Radiolarian oozes

Figure 20.1 illustrates that the major sediment type on the abyssal plains are the abyssal clays with some local exceptions, including equatorial radiolarian oozes, manganese nodifles, and metalliferous sediments. 

Manganese Nodules Fields on the Radiolarian Ooze Belt in the Central Pacific 117... 

In this chapter the manganese nodule fields on the radiolarian ooze in the Central Pacific will be described in detail. These manganese nodules fields are the richest yet known in the world so that they have b n the subject of a great deal of re rch. Prolmbly, the first raising of manganese nodules as ore will take place in this area. 

The radiolarian ooze belt is situated in the North Central Pacific between the Clarion and Clipperton fracture zones, about 10°-20 °N and 120°-160 °W. The reason why the radiolarians are sedimented there is a corresponding oceanic current in the surface water, in which radiolarians have optimal conditions for their growth. 

The radiolarians settle down on the sea floor together with terrestrial clay particles creating the radiolarian ooze . The radiolarian tests have a very fragile neat... 

Fig. 13. Radiolarians and radiolarian fragments separated from the sediment from radiolarian ooze belt.

Fig. 14. Different particles occurring in radiolarian ooze Black micronodules, patchy clay aggregates, glassy sharp dged fragment volcanic ash. (Clay aggregates can partly be formed as weathering products of volcanic ash or partly be new built).

Fig. 15. I junded manganese micronodules separated magnetically from radiolarian ooze. They usually r ergrow radiolarians or clay mineral aggregates.

In this way, manganese nodules growing on the radiolarian ooze belt are supplied from two sources vrith metals needed for their growth from the sea-water with iron-rich material and from the pore-water with manganese-rich materia). 

The deep-sea radiolarian ooze is a biologically active zone as we could observe by the bioturbation of the sediments. Thus, the question arises how far the biologic processes can influence the growth of manganese nodules. 

The best mining area known so far is the radiolarian ooz belt in the Central Pacific. Pearson reported the following average composition of nodules for this... 

The whole Pacific Ocean floor contains 1.5 trillion tons of manganese nodules but the percentages of commercially useful metals are lower for the average of the total Pacific than in the radiolarian ooze area. 

CaCOa < 30 %. > 30 % siliceous fossils diatom or radiolarian ooze... 

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