Seabed Assessment Program 



This program's objective is to investigate geological proc- 

 esses along continental margins, mid-ocean ridges, and deep- 

 ocean basins. These processes form hydrocarbon and metallic 

 ores and concentrate them into economically significant de- 

 posits. The projects supported by Seabed Assessment are 

 broadly grouped as Continental Margin Studies, Plate Tec- 

 tonics and Metallogenesis Studies, and the Manganese Nodule 

 Study. Specifically, on going projects include: 



1. African Atlantic Margin Study 



2. Southwest Atlantic Continental Margin Study 



3. Mid- Atlantic Ridge Study 



4. Galapagos Spreading Center Study 



5. Nazca Plate Study 



6. Studies in East Asia Tectonics and Resources (SEA 

 TAR) 



7. Manganese Nodule Study 



Projects of this large a scale require cooperation among 

 several institutions and nations. The pattern commonly fol- 

 lowed has three parts: synthesis of available data, field pro- 

 gram for acquisition of new data, and finally, data synthesis 

 and publication of results. The projects selected must have 

 specific goals. They are designed to be completed in a specific 

 time period ranging from 3 or 4 years to as long as 8 or 9 

 years. As will be indicated later, each phase of the project 

 employs different techniques and instruments suitable to a 

 logical development, usually with increasing size and sophisti- 

 cation. Moreover, more than one topic may be investigated in 

 the same geographic location. For example, in the Nazca 

 Plate and East Asia Projects, both continental margins and 

 metallogenesis are subjects of inquiry. In the program to in- 

 vestigate the origin and distribution of manganese nodules, a 

 single topic is investigated in a wide variety of ocean environ- 

 ments. 



Continental Margin Studies 



Continental margins are broadly divided between passive 

 (pull-apart) and active (compressive) types. The South At- 

 lantic Ocean is characterized by passive margins that have 

 formed through geological times as Africa "pulls apart" from 

 South America along the Mid-Ocean Ridge. Conversely, the 

 Pacific Ocean "is closing" as the land masses around the 

 circum-Pacific converge along its active margins. Studies along 

 the south Atlantic margins were completed in 1976. In a 

 series of recently published scientific papers, attention has 

 been focused on the environments of sedimentary deposition 

 and the structural features that controlled their distribution. 

 Particular attention was given to identify the conditions 

 favorable for the formation and entrapment of oil. 



African Atlantic Mai^in 



This comprehensive geophysical and geological survey 

 from Capetown to Portugal fills a major gap in our world-wide 



knowledge of continental margins. Although specific problems 

 remain to be investigated, a broad framework has now been 

 established. K. O. Emery, who served as chief scientist on the 

 project, and others have published major papers in the "Bulle- 

 tin of the American Association of Petroleum Geologists." 



Southwest Atlantic Continental Margin 



A project along the coasts of Argentina and Brazil com- 

 plementary to the African Atlantic Margins Study, was also 

 completed in 1976. Groups of scientists from Lamont-Doherty 

 Geological Observatory (L-DGO) gathered geological and 

 geophysical data from the Scotia Arc, which lies between South 

 America and Antarctica to the northeast coast of Brazil ad- 

 jacent to the Caribbean. Geological field work was done on 

 the islands of South Georgia and the southern-most Andes in 

 cooperation with Antarctic investigations by United Kingdom 

 scientists. Another group of scientific investigators from the 

 Woods Hole Oceanographic Institution (WHOI) investigated 

 the continental shelf of Brazil. Lamont, Woods Hole, and 

 Brazilian scientists cooperated on a geological and geophysical 

 study of the Amazon Cone. On a cooperative basis, Argentine, 

 Brazil, and Chilean geologists participated in these cruises that 

 took place along their respective continental margins. 



The results of these investigations have been published 

 in a series of papers. The large-scale geophysical and geological 

 studies appear in Geodynaniics, vol. 19, Continental Margins 

 of the Atlantic Type, published as vol. 48 "1976 Annals of 

 the Brazilian Academy of Sciences." 



Continental Margin Data 



Continental Margin Data are available from NGSDC as 

 follows : 



University of Texas at Galveston-J. Watkins, 420 n.m. 

 of multi-channel (24 track) seismic data profiles on mylar. 

 (See fig. 27.) 



Continental Margin Bibliography 



Damuth, J. E. 1973. Sedimentation on the north Brazilian 

 continental margin. Cong. Brasileiro de Geologia, Anais, 

 26th, p. 43-50. 



Emery, K. O., F. Lepple, L. Toner, E. Uchupi, R. H. Rioux, 

 W. Pople, and E. M. Hurlburt. 1974. Suspended matter 

 and other properties of surface waters of the northeastern 

 Atlantic Ocean. J. Sedimentary Petrology 44: 1087-1110. 



Emery, K. O., J. D. Milliman, and E. Uchupi. 1973. Physical 

 properties and suspended matter of surface waters in the 

 southeastern Atlantic Ocean. J. Sedimentary Petrology 

 43: 822-837. 



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