Pelagic Manganese Nodules—A New Type of Oncolites

AbstractPelagic manganese nodules from the East Pacific Ocean have been studied using polarizing, scanning electron and transmission electron microscopes. It has been revealed that the manganese nodules are composed of cores and stromatolite coatings. The structures and textures of these nodules are peculiar to oncolite. Consequently, the pelagic manganese nodules are manganese oncolites. Based on the stromatolites in the coatings, the manganese oncolites from the East Pacific Ocean can be divided into two types. One is smooth on surface and dense inside. Its coatings are composed mainly of Minima. The other has a knobby surface and is loose internally. Its coatings consist mainly of Admirabilis. The TEM investigation has also revealed that the constructors of the manganese oncolites are ultra–microbes. The Minima is constructed by Miniactinomyces chinensis sp. no v. and the Admirabilis is built by Spirisosphaerospora pacifica sp. nov.