Felsic magmas of the caldera-forming eruptions on the Iturup Island : the first results of studies of melt inclusions in phenocrysts from pumices of the Lvinaya Past and Vetrovoy Isthmus calderas. / Smirnov, S. Z.; Rybin, A. V.; Sokolova, E. N. et al.
In: Russian Journal of Pacific Geology, Vol. 11, No. 1, 01.01.2017, p. 46-63.Research output: Contribution to journal › Article › peer-review
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TY - JOUR
T1 - Felsic magmas of the caldera-forming eruptions on the Iturup Island
T2 - the first results of studies of melt inclusions in phenocrysts from pumices of the Lvinaya Past and Vetrovoy Isthmus calderas
AU - Smirnov, S. Z.
AU - Rybin, A. V.
AU - Sokolova, E. N.
AU - Kuzmin, D. V.
AU - Degterev, A. V.
AU - Timina, T. Yu
PY - 2017/1/1
Y1 - 2017/1/1
N2 - The paper reports the first results of the petrological studies of magmatic melts that formed siliceous pyroclastic deposits related to voluminous eruptions on Iturup Island. The caldera-forming eruptions of the Lvinaya Past and the Vetrovoy Isthmus, having similar features, resulted from the evolution of silicic melts that originated from partial melting of metabasalts. According to the mineral thermometry results, the melt was crystallized at ~800°C. The phenocrysts from the Vetrovoy Isthmus pumices were crystallized at <1 kbar, while those from the Lvinaya Past were formed at higher pressures. The pyroclastic rock compositions in both calderas correspond to moderately aluminous dacite and rhyolitic dacite of the normal series, whose melts likely did not undergo significant crystallization differentiation before the eruptions. The main volatile components of the magma include H2O, CO2, S, F, and Cl. Degassing with emission of water–carbon-dioxide fluid accompanied the early crystallization of plagioclase in the Vetrovoy Isthmus pumice. Evidence of pre-eruption melt degassing in the Lvinaya Past were not found. Water release from the melts may be related to both the early magma degassing and the eruptions. The lack of data evidencing the deep differentiation and mixing of contrasting melts implies a relatively small time period between the acid melt appearance and eruptions.
AB - The paper reports the first results of the petrological studies of magmatic melts that formed siliceous pyroclastic deposits related to voluminous eruptions on Iturup Island. The caldera-forming eruptions of the Lvinaya Past and the Vetrovoy Isthmus, having similar features, resulted from the evolution of silicic melts that originated from partial melting of metabasalts. According to the mineral thermometry results, the melt was crystallized at ~800°C. The phenocrysts from the Vetrovoy Isthmus pumices were crystallized at <1 kbar, while those from the Lvinaya Past were formed at higher pressures. The pyroclastic rock compositions in both calderas correspond to moderately aluminous dacite and rhyolitic dacite of the normal series, whose melts likely did not undergo significant crystallization differentiation before the eruptions. The main volatile components of the magma include H2O, CO2, S, F, and Cl. Degassing with emission of water–carbon-dioxide fluid accompanied the early crystallization of plagioclase in the Vetrovoy Isthmus pumice. Evidence of pre-eruption melt degassing in the Lvinaya Past were not found. Water release from the melts may be related to both the early magma degassing and the eruptions. The lack of data evidencing the deep differentiation and mixing of contrasting melts implies a relatively small time period between the acid melt appearance and eruptions.
KW - acid melts
KW - and Iturup Island
KW - caldera-forming eruptions
KW - calderas
KW - degassing
KW - melt inclusions
KW - melting
KW - metabasalts
KW - pumice
KW - pyroclastic rocks
KW - volatiles
KW - H2O
KW - DACITE
KW - SULFUR
KW - SOLUBILITY
KW - Iturup Island
KW - EVOLUTION
KW - SANTORINI
KW - ELECTRON-MICROPROBE ANALYSIS
KW - CONSTRAINTS
KW - CLIMACTIC ERUPTION
UR - http://www.scopus.com/inward/record.url?scp=85013074476&partnerID=8YFLogxK
U2 - 10.1134/S1819714017010080
DO - 10.1134/S1819714017010080
M3 - Article
AN - SCOPUS:85013074476
VL - 11
SP - 46
EP - 63
JO - Russian Journal of Pacific Geology
JF - Russian Journal of Pacific Geology
SN - 1819-7140
IS - 1
ER -
ID: 12949509