Geochronology of paleo-earthquake -dating of fault materials by earthquake-

古地震地质年代学 - 通过地震对断层物质进行测年 -

基本信息

批准号：
11440151
负责人：
ITAYA Tetsumaru
金额：
$ 6.14万
依托单位：
Okayama University of Science
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B).
财政年份：
1999
资助国家：
日本
起止时间：
1999 至 2000
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-11440151/
关键词：
earthquake fault materials fault gouge mica-clay minerals K-Ar method Ar-Ar method TL method ESR method 年代測定放射線損傷法断層シュードタキライト

项目摘要

This is to date the materials formed during fault movement accomapnied with paleo-earthquakes by K-Ar, Ar-Ar and radiation damage methods after the identification of fault rocks formed by earthquakes.In order to estimate natural radiation level in TL and ESR dating, a portable γ-ray meter was purchased. We also constructed the automated laser step heating system for Ar-Ar dating of single mineral grain.Many structural geologists supported us for sampling of fault rocks, mainly pseudotachlytes from Oshima of Ehime Prefecture and fault gouges from Atotsugawa, Hatagawa, Tasuke and Tanakura systems in Japan, and from MCT in Nepal and Yangsan fault in Korea.Oshima pseudotachlytes and their host metamorphic rocks were dated with the Ar/Ar spot daing method using a pulsed laser. The later results give 100-110Ma for amphiboles and the former, 60-80Ma. The ages of gouges are about 3Ma for the Nepal MCT, 40-50Ma for the Tanakura, 38-46Ma for the Yangson. In the Atotsu system, the ages become younger with decreasing grain size of separates from granites. This tendency is not observed in the separates from sedimentary rocks. However, the ages are about 60Ma.We examined the discordant age relations due to K ion trapped in the expanded layers of smectite When K ion is exchanged by NH4 ion, the ages get 2-5% older than those of the original smectite.We have published more than 20 papers on the results of this project and the related subjects.

这是在鉴定地震形成的断层岩石后，用K-Ar、Ar-Ar和辐射损伤方法对伴随古地震的断层运动形成的物质进行测定。为了估算TL和ESR测年中的自然辐射水平，我们还购买了便携式γ射线仪，建立了自动激光步进加热系统，用于单矿物颗粒的Ar-Ar测年。许多构造地质学家支持我们对断层岩进行取样，主要是来自爱媛县大岛的假速水石。来自日本阿十津川、畑川、田助和田仓系统以及尼泊尔 MCT 和韩国梁山断层的县和断层泥。后来使用脉冲激光采用 Ar/Ar 斑点法测定了大岛假太赫岩及其寄主变质岩的年代。结果显示，角闪石为 100-110Ma，前者为 60-80Ma。尼泊尔的凿岩年龄约为 3Ma。 MCT，Tanakura 为 40-50Ma，Yangson 为 38-46Ma。在 Atotsu 系统中，随着花岗岩分离物粒度的减小，年龄变得更年轻，但在沉积岩分离物中却没有观察到这种趋势。约为60Ma。我们检查了由于K离子被困在蒙脱石的膨胀层中而导致的不一致的年龄关系当K离子与NH4离子交换时，年龄得到比原来的蒙脱石老2-5%。我们已就该项目及相关课题的成果发表了20多篇论文。