2024/10/18 更新

写真a

カメダ ジュン
亀田 純
Kameda Jun
所属
惑星物質研究所 教授
職名
教授
外部リンク

学位

  • 博士(理学) ( 2004年6月   東京大学 )

研究キーワード

  • 付加体

  • 粘土鉱物

  • 続成作用

研究分野

  • 自然科学一般 / 固体地球科学

学歴

  • 東京大学   Graduate School of Science  

    2000年4月 - 2004年6月

      詳細を見る

  • 東京大学   Graduate School of Science  

    1998年4月 - 2000年3月

      詳細を見る

  • 東京大学    

    1994年4月 - 1998年3月

      詳細を見る

経歴

  • 岡山大学   惑星物質研究所   教授

    2024年1月 - 現在

      詳細を見る

  • 北海道大学   大学院理学研究院   准教授

    2015年4月 - 2023年12月

      詳細を見る

  • 北海道大学   大学院理学研究院   講師

    2013年10月 - 2015年3月

      詳細を見る

  • 東京大学   大学院理学系研究科   特任助教

    2009年4月 - 2013年9月

      詳細を見る

所属学協会

委員歴

  • 北海道防災会議地震火山対策部会地震専門委員  

    2022年9月 - 2024年3月   

      詳細を見る

  • 幌延深地層研究確認会議 専門委員  

    2022年4月 - 2024年3月   

      詳細を見る

  • 日本地質学会   理事  

    2018年6月 - 2024年5月   

      詳細を見る

    団体区分:学協会

    researchmap

  • 日本地質学会北海道支部   幹事庶務  

    2016年4月 - 2020年3月   

      詳細を見る

    団体区分:学協会

    researchmap

 

論文

  • Thermogenic methane and hydrogen generation in subducted sediments of the Nankai Trough 査読

    Noriyuki Suzuki, Koutaro Koike, Jun Kameda, Gaku Kimura

    Communications Earth & Environment   2024年2月

     詳細を見る

    掲載種別:研究論文(学術雑誌)  

    DOI: 10.1038/s43247-024-01252-7

    researchmap

  • Lowering of the kinetic barrier of clay-mineral reactions along a seismogenic fault: Example from the Nankai subduction zone, Japan 査読

    Hirokazu Masumoto, Jun Kameda, Yohei Hamada, Kohtaro Ujiie, Yujin Kitamura

    Tectonophysics   868   2023年12月

     詳細を見る

    掲載種別:研究論文(学術雑誌)  

    An analysis of clay minerals in core samples around the megasplay fault of the Nankai Trough, Japan, recovered during the Integrated Ocean Drilling Program Nankai Trough Seismogenic Zone Experiment reveals a local progression of the smectite-to-illite conversion (S–I) reaction in the slip zone, possibly associated with local thermogenesis caused by seismic slip on the fault. Our semiquantitative X-ray diffraction analysis demonstrates that the illite content in mixed-layer illite/smectite is ∼15% higher in the gouge than in the host sediments. The thermal history of the fault, constrained in a previous study, requires a reduction of the apparent activation energy by 20–30% compared with the literature value to explain the observed illitization. The Shirako Fault in the Miura–Boso accretionary complex, which is thought to have been activated in a tectonic setting similar to that of the megasplay fault of the Nankai Trough, also shows a 20–30% reduction in the apparent activation energy. These results suggest that the kinetic barrier of the smectite–illite reaction is lowered as a result of mechanochemical processes in seismogenic fault zones.

