TY - JOUR

T1 - Features of mineral crystallization at different stages of the magmatism evolution of the gorely volcano (Kamchatka): Data on melt and fluid inclusions

AU - Simonov, V. A.

AU - Dobretsov, N. L.

AU - Kotlyarov, A. V.

AU - Karmanov, N. S.

AU - Borovikov, A. A.

N1 - Funding Information: Authors thanks professor A.B. Perepelov and R.I. Kula-kov for the samples provided for the study, as well as to professor Y.A. Ozerov for the opportunity of sampling olivine-porphyric basalts. We also thank professors S.Z. Smirnov and M.G. Gavrilenko and all other specialists who participated in the discussion on research results on the Gorely volcano magmatism for critical remarks that helped to improve the quality of the article. The work was carried out on state assignment of the V.S. Sobolev Institute of Geology and Mineralogy SB RAS and the Trofimuk Institute of Petroleum Geology and Geophysics SB RAS, with the support of the Ministry of Science and Higher Education of the Russian Federation and project № 14.Y26.31.0029. Publisher Copyright: © 2021, V.S. Sobolev IGM, Siberian Branch of the RAS.

PY - 2021

Y1 - 2021

N2 - Studies of melt and fluid inclusions and minerals as well as computational modeling (based on the data on the composition of melt inclusions, clinopyroxenes, and amphiboles) gave an insight into the physicochemical parameters of magmatic systems during the evolution of the precaldera Pra-Gorely Volcano and during the subsequent formation of rock complexes of the Young Gorely Volcano. The estimated temperatures of crystallization of olivine, clinopyroxene, and plagioclase phenocrysts (1115–1260 ºС) and amphibole (740–890 ºС) are in agreement with the earlier published data on the magmatism of the Gorely Volcano. Computational modeling based on the compositions and homogenization temperatures of melt inclusions showed that the established depth interval of mineral crystallization (21.0–1.5 km) with pressures of 7.0–0.5 kbar can be divided into two ranges, 21–15 km and 9.0–1.5 km. Both the Pra-Gorely and Young Gorely volcanoes have magma chambers in these depth ranges. The Pra-Gorely Volcano is characterized by higher temperatures of mineral crystallization (1240–1190 ºС) as compared with the Young Gorely Volcano (1190–1125 ºС). The presence of primary fluid inclusions with low-density CO2 and of syngenetic primary melt inclusions in plagioclase of the Pra-Gorely Volcano indicates that the mineral crystallized from a heterophase melt. At the same time, the cores of plagioclase phenocrysts formed from a homogeneous melt. A drastic drop in pressure led to the phase separation of magma throughout the magma column (upper and lower chambers) and to the growth of zones saturated with CO2 fluid inclusions in the plagioclase crystals formed from a two-phase melt. The subsequent closure of the system and the disappearance of CO2 phase resulted in the growth of plagioclase from a homogeneous melt.

AB - Studies of melt and fluid inclusions and minerals as well as computational modeling (based on the data on the composition of melt inclusions, clinopyroxenes, and amphiboles) gave an insight into the physicochemical parameters of magmatic systems during the evolution of the precaldera Pra-Gorely Volcano and during the subsequent formation of rock complexes of the Young Gorely Volcano. The estimated temperatures of crystallization of olivine, clinopyroxene, and plagioclase phenocrysts (1115–1260 ºС) and amphibole (740–890 ºС) are in agreement with the earlier published data on the magmatism of the Gorely Volcano. Computational modeling based on the compositions and homogenization temperatures of melt inclusions showed that the established depth interval of mineral crystallization (21.0–1.5 km) with pressures of 7.0–0.5 kbar can be divided into two ranges, 21–15 km and 9.0–1.5 km. Both the Pra-Gorely and Young Gorely volcanoes have magma chambers in these depth ranges. The Pra-Gorely Volcano is characterized by higher temperatures of mineral crystallization (1240–1190 ºС) as compared with the Young Gorely Volcano (1190–1125 ºС). The presence of primary fluid inclusions with low-density CO2 and of syngenetic primary melt inclusions in plagioclase of the Pra-Gorely Volcano indicates that the mineral crystallized from a heterophase melt. At the same time, the cores of plagioclase phenocrysts formed from a homogeneous melt. A drastic drop in pressure led to the phase separation of magma throughout the magma column (upper and lower chambers) and to the growth of zones saturated with CO2 fluid inclusions in the plagioclase crystals formed from a two-phase melt. The subsequent closure of the system and the disappearance of CO2 phase resulted in the growth of plagioclase from a homogeneous melt.

KW - Gorely Volcano

KW - Intermediate magma chambers

KW - Kamchatka

KW - Melt and fluid (CO) inclusions

KW - Mineral phenocrysts in effusive rocks

KW - P–T conditions of magmatism

UR - http://www.scopus.com/inward/record.url?scp=85106291263&partnerID=8YFLogxK

UR - https://www.elibrary.ru/item.asp?id=46073162

U2 - 10.2113/RGG20194100

DO - 10.2113/RGG20194100

M3 - Article

AN - SCOPUS:85106291263

VL - 62

SP - 83

EP - 108

JO - Russian Geology and Geophysics

JF - Russian Geology and Geophysics

SN - 1068-7971

IS - 1

M1 - 6

ER -