various magmatic rocks having common structural, mineralogical-petrographic, petrochemical, and geochemical properties, which allow them to be considered products of a single magmatic source. The term “comagmatic rocks” was introduced by the American petrographer and geo-chemist H. S. Washington in 1906. Comagmatic rocks form during a single tectonic-magmatic cycle, and ordinarily there is a rock gradation with later magma being more acidic and containing more alkalis, volatile components, and ore elements. The distinguishing traits of different comagmatic rocks are caused by differentiation, assimilation, and hybridization and by the geological and physicochemical conditions in which the formation of the comagmatic rocks occurred. Various intrusive, subvolcanic, and effusive rocks are included among comagmatic rocks.
REFERENCESAfanas’ev, G. D. “Granitoidy drevnikh intruzivnykh kompleksov Severo-Zapadnogo Kavkaza.” Tr. In-ta geologicheskikh nauk AN SSSR, 1950, no. 69.
Rub, M. G., B. V. Makeev, and G. L. Vasil’eva. “Kriterii komagmatichnosti intruzivnykh, subvulkanicheskikh i eífuzivnykh porod na primere Miao-Chanskogo raiona.” Izv. AN SSSR: Ser. geologicheskaia, 1964, no. 1.
Washington, H. S. The Roman Comagmatic Region. Washington, 1906. (Carnegie Institution of Washington. Publication no. 57.)