The Amami plutonic rocks occurring in the Amami-O-shima Islands, Kagoshima Prefecture consist of six small bodies; Kasari, Ichi, Kachiura, Koniya, Ankyaba and Uke. These bodies distributed over the islands and mainly composed of adamellite and granodiorite with minor amounts of tonalite, diorite and gabbro. They are divided into peraluminous and metaluminus groups (P and M) based on their mineral assemblage, major and minor chemical compositions, K-Ar ages and Sr isotopic features. Kasari, Ichi, Koniya and Ankyaba bodies comprise the P group, and others the M group.
     The Kachiura and Uke bodies of the M group gave K-Ar ages of 17.23±0.22 Ma and 110.3±1.2 Ma, respectively. Age from the Kachiura body is similar to that of granitoids in outer zone of southwest Japan (OZSWJ) rather than that of the P group. Mineralogical and geochemical characteristics and the initial Sr ratio of the Kachiura body are similar to those of I-type granitoids of OZSWJ.
     Muscovite contents and A/CNK ratios in the P group increase continuously from the back arc side to the trench side, and their initial Sr ratios also show the same trend except for the Ankyaba body. The original magmas on the trench side were more affected by pelite-rich continental materials than those on the back arc side. Such spatial variation is also recognized in granitoids of OZSWJ.
     The Amami plutonic rocks have similar chemical and petrological characteristics to granitoids of OZSWJ, however, ages of the plutonic rocks are different. Common petrological characteristics between both rocks may have resulted from similar tectonic condition.

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The Tanzawa group is composed of Miocene andesitic-basaltic volcanic and volcaniclastic rocks in the southern Tanzawa Mountains, central Japan. It can be divided into the stilbite, laumontite, prehnite-pumpellyite, epidote, epidote-amphibole and amphibole zones. The occurrence and chemistry of Ca-Al silicates are described. The Fe³⁺ contents of prehnite, pumpellyite and epidote decrease with increasing metamorphic grade. But in one sample or one metamorphic zone, the Fe³⁺ contents of pumpellyite, prehnite and epidote mainly change with coexisting minerals. Widespread hematite±titanite, grandite garnet and abundant Fe³⁺-rich Ca-Al-Fe³⁺ silicates indicate high fo₂ of fluid during metamorphism of the Tanzawa group. The high fo₂ of fluid controls paragenetic changes between prehnite-pumpellyite and greenschist facies and results in wide distribution of epidote zone and absence of amphibole+prehnite+epidote and amphibole+pumpellyite+epidote assemblages.

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A flow through type experimental reaction system was developed to simulate water-rock interaction in the upper crust conditions. The newly designed apparatus enables flow through experiments to be conducted under conventional triaxial compression condition at high temperature and have the ability to measure shrinkage, and permeability while the experiment is in progress. Specification is as follows : temperature to 300°C, fluid pressure up to 40 MPa, axial loads up to 25ton (250 MPa), and flow rates from 0 ml/min to 10 ml/min (flow velocities about from 0 cm/min to 1 cm/mm).
     The investigation of the compaction of andesite powder (63 to 90 μm) with deionized water flow was performed using above apparatus at 300°C, fluid pressure 10 MPa, effective axial load pressure to sample 30 MPa, flow rate 1.5 ml/min for 10 days. The main elements in the reacted solution was Si, Na, and K, but Fe, Al, Ca, and Mg remained in the solid. The alteration products such as smectite was observed on grain surface. The permeability was almost the constant value during progress of the shrinkage, and the bulk density was decreased by leaching. These facts suggest that new flow pass was formed in the andesite sample under triaxial compression condition.

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