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首页> 外文期刊>Journal of Volcanology and Geothermal Research >Geochemistry and evolution of the Santiaguito volcanic dome complex, Guatemala
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Geochemistry and evolution of the Santiaguito volcanic dome complex, Guatemala

机译：危地马拉Santiaguito火山穹顶综合体的地球化学和演化

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摘要

One of the longest continuous periods of dome-forming activity on record is the ongoing eruption of Santiaguito, Guatemala. Dome-building began in 1922, within the crater formed during the cataclysmic 1902 eruption of Santa Maria, and continues today. The earliest erupted Santiaguito lavas are chemically and mineralogically identical to the dacite pumice erupted in 1902. The erupted magma has become progressively less evolved over time, with a decrease in whole rock SiO_2 from ～66 to ～62 wt.% from 1922 to 2002. New geochemical data from Santiaguito are consistent with a model of magma being extracted progressively from a chemically-stratified lower crustal (～12 to ～25 km) storage zone thought to have formed during the ～25 ka of quiescence that preceded the 1902 eruption. The bimodal distribution of plagioclase phenocryst core compositions in early Santiaguito lavas suggests that they were strongly influenced by magma mixing in addition to fractional crystallization. However, lavas erupted since the 1940s show a unimodal distribution, suggesting a diminishing role for mixing within the Santiaguito system. Trace element data suggest that the decrease in silica content over time is best explained by a decrease in the extent of fractional crystallization of～15% over the 80 years covered by our sample set.
机译：形成圆顶活动的最长连续时期之一是危地马拉桑蒂亚吉托的持续喷发。圆顶建筑始于1922年，当时是在1902年圣玛丽亚灾难性喷发期间形成的火山口内，一直持续到今天。最早喷出的桑蒂亚吉托火山熔岩在化学和矿物学上与1902年喷出的辉绿岩浮石相同。随着时间的流逝，喷出的岩浆逐渐变少，从1922年到2002年，整个岩石中的SiO_2含量从〜66重量％降低到〜62重量％。来自Santiaguito的新地球化学数据与从化学分层的下地壳（〜12至〜25 km）存储区中逐渐提取的岩浆模型相一致，认为该存储区是在1902年喷发之前约25 ka的静止期形成的。早Santiaguito熔岩中斜长石面隐晶岩核心成分的双峰分布表明，除了部分结晶外，它们还受到岩浆混合的强烈影响。但是，自1940年代以来喷发的熔岩呈单峰分布，表明在Santiaguito系统中混合作用减弱。痕量元素数据表明，随着时间的流逝，二氧化硅含量的下降可以用我们的样本集涵盖的80年间的部分结晶程度降低约15％来最好地解释。

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