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首页> 外文期刊>International Journal of Earth Sciences >Early Holocene M~6 explosive eruption from Plosky volcanic massif (Kamchatka) and its tephra as a link between terrestrial and marine paleoenvironmental records
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Early Holocene M~6 explosive eruption from Plosky volcanic massif (Kamchatka) and its tephra as a link between terrestrial and marine paleoenvironmental records

机译：Plosky火山地块（Kamchatka）及其特非拉的全新世M〜6早期爆发性喷发，是陆地和海洋古环境记录之间的联系

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摘要

We report tephrochronological and geochemi-cal data on early Holocene activity from Plosky volcanic massif in the Kliuchevskoi volcanic group, Kamchatka Peninsula. Explosive activity of this volcano lasted for ～1.5 kyr, produced a series of widely dispersed tephra layers, and was followed by profuse low-viscosity lava flows. This eruptive episode started a major reorganization of the volcanic structures in the western part of the Kliuchevskoi volcanic group. An explosive eruption from Plosky (M～6), previously unstudied, produced tephra (coded PL2) of a volume of 10-12 km~3 (11-13 Gt), being one of the largest Holocene explosive eruptions in Kamchatka. Characteristic diagnostic features of the PL2 tephra are predominantly vitric sponge-shaped fragments with rare phenocrysts and microlites of plagioclase, olivine and pyroxenes, medium- to high-K basaltic andesitic bulk composition, high-K, high-Al and high-P trachyande-sitic glass composition with SiO_2 = 57.5-59.5 wt%,rnK_2O = 2.3-2.7 wt%, A1_2O_3 = 15.8-16.5 wt%, and P_2O_5 = 0.5-0.7 wt%. Other diagnostic features include a typical subduction-related pattern of incompatible elements, high concentrations of all REE (>10×mantle values), moderate enrichment in LREE (La/Yb～5.3), and non-fractionated mantle-like pattern of LILE. Geochemical fingerprinting of the PL2 tephra with the help of EMP and LA-ICP-MS analyses allowed us to map its occurrence in terrestrial sections across Kamchatka and to identify this layer in Bering Sea sediment cores at a distance of >600 km from the source. New high-precision ~(14)C dates suggest that the PL2 eruption occurred～10,200 cal BP, which makes it a valuable isochrone for early Holocene climate fluctuations and permits direct links between terrestrial and marine paleoenvironmental records. The terrestrial and marine ~(14)C dates related to the PL2 tephra have allowed us to estimate an early Holocene reservoir age for the western Bering Sea at 1,410 ± 64 ~(14)C years. Another important tephra from the early Holocene eruptive episode of Plosky volcano, coded PL1, was dated at 11,650 cal BP. This marker is the oldest geochemically characterized and dated tephra marker layer in Kamchatka to date and is anrnimportant local marker for the Younger Dryas-early Holocene transition. One more tephra from Plosky, coded PL3, can be used as a marker northeast of the source at a distance of～110 km.
机译：我们报道了从堪察加半岛的克柳切夫斯科伊火山群中的Plosky火山地块早期全新世活动的年代学和地球化学数据。该火山的爆炸活动持续了约1.5年，形成了一系列广泛分布的提夫拉层，随后是低粘度熔岩流。这次爆发事件开始了对克柳切夫斯科伊火山群西部火山结构的重大重组。以前未研究的Plosky（M〜6）爆发的火山喷发产生了10-12 km〜3（11-13 Gt）的提菲拉（编码PL2），是堪察加最大的全新世爆发性喷发之一。 PL2特非拉的特征性诊断特征主要是海绵状海绵状碎片，具有稀有的表晶和斜长石微石，橄榄石和辉石，中等至高钾的玄武质安山岩组成，高钾，高铝和高磷度的沙眼。 SiO 2 ＝ 57.5-59.5重量％，rnK_2O ＝ 2.3-2.7重量％，Al 2 O 3 ＝ 15.8-16.5重量％，P_2O_5 ＝ 0.5-0.7重量％的偏光玻璃组合物。其他诊断特征还包括典型的与俯冲有关的不相容元素模式，所有REE的高浓度（> 10×地幔值），LREE中度富集（La / Yb〜5.3）和LILE的无分形的地幔样模式。在EMP和LA-ICP-MS分析的帮助下，对PL2提夫拉的地球化学指纹图谱使我们能够绘制其在堪察加半岛陆地区域的分布图，并在距震源> 600 km的距离中识别白令海沉积物岩心中的这一层。新的高精度〜（14）C年代表明，PL2的喷发发生在〜10,200 cal BP，这使其成为全新世早期气候波动的有价值的等时线，并允许在陆地和海洋古环境记录之间建立直接联系。与PL2特非拉有关的陆地和海洋〜（14）C年代使我们能够估计白令海西部的全新世早期储层年龄为1,410±64〜（14）C年。来自Plosky火山全新世早期爆发的另一个重要特弗拉，编号为PL1，定于BP 11,650 cal。该标记物是堪察加半岛迄今为止最古老的地球化学特征和过时的特菲拉标记物层，并且是较年轻的Dryas-全新世早期过渡的重要局部标记物。来自Plosky的另一种提法拉，编码为PL3，可以用作该源东北方约110 km处的标记。

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