Time-Space of the evolution of the Hida metamorphic rocks based on CHIME age

根据锆石、独居石、铀矿和钍矿的U-Th-Pb化学年龄（CHIME年龄），研究了Hida变质带演化的时空。本研究是对Hida变质岩（Sohma et al., 1995）岩石学研究的延伸，确定了各种岩石类型的母女关系（相对年龄关系）。以下是本研究的主要结论碰撞型变质带中U-Th-Pb矿物的CHIME年龄受热液反应的控制，而不是受矿物闭合温度的控制所谓的侏罗统富那苏花岗岩体，多数为石炭系—二叠系锆石，并具有240Ma的希达变质期的独居石和铀质。它们是变质岩，将被称为Hida变质类岩Unazuki变质带并不是一个单独的变质带，而是由于Unazuki变质岩与Hida类变质岩的结合而发展成为Hida变质带的一部分飞驒变质带是一个多变质造山带，但其岩性最终形成于270ma左右Hida变质作用始于俯冲带约270Ma的花岗质岩浆活动，经历了一个热峰，随后出现了一个热液事件，其中240Ma的铀矿石结晶，并持续到变质带的隆升和冷却（角闪石和黑云母的K-Ar年龄）。

The time and space of the evolution of the Hida metamorphic belt were studied on the basis of U-Th-Pb chemical age (CHIME age) of zircon, monazite, uraninite and thorite. This study is an extention of the petrological studies of the Hida metamorphic rocks (Sohma et al., 1995), in which mother-daughter relationships (relative age relationship) of various rock types were determined. The followings are the major conclusions of this study.1 CHIME age of U-Th-Pb minerals of a collision type metamorphic belt were controled by hydrothermal reactions rather than closure temperature of the minerals.2 The majority of the so called Jurassic Funatsu granitoids show Carboniferous to Permian zircon ages in origin, and possess monazite and uraninite of the Hida metamorphic age of 240Ma. They are metamorphic rocks, and will be called the Hida metagranitoids.3 The Unazuki metamorphic belt is not a separate one, but has been developed as a part of the Hida metamorphic belt, because of the association of the Unazuki metamorphic rocks and the Hida metagranitoids.4 The Hida metamorphic belt is a polymetamorphic orogen, but its lithology were finally formed at about 270Ma.5 The Hida metamorphism started with subduction zone granitic magmatism at about 270Ma, showed a thermal peak followed by a hydrothermal event in which uraninite of 240Ma age crystallized, and continued to the uplift and cooling of the metamorphic belt as indicated by K-Ar ages of hornblende and biotite.