Studies on deformation mechanisms of regional metamorphic rocks by means of microfabric analyses

区域变质岩变形机制的微结构分析研究

基本信息

批准号：
61420015
负责人：
YOSHIDA Shizuo
金额：
$ 14.85万
依托单位：
University of Tokyo
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (A)
财政年份：
1986
资助国家：
日本
起止时间：
1986 至 1988
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-61420015/
关键词：
Metamorphic rock Slate Ophiolite Fabric Strain 変形メカニズム

项目摘要

The main purpose of this study is to know processes and mechanisms of plastic deformation of rocks by means of quantitative fabric analyses that are carried out by the x-ray texture goniometer. First, we devised and developed a computer program for measurement and data-processing through many trial experiments on micas, chlorite, hornblende, olivine, and quartz in deformed rocks. We established a highly reliable method which gives more accruate values than those from current methods, and only takes a half to one third of measuring time on a current apparatus. Results of measurement are represented quantitatively in terms of types and degrees of preferred orientation. Main results are as follows. 1. As deformation mechanisms for slates, pressure solution is dominant at a lower temperature condition, while preferred recrystallization is dominant at a higher temperature condition. The strain ellipsoids are oblate and are correlative to S fabric. 2. As deformation mechanisms for the high P/T Sambagawa metamorphic rocks, dislocation creep together with preferred recrystallization is dominant. The strain ellipsoids are generally prolate. 3. As deformational mechanism for low P/T Ryoke metamorphic rocks, diffusion creep is dominant. The strain ellipsoids are generally prolate. 4. The deformation of ultramafic tectonites, which may give a clue to know the deformational mechanism in the upper mantle, is inferred to be due to dislocation creep from the fabric pattern of olivine. In future, measurements should be carried for rocks collected from wider areas, and the relationship between amounts of strain and fabric types should be established. Comparative studies on deformation mechanisms among main orogenic belts in the world are also important to know the machanisms of plastic deformation in the deeper crust and upper mantle.

这项研究的主要目的是通过定量织物分析来了解岩石塑性变形的过程和机制，这些织物分析是由X射线纹理分子仪进行的。首先，我们通过在变形岩石中的许多试验实验进行了许多试验实验，设计和开发了一个计算机程序，用于测量和数据处理。我们建立了一种高度可靠的方法，该方法比当前方法提供的值更多，并且仅需在当前设备上测量时间的一半到三分之一。测量结果用类型和优先取向程度来定量表示。主要结果如下。 1。作为板岩的变形机制，压力溶液在较低的温度条件下是主要的，而首选的重结晶在较高的温度条件下占主导地位。应变椭圆形是植物的，并且与S织物相关。 2。作为高P/T Sambagawa变质岩石的变形机制，位错蠕变与首选重结晶在一起是主要的。应变椭圆形通常是岩体。 3。作为低p/t ryoke变质岩石的变形机制，扩散蠕变是主要的。应变椭圆形通常是岩体。 4.超镁铁质构造岩的变形可能给出了一个线索，以了解上地幔中的变形机理，这是由于橄榄石的织物模式的脱位而推断出的。将来，应对从更广泛区域收集的岩石进行测量，应建立应变量与织物类型之间的关系。关于世界上主要造山带之间的变形机制的比较研究对于了解更深的地壳和上层地幔中塑性变形的马奇主义也很重要。