| Project/Area Number |
14340151
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Geology
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| Research Institution | HIROSHIMA UNIVERSITY |
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Principal Investigator |
TAKESHITA Toru Hiroshima University, Graduate School of Science, Professor, 大学院・理学研究科, 教授 (30216882)
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| Co-Investigator(Kenkyū-buntansha) |
ITAYA Tetsumaru Okayama University of Science, Research Institute of Natural Sciences, Professor, 自然科学研究所, 教授 (60148682)
ANDO Jun-ichi Hiroshima University, Graduate School of Science, Assistant, 大学院・理学研究科, 助手 (50291480)
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| Project Period (FY) |
2002 – 2004
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| Project Status |
Completed (Fiscal Year 2004)
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| Budget Amount *help |
¥9,700,000 (Direct Cost: ¥9,700,000)
Fiscal Year 2004: ¥1,800,000 (Direct Cost: ¥1,800,000)
Fiscal Year 2003: ¥1,600,000 (Direct Cost: ¥1,600,000)
Fiscal Year 2002: ¥6,300,000 (Direct Cost: ¥6,300,000)
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| Keywords | Sambagawa metamorphic rocks / exhumation processes and mechanisms / quartz c-axis fabric / Northern Chichibu belt / terrane / Normal faulting / solution-reprecipitation creep / deformation experiments of K-feldspar / 高圧型岩石変形実験装置 / ジルコン / フィッショントラック年代 / 三波川変成帯 / 構造地質学 / 変形石英の微細構造 / 微細構造画像解析 / 白雲母K-Ar年代 / 石灰岩の変形実験 / 秩父北帯 / フェンジャイト / Si値 / 石墨化度 / 変成温度圧力条件 / 高圧変成岩体 |
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| Research Abstract |
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.
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