Рассмотрено образование различных типов магматических пород с использованием для расшифровки их генезиса геологических, петрографических и петрохимичсских методов, а также данных по экспериментальному изучению фазовых равновесий в породах. Уделено внимание распределению редких элементов в горных породах и изотопному анализу. Дана оценка возможностей и применимости различных методов исследования. Обоснована ведущая роль магматической дифференциации в генезисе изверженных пород. Освещены вопросы методологии их изучения.

Для геологов, петрографов и других специалистов, занимающихся изучением изверженных пород и связанных с ними полезных ископаемых. Может быть полезна студентам вузов геологического профиля.

Isotope-geochemical material for Pliocene-Quaternary volcanoes of the Kamchatka region is generalized on a cartographic basis. The Sr-isotope anomalies of moderate and elevated radiogenicity, geochemically confirmed, are spatially conjugated. This made it possible to interpret these anomalies not only as a reflection of mantle plume material in the composition of volcanic rocks, but also of its hybrid environment, as a consequence of plum-lithosphere remobilization. The presence of multi-directional geochemical trends made it possible to propose the concept of moving boundary values for the composition of indicator rocks of the intraplate type and adakites, which significantly expanded the possibilities of their diagnostics. The isotope-geochemical heterogeneity of basaltoids of the region is generally determined by the peculiarities of concentration of rocks with intraplate and adakite geochemical characteristics, which allows considering the asthenospheric diapirism as the main factor of petrogenesis of Pliocene-Quaternary volcanism in Kamchatka.

The paper presents new geological and isotope-geochemical data on rock composition from the head of the Kikhchik River, the outer NW part of Miocene-Pliocene volcanic belt of Central Kamchatka. The authors obtained age characteristics (40K−40Ar dates): 9.8 and 9.1 Ma for Kecheva massif and 8.3 and 7.8 Ma for Aopchi cones. New data on ages and analytical materials allow substantial updating our understanding of the rock composition from this volcanic belt as well as the beginning of volcanic activity. The authors revealed complex rocks, both completely identical to closely located volcanic manifestations (Kecheva) and abnormally enriched with Rb, Pb, Ba, Zr, Hf, Nb, U, Th and radiogenic Sr Aopchi, Kabanikha, littoral cones. The origin of these anomalous volcanites was likely caused by the partial melting of the mantle source close to the Sp- peridotite metasomatically reworked by the processes that may relate both to dehydratation of the subducting oceanic plate, and by the effect from the asthenospheric diapir.

The paper presents the data on age, mineralogy, geochemistry, and isotope composition of rocks from the
Bolshoi Payalpan Volcano (Sredinny Range, Kamchatka). We compared these data with those on the Nosichan
and Belogolovsky volcanoes, located within the Belogolovsky volcanic center. The basalts of the neck and the
upper lava complex of Bolshoi Payalpan are compositionally similar to the intraplate-type trachybasalts of the
Belogolovsky Volcano, and the basaltic andesites of the lower lava and the cone complex are similar to the
island arc rocks of the Nosichan Volcano. Analysis of the data obtained evidences that spatial and temporal
manifestations of intraplate and island-arc volcanism at the Bolshoi Payalpan Volcano are not accidental, but may
be a consequence of a change in the degree and depth of melting of the same deep source with the involvement
of a mantle diapir. The Belogolovsky volcanic center formed in a setting of the Late Miocene-Early Pliocene
rifting. Its evolution, right up to its extinction, proceeded in the same geodynamic setting with an increase in
depth of the mantle source and a decrease in the degree of its melting. Rock compositions of the Lower-Middle
Pliocene Nosichan Volcano remain of the island-arc type under conditions of rifting, since they are associated
with the mantle reservoir located at a shallower depth, which has experienced a higher degree of melting. There
is good reason for considering large volcanic centers as spontaneously-developing geological entities. As the
endogenous activity dies down, the degree of melting decreases and the depth of melting increases with the
replacement of island-arc volcanism by intraplate volcanism. The volcanic center becomes extinct.

Дается описание своеобразных пород субщелочного основного и среднего состава, распространенных в Срединном хребте Камчатки. Эти породы характеризуют вулканические, интрузивные и метасоматические образования, объединяемые авторами в единую вулкано-плутоническую формацию трахиандезит-габбро-сиенитового состава. Исходной магмой авторы считают базальтовую повышенной щелочности. Результаты петрографических работ, проведенных за последние годы в пределах Срединного хребта Камчатки, позволяют выделить в пределах его зону распространения своеобразных пород субщелочного состава.

Авторами настоящей статьи кратко описываются своеобразные пироксен-ортоклазовые метасоматические породы, приуроченные к области экзоконтакта порфировидных кварцевых сиенитов, прорывающих интрузив ультраосновных пород.