High resolution analysis of evolution of magma chambers in island arc andesitic volcano - an example of Zao volcano past 2,000 years -

揭示岩浆房的演化是火成岩岩石学领域的主要课题之一。岩石学技术的进步使我们能够以高分辨率解决这一问题。对近期火山喷发事件的详细岩石学研究表明，岛弧火山下方的补给系统基本上由较浅的长英质和较深的镁铁质岩浆室组成。有时，喷发是由镁铁质岩浆注入较浅的洞穴而引发的。对单个或一系列喷发事件的详细研究揭示了注射导致的腔室过程的几种模式。本文研究了日本东北部枣园火山近2000年来的岩浆演化过程。这一结果对预测未来的火山喷发也很重要。

Revealing the evolution of magma chamber is one ofthe main subjects in the field of igneous petrology. Advance of petrologic technique allows us to solve this subject with a high resolution. Detailed petrologic studies on recent eruption events of volcanoes have revealed that the feeding system beneath island arc volcanoes fundamentally comprises shallower felsic and deeper mafic magma chamber. Sometimes, eruptions are triggered by the injection of mafic magmas into shallower chambers. Detailed studies of single or series of eruptive events have revealed there are several patterns of the chamber processes that result from the injections. The magma evolution course in the past ca. 2,000 years in Zao volcano, NE Japan was examined in this study. The results is also important in predicting future eruptions.