权益分类	功能权益	普通用户	{{item.name}}会员
{{category.name}}	{{benefitItem.name}}

Exhumation processes of the Sambagawa metamorphic rocks, as inferred from quartz microstructures and mineral radiometric ages

从石英微观结构和矿物辐射年龄推断三巴川变质岩的折返过程

基本信息

批准号：
14340151
负责人：
TAKESHITA Toru
金额：
$ 6.21万
依托单位：
HIROSHIMA UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2002
资助国家：
日本
起止时间：
2002 至 2004
项目状态：
已结题

项目摘要

The results obtained in this research have been summarized below.(1)We have set up an automated measurement system of c-axis orientation of deformed quartz, using a Zeiss petrographic microscope, digital camera and Macintosh personal computer. This was made possible by Prof.R.Heilbronner, who stayed at Hiroshima University for 1 month in 2003, and investigated a lot of microstructures in quartz schists from the Sambagawa belt, central Shikoku with this method. The results will be submitted for a special volume of Tectonophysics.(2)The boundary and difference in the nature of terrane between the Sambagawa and Northern Chichibu belt have not been clear. In this study, we have found that the Kiyomizu Tectonic Line is the boundary fault between the two tectonic belts, which are completely different in both lithology and geologic structure.(3)We have conducted detailed geological survey and microstructural analyses of deformed quartz schist. As a result, it has become clear that an extensive folding and faulting occurred, and existing well-defined quartz c-axis fabrics were destroyed by solution-reprecipitation of quartz assisted by micro-faulting during the final exhumation stages under low temperatures in this area.(4)I hired Dr.N.Shigematsu as a research associate for three month in 2004. He was engaged in deformation experiments of K-feldspar single crystals, using a modified Griggs apparatus installed at Hiroshima University. We have found that K-feldspar single crystals deformed by mechanical twinning and intracrystalline slip, but also sometimes failed by faulting at the physical conditions (T=800゜C, strain rate=10^<-5>/s), suggesting that the experimental conditions can be correlated with those of the brittle-ductile transition. Also, these experimental conditions can be correlated with the temperature conditions of ca.400゜C at natural strain rate, which interprets that feldspars start to plastically deform around these temperatures in nature.

本研究所得结果总结如下。(1)利用蔡司岩相显微镜、数码相机和Macintosh个人电脑，建立了变形石英c轴方向自动测量系统。这是r教授的功劳。Heilbronner于2003年在广岛大学停留了1个月，用这种方法研究了四国中部三巴川带石英片岩的大量微观结构。研究结果将提交给《构造物理学》专刊。(2)三巴川带与北秩父带的界线和性质差异尚不明确。研究发现，清水构造线是两个构造带的边界断裂，这两个构造带在岩性和地质构造上都完全不同。(3)对变形石英片岩进行了详细的地质调查和微观构造分析。结果表明，在低温条件下的最后挖掘阶段，该地区发生了广泛的褶皱和断裂，原有的清晰的石英c轴结构被石英的溶解-再沉淀和微断裂破坏。2004年，我曾聘请重松博士为助理研究员，为期三个月。他使用安装在广岛大学的改良格里格斯仪器，从事钾长石单晶的变形实验。我们发现，k -长石单晶在物理条件下（T=800 C，应变速率=10^<-5>/s）会发生机械孪晶和晶内滑移，但有时也会发生断裂，这表明实验条件可能与脆性-韧性转变的条件相关。此外，这些实验条件可以与自然应变率下约400℃的温度条件相关联，这解释了长石在自然界中在这些温度附近开始塑性变形。