VOLCANISM OF THE SOUTHERN PART OF THE SREDINNY RANGE OF KAMCHATKA IN THE NEOGENE-QUATERNARY
A.O. Volynets1, M.M. Pevzner2, M.L. Tolstykh3, A.D. Babansky4
1Institute of Volcanology and Seismology, Far Eastern Branch of the Russian Academy of Sciences, bul’v. Piipa 9, Petropavlovsk-Kamchatsky, 683006, Russia
2Geological Institute, Russian Academy of Sciences, Pyzhevskii per. 7, Moscow, 119017, Russia
3Vernadsky Institute of Geochemistry and Analytical Chemistry, Russian Academy of Sciences, ul. Kosygina 19, Moscow, 119991, Russia
4Institute of Geology of Ore Deposits, Petrography, Mineralogy and Geochemistry, Russian Academy of Sciences, Staromonetnyi per. 35, Moscow, 119017, Russia
Keywords: Субдукция, обогащенная мантия, флюид, островодужный вулканизм, внутриплитный вулканизм, гибридный вулканизм, задуговая зона, Камчатка, Срединный хребет, Subduction, enriched mantle, fluid, island-arc volcanism, within-plate volcanism, hybrid volcanism, back-arc, Kamchatka, Sredinny Range
Abstract
Based on the geochemical characteristics of the Miocene-Quaternary volcanic rocks of the Sredinny Range of Kamchatka, we divide it into northern and southern provinces; the latter comprises the «eastern», «western», and «central» flanks. We present new data on the composition of Neogene-Quaternary volcanic rocks in the southern part of the Sredinny Range of Kamchatka: Khangar and Icha volcanic massifs and Mt. Yurtinaya on the «western» flank, Bystrinsky and Kozyrevsky Ridges on the «eastern» flank, and Anaunsky Dol and Uksichan massif located in between. We show systematic differences in the composition of rocks from the «western» and «eastern» flanks. During the Neogene, a typical island-arc volcanism took place within the «eastern» flank. Quaternary volcanic rocks of this area have both island-arc and within-plate geochemical features. We propose to call rocks of this type hybrid rocks. Within the «western» flank, hybrid volcanism has been manifested since the Neogene, while typical island-arc rocks are not found. Magma generation processes on the «western» flank of the Sredinny Ridge are influenced by the enriched mantle source; the effect of fluid is less pronounced here as compared to the rocks of the «eastern» flank, where it is clearly traced.
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