Pre-eruptive storage conditions of the Holocene dacite erupted from Kizimen Volcano, Kamchatka

Abstract

This study describes an investigation of the pre-eruptive conditions (T, P and fO2) of dacite magma erupted during the KZI cycle (12,000–8400 years ago) of Kizimen Volcano, Kamchatka, the earliest, most voluminous and most explosive eruption cycle in the Kizimen record. Hydrothermal, water-saturated experiments on KZI dacite pumice coupled with titanomagnetite-ilmenite geothermometry calculations require that the KZI dacite existed at a temperature of 823 ± 20°C and pressures of 125–150 MPa immediately prior to eruption. This estimate corresponds to a lithologic contact between Miocene volcaniclastic rocks and Pliocene-Pleistocene volcanic rocks located at a depth of 5–6 km beneath the Kizimen edifice, which may have facilitated the accumulation of atypically large volumes of gas-rich dacite during the KZI cycle.