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Convergent processes of microplates have not been fully clarified yet, however, they are fundamentally common with those of major plates. Convergent processes of major plate, in particular those related to subduction of oceanic plate, are briefly reviewed on the basis of modern and ancient subduction-accretion complexes. Bio-and lithostratigraphically reconstructed oceanic plate stratigraphy, composed of MORB basalt, pelagic and hemipelagic sediments, and coarse-grained terrigenous clastics in ascending order, is critical in determining the time of accretion and age of subducted oceanic plate. Such criterion is well applicable to microplate tectonics. Development of microplate is not capable of forming major orogens but it is effective in modifying pre-existing orogenic arrangement. The Nankai fore-arc sliver in Southwest Japan, for example, is a tectonic modifier which rearranged the Late Paleozoic to Cenozoic Cordilleran-type orogenic edifice of Southwest Japan. Some geologic phenomena such as dextral strike-slip motion of the Median Tectonic Line and abrupt termination of the Sanbagawa belt in east Kyushu are best explained by the westward motion of the Nankai fore-arc sliver.
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Japanese WESTPAC Symposium. June 6-7, 1989. Ocean Research Institute, University of Tokyo. 西太平洋におけるマイクロプレートテクトニクスと古環境地図に関する研究会. 1989年6月6日-7日. 東京大学海洋研究所.
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