iid 
BLAKE 
PLATEAU 
PROVINCE —=~ @ 
—< 
PROVINCE 
0° 
| 4 
2 80° 60° 40° 20° 
FIGURE 5 
Ferromanganese deposits of the North Atlantic. Both the Blake Plateau and Red Clay Provinces are sites of 
non-deposition or very low sediment accumulation. Cores and dredges from areas outside these provinces 
which recovered ferromanganese are from the flanks and summits of topographic highs. 
= 
SOUTH cs = | 
AFRICA 2 
AMERICA ¢ MADAGASCAR oe | 
BASIN 
PROVINCEe b 20° 
~ S ~ | 
a = 
@ CAPE 
= 
AGULHAS 
PLATEAU 
PROVINCE 
wiP-ATLANTIC RIDGE 
e 
+ ~ °. 4 
=<— ——q DREDGE 
° @ CORE 
———lso" 
—= 
=* e® e 
a i eee — 1 
o 207 40° 7 10° 
FIGURE 6 
Distribution of ferromanganese deposits in the South Atlantic and Western Indian Oceans. The South American Province, and Cape, Mad- 
agascar and Crozet Basins are areas protected from continental and biogenic debris. Rates of sedimentation are low and nodules are 
abundant. 
Source, Figs. 5 and 6: Horn e¢ al., 1972, op. cit., p. 11. 
NORTH PACIFIC OCEAN 
The richest deposits of manganese nodules are found in the North 
Pacific Ocean in a narrow band south of Hawaii just north of the 
equatorial zone of high biological productivity (Fig. 3). This band is 
about 200 km wide by 1500 km long and runs roughly east-west between 
latitudes 6° N and 20° N and between longitudes 110° W and 180° W. 
The ocean floor is 4000 to 5000 m deep in this area and the sediments 
are rich in siliceous remains of plankton (radiolaria). The floor of 
the North Pacific where nodules occur can be divided into two types: 
siliceous ooze and red clay. The average metal values of nodules from 
the siliceous deposits are nickel (Ni) 1.28 percent, copper (Cu) 1.16 