    DOI: 10.1016/j.tecto.2023.230083

    Scopus

    researchmap

  • Surface Physicochemical Properties of Smectite-Rich Fault Gouge: A Case Study of the Japan Trench Plate-Boundary Fault 査読

    Keisuke Nakamoto, Motoki Kamei, Jun Kameda

    Geophysical Research Letters   50 ( 11 )   2023年6月

     詳細を見る

    掲載種別:研究論文(学術雑誌)  

    The frontal part of the Japan Trench plate-boundary fault is enriched in low-strength smectite, and this material characteristic is thought to be a factor for the large fault slip during the 2011 Mw 9.0 Tohoku-oki earthquake. In this study, we evaluated the surface physicochemical properties of the particles that constitute the fault zone and examined their effect on the rheological properties of the fault. Measurements of the zeta potential, surface free energy and pore size distribution indicate that the interparticle interaction in the in situ state is very weak. This means that the viscous resistance is low, which may have contributed to the large fault slip during the earthquake. The interparticle distance appears be longer than the energetically stable state, which may reflect a transitory state after the earthquake. Changes in microscopic interparticle interactions during coseismic and interseismic periods may influence the rheological behaviors of the Japan Trench plate-boundary fault.

    DOI: 10.1029/2023GL104271

    Scopus

    researchmap

  • Rheological properties of concentrated allophane, halloysite, and kaolinite suspensions 査読

    Jun Kameda, Tomonori Morisaki

    APPLIED CLAY SCIENCE   226   2022年9月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ELSEVIER  

    This study investigated the rheological properties of concentrated suspensions of allophane, halloysite, and kaolinite, which are representative of a series of weathering products of volcanic glass and feldspar minerals in volcanic rocks and deposits, to elucidate the mechanism of landslide generation involving these materials. All suspensions generally showed shear thinning during flow curve measurements, as represented by a steady decrease of viscosity with increasing shear strain rate from 0.1 to 1000 s-1. A difference among them was that the kaolinite suspension showed unstable flow behavior at high solid concentration, and the halloysite suspension had a similar behavior at low solid concentration. The shear stress at the beginning of flow-which represents the yield stress of the suspension-showed a power law correlation with the solid volumetric fraction, and that for kaolinite agreed well with previous static yield stress measurements. The stress of the halloysite suspension deviated from the power law curve at solid fraction < -0.15. Dynamic viscoelasticity tests indicated that all suspensions showed a power law correlation between the modulus value and solid fraction. The crossover strain (when a solidlike-to-liquidlike transition occurs) of the kaolinite suspension was almost constant within the investigated solid fraction range, whereas that of the halloysite suspension decreased noticeably at solid fraction < -0.15. Overall, the allophane suspension had the weakest strength and lowest resistance to oscillatory strain at a given solid fraction condition. The rheological properties of halloysite observed here may be related to the occurrence of flow-like, long-distance landslides in volcanic areas containing weathered tephra.

    DOI: 10.1016/j.clay.2022.106557

    Web of Science

    researchmap

  • Rheological properties of halloysite soil slurry: a case study of weathered tephra involved in a shallow landslide triggered by the 2018 Eastern Iburi earthquake in Hokkaido, Japan 査読

    Jun Kameda

    EARTH PLANETS AND SPACE   74 ( 1 )   2022年5月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:SPRINGER  

    The 6.7 M-w Eastern Iburi earthquake of 6 September 2018 triggered destructive landslides in southern Hokkaido, Japan, many of which were characterized by the flow-like downslope movement of volcanic soils formed from weathered tephra containing halloysite. This study aims to elucidate the mechanism of landslide generation through rheological characterization of halloysite soil slurries. The examined slurries were prepared from either oven-dried or moist soil. Both slurries showed a power-law correlation between measured yield stress and moisture content. However, at a given water content, slurry made from dried soil showed stresses that are one-to-two orders of magnitude lower than those of slurry made from moist soil. Compared with the measurements for the slurry of dried soil, those for the slurry of moist soil are closer to prior numerical modeling of a specific landslide, indicating that the soils involved were moist. The yield stress also varied with slurry pH, generally increasing with decreasing pH, which is in part explained by the DLVO force model based on the electrical double layer and van der Waals forces between the colloidal particles. The pH dependence is more prominent in the slurry of moist soil, and thus the mechanical state of the slope appears to vary significantly with rainfall-induced changes in subsurface chemistry. Dynamic viscoelasticity measurement indicated that both initially solid-like slurries can become fluid under an applied oscillatory strain of 0.5 to 10 Hz: the susceptibility to fluidization depends greatly on water content and frequency. The ground motion during the earthquake easily fluidized the slurry, indicating this was a factor contributing to the observed flow-like landslides.

