and the Congo River (figure 26) with particular em- 

 phasis on the continental margin. 



During these cruises, continuous profiles were made with 

 simultaneous recordings of bathymetry at 3.5 kilohertz, seismic 

 reflection, refraction using sonobuoys, gravity, and magnetics. 

 Navigation was primarily by satellite supplemented by radar and 

 other methods near the coast. Five computers aboard ship 

 permitted rapid processing of the geophysical data on a 24- 

 hour interval both as superimposed profiles as well as in map 

 form, so that readjustments of subsequent traverses could be 

 made to provide the best coverage of geological structures. 



This initial cruise yielded interesting information on deep 

 ocean geology including the Cape Agulhas Fracture Zone, as 

 well as another major unnamed fracture zone, the Walvis 

 Ridge, and the stratigraphy of Cape Agulhas and the Angola 



Figure 26. — Geological and geophysical survey 

 Unes of WHOI's RV ATLANTIS II, January 20 

 to July 1, 1972. 



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