FORMATION OF THE EAST KAMCHATKAN ACCRETIONARY PRISMBASED ON FISSION-TRACK DATING OF DETRITAL ZIRCONSFROM TERRIGENE ROCKS
A.V. Solov'ev, M.N. Shapiro*, J.I. Garver**, and A.V. Lander***
Institute of Lithosphere of Marginal and Inner Seas of the RAS, 22 Staromonetny per., Moscow, 119180, Russia
* United Institute of Physics of the Earth, 10 ul. Bol'shaya Gruzinskaya, Moscow, 123810, Russia
** Geological Department, Union College, Schenectady, New York, USA
*** International Institute of Earthquake Prediction Theory and Mathematical Geophysics of the RAS,79 Varshavskoe Shosse, Bldg. 2, Moscow, 113566, Russia
Keywords: Fission-track dating, zircon, tectonic evolution, East Kamchatkan accretionary prism
Pages: 1237-1247
Abstract
Fission-track ages were determined from detrital zircons from sandstones of the Drozdov and Stanislavskaya Formations and Tyushev Series of the Kumroch Range, eastern Kamchatka. The age of the young zircon population in the sandstones of the Drozdov Formation (Kumroch Range) is late Late Paleocene (from 55.9  4.4 to 57.7 3.5 Ma). The Drozdov Formation was deposited in the late Paleocene and continued to accumulate in the Early Eocene. The age of young zircon populations in the coarse-clastic sequence of the Stanislavskaya Formation (40.7 3.1; 40.9 3.9; 42.4 1.9 Ma) indicates that it accumulated as late as middle Bartonian. The age of young zircon populations in the sandstones of the Tyushev Series (from 50.0 2.9 to 38.1 3.4 Ma) is much older than the age of the sandstones themselves (Early-Middle Miocene, 24-11 Ma). Therefore, in the Early Miocene, the Tyushev Series accumulated a distance from central Kamchatka, volcanic activity was intense at that time. There are three tectonic zones within the East Kamchatkan accretionary prism: Stanislavskaya, Vetlovaya, and Tyushev. The Stanislavskaya zone, represented by terrigenous units, are interpreted as deposits of the accretionary prism that originated after the Ozernoe-Valagin arc collided with the Eurasian margin. The Vetlovaya zone was formed by offscraping cover strata from the oceanic crust that separated the Ozernoe-Valagin and Kronotsky arcs in the middle Paleocene to late Miocene. Deposits of the Tyushev zone formed the Oligocene-Miocene cover of the |
