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Study on high- and ultrahigh- temperature metamorphic rocks and partial melting, with a point of view of quartz occurrence

从石英产状角度研究高温、超高温变质岩及部分熔融

基本信息

批准号：
17540432
负责人：
SHIMURA Toshiaki
金额：
$ 2.46万
依托单位：
Niigata University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2005
资助国家：
日本
起止时间：
2005 至 2007
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-17540432/
关键词：
quartz granite metamorphic rocks cathodoluminescence partial melting Hidaka Metamorphic Belt granulite zircon REE CHIME EPMA

项目摘要

Psammitic and pelitic rocks are SiO2 saturated rocks. On the partial melting process, quartz occurrence and silica saturation index are the important factors. However, modal composition of quartz is ignored as an excess component for the equilibrium computation. The purpose of this study is, analysis of timing of metamorphism, partial melting, and granitic melt separation, by the cathodoluminescence (CL) image, with a point of view of quartz occurrence.This project made innovative results. These are, we had found out older stage cores of zircon in the granulite, migmatite, tonalite, are residual material of the sediment. These must be residual grain of sediment. Whereas we also found out that bright rims is the new growth pert by the partial melting. We also revealed the age of the bright rims.Our results changed the tectonic history of the Hidaka Metamorphic Belt.These are:(1) Main thermal event is not 55Ma. That was two times, 37Ma and 19Ma.(2) 37Ma is island-arc type igneous activity.(3) 19Ma is another igneous activity related by back-arc basin opening. This stage is the MORB-type activity and the granulite facies high-temperature metamorphism.Our result was published by "Geology", and also newspapers. The CL detector was indispensable item for the new discovery.

砂质岩和泥质岩是 SiO2 饱和岩石。在部分熔融过程中，石英赋存状态和硅饱和指数是重要影响因素。然而，石英的模态成分作为平衡计算的过量成分被忽略。本研究的目的是，从石英产状的角度，通过阴极发光（CL）图像分析变质作用、部分熔融和花岗岩熔体分离的时间。该项目取得了创新成果。我们发现，这些是麻粒岩、混合岩、英云闪岩中较老阶段的锆石岩心，是沉积物的残留物质。这些一定是残留的沉积物。然而我们还发现，明亮的边缘是部分融化后新生长的。我们还揭示了明亮边缘的年龄。我们的结果改变了日高变质带的构造历史。这些是：（1）主要热事件不是55Ma。分别是37Ma和19Ma两次。(2)37Ma是岛弧型火成岩活动。(3)19Ma是另一次与弧后盆地张开有关的火成岩活动。这一阶段为MORB型活动，麻粒岩相高温变质作用。我们的研究结果发表在《地质》杂志上，也有报纸发表。化学发光探测器是这一新发现不可或缺的项目。