Abstract Avachinsky, Kozelsky, and Koryaksky volcanoes form one of the most volcanically active clusters in the Kamchatka volcanic arc and are located in close proximity of the cities of Petropavlovsk-Kamchatsky and Elizovo – the most populated area in Kamchatka. In this paper, we report a compilation of new and revised previously published data on the eruptive history of these volcanoes during the past 13.5 kyrs. We identify 217 explosive eruptions of these volcanoes, determine their ages using 207 radiocarbon dates and Bayesian statistical modeling, and characterize their tephra geochemically using major and trace element compositions of bulk samples (40 samples) and volcanic glass (75 samples). Avachinsky has been the most active during the Holocene time and had >150 explosive eruptions; Koryaksky produced ~60 eruptions; and Kozelsky had only two final eruptions in the early Holocene. Our new data confirm the onset of the Avachinsky postglacial activity at 11.3 cal ka BP and previously distinguished two major stages of Avachinsky Holocene eruptive history: stage I (8–3.8 cal ka BP) and stage II (3.8 cal ka BP – present). During stage I, eruptions were relatively rare, but they included at least six large pumice eruptions with tephra volumes exceeding 0.5 km3. Stage I tephras had low-K andesitic bulk compositions and low-K rhyolitic matrix glasses. The andesites likely sampled volatile-rich crystal mush from a long-lived magma chamber under Avachinsky volcano. The stage II started at ~3.8 cal ka BP with a powerful eruption and was related to the construction of the Young Cone inside the Avachinsky somma. The subsequent late Holocene eruptions were frequent, but most of them did not exceed the volume of 0.3 km3. The stage II tephras are mostly cindery basaltic andesites containing well-crystallized groundmasses of andesitic composition. These tephras originate from smaller, perhaps more shallow magmatic reservoirs, and their matrix glasses are likely products of in-situ crystallization of relatively mafic magmas on their ascent to the surface. Koryaksky volcano was mostly active in the early Holocene when Avachinsky was quiet. Koryaksky tephras had a relatively constant bulk medium-K andesitic composition during the Holocene. Thanks to characteristic compositions, high frequency, and well-constrained ages, tephras of Avachinsky and Koryaksky volcanoes can be used for high resolution dating of local sediments. Some eruptions of Avachinsky volcano reached volcanic explosivity index (VEI) 5 and produced widely dispersed tephras. These eruptions could have had global environmental effects, and their tephras can be used for the correlation of disparate sedimentary archives. Some Avachinsky and Koryaksky eruptions were closely spaced in time. However, their tephras are easily distinguished by respective low-K and medium-K compositions and by different trace element patterns, which imply compositionally different sources in the mantle wedge. We interpret these differences to reflect the increasing slab surface temperature and transition of slab component from a relatively low-temperature fluid-like phase under Avachinsky to more high-temperature and solute-rich supercritical fluid or melt under Koryaksky. The transition appears to be very sharp in Kamchatka, causing a large compositional shift in magmas just behind the volcanic front.

中文翻译：

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堪察加半岛 Avachinsky、Kozelsky 和 ​​Koryaksky 火山的全新世主要火山喷发详细的年代学和组成

摘要 Avachinsky、Kozelsky 和 ​​Koryaksky 火山是堪察加火山弧中火山活动最活跃的火山群之一，位于堪察加地区彼得罗巴甫洛夫斯克和埃利佐沃市附近。在本文中，我们报告了过去 13.5 kyrs 期间这些火山喷发历史的新的和修订的先前发布的数据的汇编。我们确定了这些火山的 217 次爆发性喷发，使用 207 个放射性碳日期和贝叶斯统计模型确定了它们的年龄，并使用散装样品（40 个样品）和火山玻璃（75 个样品）的主要和微量元素组成对它们的火山灰进行了地球化学特征。阿瓦钦斯基在全新世时期最为活跃，有超过 150 次的爆发性喷发；Koryaksky 产生了约 60 次喷发；和科泽尔斯基在全新世早期只有两次最后的喷发。我们的新数据证实了 Avachinsky 冰后活动在 11.3 cal ka BP 开始，并且之前区分了 Avachinsky 全新世喷发历史的两个主要阶段：I 阶段（8-3.8 cal ka BP）和 II 阶段（3.8 cal ka BP – 现在）。在第一阶段，喷发相对较少，但至少包括 6 次火山灰体积超过 0.5 平方公里的大型浮石喷发。阶段 I tephras 具有低 K 安山岩整体成分和低 K 流纹岩基质玻璃。安山岩可能从阿瓦钦斯基火山下的一个长寿命岩浆房中采集了富含挥发物的晶体糊状物。第二阶段开始于约 3.8 cal ka BP，伴随着一次强大的喷发，并且与 Avachinsky somma 内年轻锥体的构造有关。随后的全新世晚期火山喷发频繁，但大部分都没有超过 0.3 立方千米的体积。第二阶段的火山灰主要是火山灰玄武质安山岩，含有结晶良好的安山岩基质。这些火山灰起源于更小、可能更浅的岩浆储层，它们的基质玻璃很可能是相对基性岩浆上升到地表时原位结晶的产物。科里亚克火山主要活跃于全新世早期，当时阿瓦钦斯基处于平静状态。在全新世期间，Koryaksky tephras 具有相对恒定的大块中钾安山岩成分。由于特征成分、高频和严格的年龄限制，Avachinsky 和 ​​Koryaksky 火山的 tephras 可用于对当地沉积物进行高分辨率测年。Avachinsky 火山的一些喷发达到了火山爆发指数 (VEI) 5 并产生了广泛分散的火山灰。这些火山喷发可能对全球环境产生影响，它们的火山灰可用于不同沉积档案的关联。一些 Avachinsky 和 ​​Koryaksky 喷发的时间间隔很近。然而，它们的火山灰很容易通过各自的低 K 和中 K 成分以及不同的微量元素模式来区分，这意味着地幔楔中成分的不同来源。我们解释这些差异以反映板坯表面温度的升高和板坯组分从 Avachinsky 下相对低温的类流体相转变为 Koryaksky 下更高温和富含溶质的超临界流体或熔体。堪察加半岛的转变似乎非常明显，