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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.

砂岩和泥质岩是SiO_2饱和岩石。在部分熔融过程中，石英产状和二氧化硅饱和指数是重要的影响因素。然而，在平衡计算中，忽略了石英的模式成分作为过剩成分。本研究的目的是从石英赋存的角度，利用阴极发光(CL)图像分析变质作用、部分熔融和花岗岩熔体分离的时间，取得了创新性的成果。这些都是，我们在麻粒岩、混合岩、英云闪长岩中发现的较老阶段的锆石核心，是沉积物的残留物。这些一定是残留的沉积物颗粒。同时，我们还发现，部分熔化后的光亮轮缘是新的生长剂。我们的研究结果改变了东高变质带的构造史，即：(1)主热事件不是55 Ma。(2)37 Ma为岛弧型火成活动。(3)19 Ma为与弧后盆地开放有关的另一次火成活动。这一阶段是MORB型活动和麻粒岩相高温变质作用。我们的研究成果发表在《地质学》上，也发表在报纸上。化学发光检测器是这一新发现不可或缺的物品。