Восстановлена история формирования вулкана. Динамика его активности реконст­руирована в соответствии с абсолютной хронологической шкалой. Показано, что вулка­ническая активность имела пульсационный характер. Каждый период активизации ха­рактеризуется закономерной сменой состава вулканитов. Возраст собственно стратовулкана Безымянный составил около 5500 лет. Датированы крупнейшие пирокластические извержения. Подсчитан объем продуктов и средняя интенсивность выноса вещества за время жизни вулкана. Отмечено резкое возрастание интенсивности выноса вещества на современном этапе. Анализ реконструированной истории вулкана позволяет полагать, что его активность сохранится в ближайшие 200—300 лет.

Bolshaya Ipelka is a shield-shaped volcano, the largest among the units of this type in Kamchatka. The most typical mega-plagiophyre volcanites show that Th/U ratio for the rocks is equal to 3.6, though the standard value for Kamchatka Quarternary volcanites comprises about 1.5. The reason of the untypical content and, respectively, the ratio of these components might be oxidation and further migration of uranium. Conditions for this likely occurred in shallow circulating peripheral magma chambers not only at Ipelka, but to less extend at some other volcanoes with mega-plagiophyre variations of magmas.

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.