The Gabbro–Granodiorite Magmatic Complex of the Kronotsky Paleoarc (Eastern Kamchatka): Composition, Age, and Tectonic Position

• Published in: Geotectonics
• Main Authors: Tsukanov, N. V., Luchitskaya, M. V., Portnyagin, Maxim V., Savelyev, D. P., Soloviev, A. V., Hourigan, J. K.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Springer 2022
• Subjects: Kamchatka
• Online Access: https://oceanrep.geomar.de/id/eprint/57556/; https://oceanrep.geomar.de/id/eprint/57556/1/S0016852122050089.pdf; https://doi.org/10.1134/S0016852122050089

New U‒Pb (LA-ICP-MS) geochronological data have been obtained on accessory zircons from granodiorites and on detrital zircons from stream-sediment samples from the Shipunsky massif in the Eastern Kamchatka region. The age of accessory zircons from amphibole–biotite granodiorites has been estimated at 49–44 Ma. Detrital zircons have the Late Paleocene–Early Eocene age from ~57 to ~49 Ma. Based on the geological and geochronological data, the massif was formed in two stages: a gabbroid intrusion (56‒51 Ma) and the quartz diorite-granodiorite intrusion (49‒44 Ma). In terms of the petrographic and geochemical characteristics of the Upper Cretaceous–Eocene volcanic rocks in the Shipunsky Peninsula and granitoids in the Shipunsky massif, they were formed in the suprasubduction setting. The Shipunsky granitoids belong to the I-type granites. The Shipunsky massif was formed as a part of the Kronotsky intraoceanic paleoarc during the Paleocene–Eocene in two stages. The southern segment of the Kronotsky paleoarc collided with the Kamchatka continental margin and the deformed rocks of this massif were brought to the surface.