Role and chemical characteristics of magmatic fluid on material recycling process between earth's crust and upper mantle at subduction zone.

具有代表性的低碱拉斑岩样品采集于火山锋的岩手火山、南灶火山和Adatara火山以及日本东北弧火山锋内侧的秋田- komagatake火山。本研究的基本概念是，必须从单个火山岩浆源地幔的非均质性中推断出板源流体的特征。这种地幔非均质性需要通过石油化学研究来揭示，以明确母岩浆的多样性和被认为起源于地幔的拉斑岩浆批次系统的演化过程。岩手火山共发现5个拉斑岩岩浆批次，每个批次都有不同的母岩浆和演化过程。南灶火山的拉斑岩系列也有3套同生岩浆。而秋田- komagatake火山在其破火山口后阶段至少存在4套拉斑岩浆。单火山内的拉斑母岩浆具有明显的化学特征，认为火山锋下岩浆源区可能通过板源流体的matas成岩作用富集Rb和K，而不富集Ba。此外，火山前缘共存的拉斑岩岩浆套件和钙碱性岩浆套件的LIL/HFS差异可能反映了岩浆源区的非均质性。此外，还揭示了分馏结晶并不总是拉斑岩系列的主要演化过程；岩浆混合或同化作用可能是主要作用

Representative low-alkali tholeiitic rock samples are collected from Iwate, Minami-Zao and Adatara volcanoes at volcanic front and also from Akita-Komagatake at inner side from the volcanic front in northeastern Japan arc. Basic concept of this research is that the characteristics of slab-derived fluid must be inferred from the heterogeneity postulated in magma source mantle beneath a single volcano. Such mantle heterogeneity should be revealed through petrochemical investigations trying to make clear the diversity of parental magmas and evorutionary processes for the tholeiitic magma batch systems that is believed to originate in mantle.Five tholeiitic magma batch systems are recognized at Iwate volcano, and each batch has distind parental magma and evolutionary process. Similarly, 3 co-genetic magma suites are distinguished among the tholeiitic series at Minami-Zao volcano. As for the Akita-Komagatake volcano, at least 4 suites of tholeiitic magmas exist in its post-caldera stage.Based on distinctive chemical characteristics among the tholeiitic parental magmas within a single volcano, the magma source region beneath the volcanic front may be enriched in Rb and K but not Ba through matasomatism by slab-derived fluid. Further, difference in LIL/HFS between tholeiitic and calc-alkaline magma suites coexisting at the volcanic front may reflect such heterogeneity in magma source region. In addition, it is revealed that the fractional crystallization is not always the main evorutionary process in the tholeiitic series ; magmatic mixing or assimialation may be the main