Geological Structural Position of Late Miocene–Pliocene Alkaline Magmatism of Eastern Kamchatka

• Main Authors: M. K. Bakhteev, S. R. Tikhomirova
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Subjects: Aleutian Island; Kamchatka
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.621.1167; http://g-to-g.org/pdf/bakhteev_tikhomirova_sverdlov_1995eng.pdf

Eastern Kamchatka encompasses the northern part of the Kuril-Kamchatka island arc and western flank (Kamchatskii Mys) of the Aleutian island arc. A vast literature is devoted to the structural position of Late Pliocene–Quaternary volcanism of this region. The geological structural position of earlier Late Miocene–Early Pliocene volcanogenic formations remains much less studied. Discovered among the latter are a few occurrences of alkaline-subalkaline rocks that differ sharply from typical island arc formations [12]. They are situated in a region with mafic [V. I. Shul’diner et al., 1981] continental crust and gravitate toward the western flank of the Eastern Kamchatka volcanic belt, which part of the modern island arc system. The well-known solitary occurrence on the eastern flank of the belt in the immediate vicinity of the seismic focal zone [13] has been supplemented by new finds [14, 15, 16]. The occurrences are represented by flows, nappes, and sills of alkaline and subalkaline basalt confined to the basal terrigenous portion of the Late Miocene–Quaternary volcanogenic cross section and also comagmatic subvolcanic dikes, sills, and small stocks of teschenites, essexites, camptonites, and trachydolerites, which are bedded among older sequences of the island arc accretion basement and comprise the root feeder system of volcanic structures [4, 14