花崗岩系列の提唱と発展  [in Japanese] A proposal and development of granitoid series concept  [in Japanese]

The greatest contribution to the granite petrology during the last decade would be the proposition of the granitoid series: magnetite-series, ilmenite-series, I-type, M-type and A-type. The magnetite-series granitoids are characterized by the presence of magnetite and high Fe^<3+>/Fe^<2+> whole-rock ratio and crystallize under the oxidized condition; the ilmenite-series granitoids are characterized by the lack of magnetite and low Fe^<3+>/Fe^<2+> whole-rock ratio and solidify under the reduced environment; the former are closely related in their magma genesis to the igneous rocks oxidized on the earth's surface and the latter to the crustal materials containing crustal carbon. The I-type granitoids are characterized by the occurrence of Ca-bearing mafic minerals, such as hornblende, and low K_2O/Na_2O, Al_2O_3/(Na_2O+K_2O+CaO) and high C/(ACF) whole-rock ratios and the S-type granitoids by the presence of aluminous minerals, such as cordierite, garnet, Al_2SiO_5 minerals and muscovite, and high K_2O/Na_2O, Al_2O_3/(Na_2O+K_2O+Ca_O) and low C/(ACF) whole-rock ratios; the I-types are contributed by the igneous rocks in their magma genesis and the S-types by the pelitic sedimentary rocks. The M-type granitoids show lower K_2O/Na_2O, K_2O/SiO_2 and higher CaO/(Na_2O+K_2O) whole-rock ratios than the I-types; the low alkali nemafic igneous rocks of the upper mantle origin are closely related to the generation of the M-type granitic magma. The A-type granitoids are often accompanied by the felsic igneous rocks of the alkali rock-series and characterized by the high alkali and low H_2O (anhydrous) contents; they generally occur in the extensional tectonic field. The distinction of the granitoid series makes it possible to know more concretely about the nature of the crustal materials related to the generation of granitic magmas. The granitoid series has been employed as a tool for mineral exploration, because they are closely associated with particular metal deposits. Japanese geologists have played an important role on the establishment of the granitoid series.