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首页> 外文期刊>Journal of Volcanology and Geothermal Research >Origin of Holocene trachyte lavas of the Quetrupillan volcanic complex, Chile: Examples of residual melts in a rejuvenated crystalline mush reservoir
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Origin of Holocene trachyte lavas of the Quetrupillan volcanic complex, Chile: Examples of residual melts in a rejuvenated crystalline mush reservoir

机译：智利Quetrupillan火山综合体的全新世Trachyte熔岩的起源：复兴的结晶糊状储层中残留熔体的例子

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The Quetrupillan Volcanic Complex (QVC) is a stratovolcano placed in the center of a NW-SE volcanic chain, between Villarrica volcano and Lanin volcano, in the Central Southern Volcanic Zone of the Andes. Its youngest effusive products are dominated by crystal-poor (most samples with 9 vol% phenocrysts), crystal clot-bearing trachytes (from 64.6 up to 66.2 wt% SiO2), whereas the oldest units are mainly basaltic andesites. Two-stage generation of QVC trachytes by differentiation at shallow depth (1 kbar) and NNO-QFM oxidation conditions were obtained from initial melt compositions equivalent to the Huililco basalts, a small eruptive centre located ca. 12 km NE of the QVC main vent. Pyroxene-bearing crystal clots, locally abundant in the trachytes, were formed at 900-960 degrees C (+/- 55 degrees C) and represent a dismembered crystal mush from which interstitial trachytic melts were extracted and transported upward before eruption. Heating of the crystal mush by a hotter magma recharge is inferred from complex zoned plagioclases formed at higher crystallization temperatures (50-90 degrees C) than those obtained from pyroxene. Ca-rich plagioclase overgrowths around more albitic cores, followed by an external rim of similar composition to the core are interpreted as restoration to the initial conditions of plagioclase crystallization after the mentioned heating event. Additionally, a late heating of up to 150 degrees C just prior to eruption is recorded by Fe-Ti oxide thermometry. (C) 2018 Elsevier B.V. All rights reserved.
机译：Quetrupillan火山群（QVC）是一条平流层火山，位于安第斯山脉中部南部火山区维拉里卡火山和拉宁火山之间的西北-东南火山链的中心。它最年轻的冒泡产物主要是晶体贫乏（大多数样品中<9 vol％的表晶），带有晶体凝块的丝晶（SiO2含量从64.6到66.2 wt％），而最古老的单元主要是玄武质安山岩。从浅层深度（<1 kbar）和NNO-QFM氧化条件下分化产生的两阶段QVC速溶粒是从与惠利尔科玄武岩等效的初始熔体成分中获得的，该成分位于一个约200毫米的小喷发中心。 QVC主通风口的东北角12公里。在900-960摄氏度（+/- 55摄氏度）下形成的菱形凝块，在子粒中局部富集，代表了肢解的晶体糊状物，从中抽出了间隙的子粒状熔体并向上喷出。由较热的岩浆充注加热晶体糊状物的原因是，在比从辉石获得的结晶温度更高的结晶温度（50-90摄氏度）下形成的复杂带状斜纹硅酸盐。富含Ca的斜长石在更多的岩核周围过度生长，然后与岩心组成相似的外缘被认为是在提到的加热事件之后恢复了斜长石结晶的初​​始条件。此外，在喷发之前，通过Fe-Ti氧化物测温仪记录了高达150摄氏度的后期加热。 （C）2018 Elsevier B.V.保留所有权利。

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