ABSTRACT
Pelagic manganese nodules from the East Pacific Ocean have been studied by electron microscopy, paleontology and mineralogy. The results show that they are composed of core and coatings, and the coatings are manganese stromatolites. Based on lamina shape, column shape and its branching and coalescing, two forms of stromatolites, namely Minima and Admirabilis, have been identified. They can be seen in the coatings of smooth and knobbly nodules respectively. It has been revealed from TEM studies that these manganese stromatolites have been constructed by the ultra-microfossils. According to the morphology of the hyphae two species of ultra-microfossils, Miniactinomyces chinensis and Spirisosphaerospora pacifica, have been identified. Miniactinomyces chinensis and Spirisosphaerospora pacifica were sessile benthic microorganisms living in completely darkness on rocky or other solid substrate. The scattered occurrence, presence of various cores, radial growth and some other features can be explained by biogenic formation of the pelagic manganese nodules. They are not a product of either crystallization or sedimentation directly from the sea-water and have been formed as a result of the rhythmic growth of the ultra-microbes.