    DOI: 10.1186/s40623-022-01623-4

    Web of Science

    researchmap

  • Stick-slip behavior of a clayey crustal fault 査読

    Jun Kameda, Yohei Hamada

    PHYSICAL REVIEW RESEARCH   4 ( 1 )   2022年3月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:AMER PHYSICAL SOC  

    Recent studies have revealed that slip on clay-rich fault planes, which develop in the shallow crust and can cause huge earthquakes, is controlled by their flow properties rather than their frictional properties. Here, we simulate a seismogenic crustal fault and show that such a fault plane may behave as a thixotropic yield stress fluid. We then conduct numerical experiments using a simple spring-slider model that incorporates this thixotropic property, and we successfully reproduce spontaneous stick-slip behaviors that correspond to a variety of seismogenic processes, ranging from regular earthquakes with high slip rates to slow earthquakes with lower slip rates. This finding suggests that the seismic activity on a shallow clay-rich crustal fault may be governed by the time-evolving microstructure of the clay-water system that exists along the fault plane.

    DOI: 10.1103/PhysRevResearch.4.013211

    Web of Science

    researchmap

  • 窒素ガス吸着法を用いた沈み込み帯断層の微小間隙構造分析

    中元 啓輔, 亀田 純, 濱田 洋平, 増本 広和

    日本地質学会学術大会講演要旨   2022   290   2022年

     詳細を見る

    記述言語:日本語   出版者・発行元:一般社団法人 日本地質学会  

    沈み込み帯における断層運動は津波を伴う地震を発生させる可能性があり,地震性すべりのメカニズム解明はきわめて重要である.地震性すべりを引き起こす断層運動は間隙水圧の上昇などの流体による影響が考えられる (Sibson, 1973).流体の挙動は透水性によって支配されており,透水性は間隙率との相関性がみられる.しかし,透水性は間隙率だけではなく,間隙構造の違いによっても変化すると考えられる.断層岩の間隙率推定は水銀圧入法や海洋掘削においてはMAD法などによって行われているが,本研究では間隙構造推定に窒素ガス吸着法を用いる.窒素ガス吸着法の岩石への適用はシェールガスなどの資源探査分野で行われており,頁岩のガス貯蔵量推定に用いられている.この手法は水銀圧入法よりも小さい細孔の分析に適しており,細孔容積,BET比表面積といったナノスケールでの岩石の構造を表すパラメータの解析が可能となる.本発表では断層岩の微小構造分析における窒素ガス吸着法の有用性について検討する.

    今回用いた断層岩試料はIODP Exp. 316 (NanTroSEIZE),IODP Exp. 343(JFAST),延岡衝上断層掘削プロジェクト(NOBELL)で採取されたボーリングコア試料と房総半島の白子断層である.試料は実験前に425μm以下に粉砕し,200℃で12時間真空脱気し試料表面の吸着分子を取り除いた.前処理した試料を窒素ガス吸着法で測定し吸脱着等温線 (isotherm)を得た.得られた吸脱着等温線からBET法によりBET比表面積,BJH法により細孔径分布を求めた.

    測定した吸脱着等温線はすべての試料でヒステリシスがみられた.ヒステリシスの形状は細孔の形状を反映すると考えられており(Sing, 1985),測定した試料内で産地・鉱物組成ごとの差だけではなく,断層と原岩の間にもその形状の違いがみられ,断層運動による細孔構造の変化が示唆された.

    BET比表面積を比較すると,間隙率の高い浅部の断層では比較的高い値を示しているが,深部の断層では明確に低下している.また,白子断層のBET比表面積は断層において急激に増加している傾向がみられ,表面構造の変化においても断層運動の影響が示唆された.



