Physicochemical parameters of crystallization of melts in intermediate suprasubduction chambers (by the example of Tolbachik and Ichinskii Volcanoes, Kamchatka Peninsula)

详细信息    查看全文

• 作者：N.L. Dobretsov^a ; ^c ; V.A. Simonov^b ; ^c ; A.V. Kotlyarov^b ; ^{kotlyarov@igm.nsc.ru" class="auth_mail" title="E-mail the corresponding author} ; R.Yu. Kulakov^c ; N.S. Karmanov^b
• 关键词：physicochemical parameters of crystallization ; intermediate suprasubduction chambers ; melt inclusions ; basalt and andesite minerals ; Kamchatka volcanoes
• 刊名：Russian Geology and Geophysics
• 出版年：2016
• 出版时间：July 2016
• 年：2016
• 卷：57
• 期：7
• 页码：993-1015
• 全文大小：3979 K

文摘

In study of plagioclases, amphiboles, and melt inclusions, we have determined the physicochemical parameters of crystallization of melts in the intermediate suprasubduction chambers of volcanoes representing different types of subduction magmatism on the Kamchatka Peninsula: the young basaltic systems of Tolbachik Volcano (Klyuchevskaya group) and ancient Ichinskii Volcano (Sredinnyi Ridge) with alternating basaltic and felsic eruptions. For Tolbachik Volcano, we have found that plagioclase lapilli formed from basaltic melts at 1075-1115 °C and low (< 1 kbar) pressures at depths of 2-3 km. Andesite minerals crystallized within a wider range of temperatures and pressures (1220-1020 °C and 3.3-1.6 kbar) in an intermediate chamber at depths of < 10 km. The melts were generated in basaltic magma chambers (detected well by geophysical methods at depths of 18-20 km) with minimum temperatures of ~ 1290 °C. For Ichinskii Volcano, three levels of intermediate chambers are distinguished. Andesites formed at depths of < 23 km at < 1225 °C. Dacitic melts were generated from an intermediate chamber (14 km) at 1135-1045 °C as a result of differentiation of andesitic magmas. Dacites formed in the uppermost horizons (9-3 km) at 1130-1030 °C. Despite the similarity between differentiation processes in the intermediate chambers of the Kamchatka volcanoes, each volcano is characterized by specific magmatism. The lavas of basaltic volcanoes (Tolbachik) and those of andesitic volcanoes (Ichinskii) differ in genesis and differentiation.