Ch. 2— Resource Assessments and Expectations • 75 



Figure 2-13.— Potential IHard lUlineral Resources of U.S. Insular Territories South of Hawaii 



Many 

 seamounts 



Wake Island 



Horizon 

 Guyot 



Seamounts 



seamounts 



Loihi 



Submarine 



Volcano 



Johnston Island 



Seamounts 



Seamounts Howland and 

 Baker Islands 



Seamounts 



Palmyra Atoll 

 Kingman Reef 



/ 



© 



Prime manganese 



nodule province 



(not U.S. territory) 



Jarvis Island 



Seamounts 



\i 



Explanation 



Known Likely 



occurrence occurrence 



Mn-nodules (4) 



Co-crusts (?) 



Massive sulfides (e^ 



Submarine volcanism 



American Samoa 



— Seamounts 



••Q J 



■'«■ 



L 



X 



500 



_L_ 



1000 Miles 

 _l 



SOURCES: Office of Technology Assessment, 1987; U.S. Department of tlie Interior, "Symposium Proceedings— A National Program for the Assessment and Develop- 

 ment of the Mineral Resources of the United States Exclusive Economic Zone," U.S. Geological Survey Circular 929, 1983. 



area that could not be mined because of roughness 

 of small-scale topography. When asked to place the 

 stage of knowledge of the economic potential of co- 

 balt crusts on the time-scale experienced in the in- 

 vestigations of manganese nodules, one leading 

 researcher chose 1963.^' 



^'J.M. Broadus, Seabed Mining, report to the Office of Technol- 

 ogy Assessment, U.S. Congress, Feb. 14, 1984, p. 24. 



Manganese Nodules 



Ferromanganese nodules are found at most water 

 depths from the continental shelf to the abyssal 

 plain. Since the formation of nodules is limited to 

 areas of low sedimentation, they are most common 

 on the abyssal plain. Nodules on the abyssal plain 

 are enriched in copper and nickel and, until re- 

 centiy, have been regarded as candidates for com- 

 mercial recovery. Nodules found on topographic 

 highs in the Pacific are enriched in cobalt and were 

 mentioned in the previous section. 



