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Pelagic 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 Minimais constructed by Miniactinomyces chinensissp. no v. and the Admirabilisis built by Spirisosphaerospora pacificasp. nov.

Abstract: The Anqing-Lujiang quartz syenite rock belt consists of the Huangmeijian, Chengshan and Dalongshan composite batholiths which intruded into the Mesozoic strata. The country rocks were subjected to thermal contact metamorphism with little sign of folding and regional metamorphism. The rock belt is Late Yenshanian in age with a Rb-Sr isochron age of 135 Ma. Major rock types are quartz syenite and, to a lesser extent, syenite porphyry and alkali feldspar granite. Rock-forming minerals are dominantly potash feldspar (more than 50%) and lesser amounts of plagioclase and quartz. Mafic minerals, mostly Mg-biotite with lesser amounts of amphibole and pyroxene, are rare. Occasionally, alkalic mafic minerals (aegirine, riebeckite) are found. Characteristic accessary minerals of the earlier intrusives are magnetite, sphene and apatite and those of the later intrusives are ilmenite and zircon. Typologic distribution and evolutionary trend of zircon population are very similar to those of granites of mantle origin as suggested by Pupin, J. P. Petrochemically, the rock belt is poor in Ca but rich in alkali and Al with Na2O+K2O > 10%. It belongs to the K-Na transitional series, with a high alkalinity ratio (A. R. = 3–7) and a K /Na (atom) ratio close to unity. Rocks in the belt are rich in REE which tends to decrease from the early to the late stage, belonging to LREE type. The initial Sr ratio is 0.7078–0.7064. The rock belt is the Mesozoic anorogenic product of alkalic magmatic activity from a deep-seated source. According to a mantle-crust mixing model for Sr and Pb isotopes, it is estimated that 60.2–53.8% of the materials has been derived from the mantle. Additionally, its rich alkali, poor water content and anorogenic characteristics suggest that the belt is similar to the A-type granites.