Analysis of polymetallic micromineralization in pelagic sediments

Between Clarion and Clipperton Islands, the polymetallic precipitates are precocious and they are due to the submarine volcanic activity of this spreading zone; in spite of their small size, all the elements are concentrated in the precipitates: Mn (9-46%), Fe (0.2-11%), Ni (0.1-3.4%), Cu (0.1-1.7%), Co (0.1-0.8%).

The high internal structuration of micromineralisations, the splitting up of the elements in the laminations, the variability of contents according to the state of crystallinity can be explained by diagenetic processes at the scale of the grain. The contrast between the degree of evolution of these mineralisations and the situation of the area, that was submitted to important terrigenous and volcanic sedimentary inputs, lead to consideration of the micronodules as 'blocked structures', precursors of nodules, developed from diagenetic reactions of the micro-environment.