    引用文献

    Sibson, R. H. (1973). Interactions between temperature and pore-fluid pressure during earthquake faulting and a mechanism for partial or total stress relief. Nature Physical Science, 243(126), 66-68.

    Sing, K. S. (1985). Reporting physisorption data for gas/solid systems with special reference to the determination of surface area and porosity (Recommendations 1984). Pure and applied chemistry, 57(4), 603-619.

    DOI: 10.14863/geosocabst.2022.0_290

    researchmap

  • 3D fault-zone architecture across the brittle-plastic transition along the Median Tectonic Line, SW Japan: Fault-rock characterization 査読

    Takuma Katori, Norio Shigematsu, Jun Kameda, Ayumu Miyakawa, Risa Matsumura

    JOURNAL OF STRUCTURAL GEOLOGY   153   2021年12月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:PERGAMON-ELSEVIER SCIENCE LTD  

    We determine the features and distribution of fault rocks along the Median Tectonic Line (MTL), SW Japan, to establish the 3D architecture of the fault zone across the brittle-plastic transition. Cataclasites exposed close to the lithological boundary fault (the MTL) can be divided into those formed by sinistral faulting at temperatures of -300 degrees C and those formed by dextral faulting at -250 degrees C. Mylonites distributed to the north of the cataclasites were formed by sinistral faulting and can be divided into lower-temperature mylonite (L-T mylonite) close to the MTL and higher-temperature mylonite (H-T mylonite) distant from the MTL, where deformation temperatures were lower and higher than 400 degrees C, respectively. Structures formed by sinistral faulting are oblique to those formed by dextral faulting, indicating that the former structures are older than the latter. Structures formed by sinistral faulting underwent deformation around the brittle-plastic transition. Thus, the MTL fault zone records deformation through a crustal section. Microstructural observations suggest that the differential stress just below the brittle-plastic transition (L-T mylonite) was -200 MPa and that this value may not change substantially in the deep crust (H-T mylonite).

    DOI: 10.1016/j.jsg.2021.104446

    Web of Science

    researchmap

  • Generation of oxidising fluids by comminution of fault rocks 査読

    Jun Kameda, Atsushi Okamoto

    Geochemical Perspectives Letters   19   32 - 35   2021年10月

     詳細を見る

    掲載種別:研究論文(学術雑誌)   出版者・発行元:European Association of Geochemistry  

    DOI: 10.7185/geochemlet.2131

    researchmap

  • Mineralogical and physico-chemical properties of halloysite-bearing slip surface material from a landslide during the 2018 Eastern Iburi earthquake, Hokkaido

    Jun Kameda

    Progress in Earth and Planetary Science   8 ( 1 )   2021年6月

     詳細を見る

    掲載種別:研究論文(学術雑誌)  

    Destructive landslides were triggered by the 6.7 Mw Eastern Iburi earthquake that struck southern Hokkaido, Japan, on 6 September 2018. Heavy rainfall on 4 September in addition to intermittent rainfall around the Iburi Tobu area saturated and weakened the slope-forming materials (mostly altered volcanoclastic soils), making them susceptible to failure because of the earthquake’s strong ground motion. Most of the shallow landslides exhibited long runouts along gentle hill slopes, with characteristic halloysite-bearing slip surface at the base of the volcanic soils. This study investigated the mineralogical and physico-chemical properties of the slip surface material with the aim of understanding weakening and post-failure behaviors during the landslides. Halloysite in the slip surface had irregular-to-hollow-spherical morphology with higher mesopore volumes than tubular halloysite, which is related to a high capacity for water retention after rainfall. To reproduce possible chemical changes in the slip surface during rainfall, the sample was immersed in varying amounts of rainwater; solution pH increased and ionic strength decreased with increasing water content. These findings, alongside electrophoretic analysis, suggest that rainwater infiltration could have increased the absolute zeta potential value of the slip surface material. It is suggested that rainfall before the earthquake enhanced the colloidal stability of halloysite particles within the slip surface, owing to an increase in electrostatic repulsion. This decreased the material’s cohesive strength, which might have led to destabilization of the slope during ground shaking generated by the earthquake, and subsequent high-mobility flow after failure. [Figure not available: see fulltext.].

