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首页> 外文期刊>Journal of Volcanology and Geothermal Research >Pre-eruptive physical conditions of El Reventador volcano (Ecuador) inferred from the petrology of the 2002 and 2004-05 eruptions
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Pre-eruptive physical conditions of El Reventador volcano (Ecuador) inferred from the petrology of the 2002 and 2004-05 eruptions

机译：从2002年和2004-05年喷发的岩石学推断出El Reventador火山（厄瓜多尔）的喷发前身体状况

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A petrological study of the eruptive products of El Reventador allowed us to infer the magmatic processes related to the 2002 and 2004-05 eruptions of this andesitic stratovolcano. On November 3, 2002, El Reventador experienced a highly explosive event, which was followed by emplacement of two lava flows in November-December 2002. Silica contents range from 62 to 58 wt.% SiO_2 for the November 3 pyroclastic deposits to 58-56 and 54-53 wt.% SiO_2 for the successive lava flows. In November 2004 eruptive activity resumed supplying four new lava flows (56-54 wt.% SiO_2) between November 2004 and August 2005. Volatile contents in matrix glasses and glass inclusions from the November 3 pyroclastic deposits allow us to estimate the total amount of SO_2 and HCl released into the atmosphere during the paroxysmal phase (i.e. 80 kT of SO_2 and 280 kTof HCl). Pre-eruptive pressure-temperature conditions of the magmas range from 300 to 150 MPa and ～1000 ℃ with high water contents (～ 5 wt.%). We propose the existence of an andesitic magma body located at ～7-12 km depth that is frequently intruded by more primitive, hydrous magmas from a deeper source. The initial crystallization of amphibole from the hydrous primitive magma seems typical of El Reventador, as well as the historically recurrent and regular periods of eruptive activity lasting several years. This eruptive behaviour coupled with the fractionation and mixing processes inferred from the 2002 and 2004-05 petrologic data suggest that deep magmatic recharge at El Reventador is frequent, and is probably responsible for the high frequency of eruptions.
机译：对El Reventador喷发产物的岩石学研究使我们能够推断出与该安第斯平流层火山2002年和2004-05年喷发有关的岩浆作用过程。在2002年11月3日，El Reventador经历了一次爆炸性事件，随后在2002年11月至12月放置了两个熔岩流。对于11月3日的火山碎屑沉积，二氧化硅含量为62至58 wt。％SiO_2，至58-56和连续熔岩流的54-53 wt。％SiO_2。在2004年11月，爆发活动恢复，在2004年11月至2005年8月之间提供了四种新的熔岩流（56-54 wt。％SiO_2）。11月3日热碎屑沉积物中基质玻璃和玻璃夹杂物中的挥发性成分使我们能够估算SO_2的总量盐酸在阵发性阶段释放到大气中（即80 kT的SO_2和280 kT的HCl）。岩浆的喷发前压力-温度条件范围为300至150 MPa和〜1000℃，含水量高（〜5 wt。％）。我们提出了一个位于〜7-12 km深度的安山岩体的存在，该岩体经常被来自更深层的更原始的含水岩浆侵入。闪石最初从含水的原始岩浆中结晶出来，这似乎是El Reventador的典型特征，而且历史上周期性的，周期性的爆发活动持续了数年。从2002年和2004-05年的岩石学数据推断出的这种喷发行为与分馏和混合过程相结合，表明El Reventador的深层岩浆补给很频繁，并且可能是喷发高发的原因。

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