Abstract

This paper presents new data on the age and isotope geochemistry for plateau effusive rocks sampled from the Central Kamchatka Depression and Nikolka Volcano. We have compared these materials with data on rocks sampled in the Klyuchevskaya Group of Volcanoes, as well as from Shiveluch, Kharchinsky, Zarechnyi, Nachikinsky, and Bakening volcanoes, and from an “NEB-adakite” Pliocene shield volcano in the interfluve between the Ozernaya Kamchatka and the Pravaya Kamchatka rivers. We show that the relatively “advanced,” in the sense of evolution, (mostly alkaline) compositions of rocks sampled from Nachikinsky, Bakening, and Nikolka volcanoes, as well as from the Pliocene shield edifice, have isotope characteristics that are significantly different from those for the Klyuchevskaya Group of Volcanoes. This type of rock is typical of the CKD as a rifting structure. The rocks in the Klyuchevskaya Group of Volcanoes are not typomorphic for this structure and reflect the phase of ordinary orogenic volcanism that has involved a much larger area. The Miocene plateau effusive rocks are only different from the rocks of this group in having a slightly higher potassium alkalinity. Rocks of the rifting type can be recognized, not only by their higher alkalinity, but also by a definite relationship among microcomponents: Ti/V > 0.004, Nb/Y > 0.28, Dy/Yb > 2.00, La/Yb > 6.5, Sm/Yb > 2.4, Lu/Hf < 0.08. Along with the isotope characteristics, these relationships suggest the existence of a common deep-seated asthenospheric mantle reservoir for the parent melts. The area of junction between the Kuril–Kamchatka and the Commander-Islands–Aleutian island arc system is marked by a higher fluid enrichment (the cerium REE group) in melts for rocks of some volcanoes, viz., Shiveluch, Kharchinskii, and Zarechnyi.

中文翻译：

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有关堪察加半岛中部凹陷（CKD）的年龄，物质组成和地质结构的新数据。第1部分。岩石分类。年龄，岩石学和同位素地球化学

摘要

本文介绍了从堪察加半岛中部凹陷和尼古卡火山中取样的高原喷出岩石的年龄和同位素地球化学的新数据。我们已将这些材料与在Klyuchevskaya火山群，Shiveluch，Kharchinsky，Zarechnyi，Nachikinsky和Bakening火山以及Ozernaya之间交汇处的“ NEB-adakite”上新世盾形火山中采样的岩石数据进行了比较。堪察加半岛和Pravaya堪察加半岛河流。我们显示，从演化的角度来看，从纳奇金斯基，巴肯宁和尼科尔卡火山以及上新世的盾构大厦采样的岩石（相对碱性）组成（相对碱性）具有显着不同的同位素特征的Klyuchevskaya火山群。这种岩石是裂谷构造典型的裂谷构造。火山Klyuchevskaya组中的岩石不是这种构造的错形，而是反映了涉及面积更大的普通造山带火山作用的阶段。中新世高原喷出岩与该组岩的不同之处仅在于钾碱度略高。裂谷型岩石不仅可以通过较高的碱度来识别，而且可以通过微观成分之间的明确关系来识别：Ti / V> 0.004，Nb / Y> 0.28，Dy / Yb> 2.00，La / Yb> 6.5，Sm / Yb> 2.4，Lu / Hf <0.08。这些关系连同同位素特征表明存在母体熔体的一个常见的深层软流圈地幔储层。