    DOI: 10.1186/s40645-021-00428-5

    Scopus

    researchmap

  • 1-D inversion analysis of a shallow landslide triggered by the 2018 Eastern Iburi earthquake in Hokkaido, Japan

    Jun Kameda, Atsushi Okamoto

    EARTH PLANETS AND SPACE   73 ( 1 )   2021年5月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:SPRINGER  

    Destructive landslides were triggered by the 6.7 M-w Eastern Iburi earthquake that struck southern Hokkaido, Japan, on 6 September 2018. In this study, we carried out 1-D inversion analysis of one of the shallow landslides near the epicenter using a Bing debris-flow model. At this site, the slope failure comprised cover soil with an initial down-slope length of similar to 80 m and a thickness of similar to 7 m on a slope with < 20 degrees dip. The landslide moved southeastward with a run-out distance of similar to 100 m. Inversion analysis of the post-failure deposit geometry was conducted with the Markov Chain Monte Carlo method (MCMC) to optimize the Bingham rheological parameters of the debris. The analysis reproduced several features of the deposit geometry with a yield stress of similar to 1500 Pa and dynamic viscosity of 800-3000 Pa s. The results suggest that the shallow landslide can be approximated by the flow of a viscoplastic fluid with high-mobility debris and a maximum frontal velocity of 6-9 m/s, with a flow duration of 2-4 min.

    DOI: 10.1186/s40623-021-01443-y

    Web of Science

    researchmap

  • Influence of biopolymers on the rheological properties of seafloor sediments and the runout behavior of submarine debris flows. 国際誌

    Jun Kameda, Hamada Yohei

    Scientific reports   11 ( 1 )   1493 - 1493   2021年1月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    Submarine debris flows are mass movement processes on the seafloor, and are geohazards for seafloor infrastructure such as pipelines, communication cables, and submarine structures. Understanding the generation and run-out behavior of submarine debris flows is thus critical for assessing the risk of such geohazards. The rheological properties of seafloor sediments are governed by factors including sediment composition, grain size, water content, and physico-chemical conditions. In addition, extracellular polymeric substances (EPS) generated by microorganisms can affect rheological properties in natural systems. Here we show that a small quantity of EPS (~ 0.1 wt%) can potentially increase slope stability and decrease the mobility of submarine debris flows by increasing the internal cohesion of seafloor sediment. Our experiments demonstrated that the flow behavior of sediment suspensions mixed with an analogue material of EPS (xanthan gum) can be described by a Herschel-Bulkley model, with the rheological parameters being modified progressively, but not monotonously, with increasing EPS content. Numerical modeling of debris flows demonstrated that the run-out distance markedly decreases if even 0.1 wt% of EPS is added. The addition of EPS can also enhance the resistivity of sediment to fluidization triggered by cyclic loading, by means of formation of an EPS network that binds sediment particles. These findings suggest that the presence of EPS in natural environments reduces the likelihood of submarine geohazards.

    DOI: 10.1038/s41598-021-81186-8

    PubMed

    researchmap

  • Generation of sintered fault rock and its implications for earthquake energetics and fault healing 査読

    Tetsuro Hirono, Shunya Kaneki, Tsuyoshi Ishikawa, Jun Kameda, Naoya Tonoike, Akihiro Ito, Yuji Miyazaki

    Communications Earth & Environment   1 ( 1 )   2020年12月

     詳細を見る

    掲載種別:研究論文(学術雑誌)   出版者・発行元:Springer Science and Business Media LLC  

    Abstract

    After an earthquake, faults can recover strength through fault healing, but the mechanisms responsible are not well understood. Seismic slip may induce sintering, a bonding process between solid particles in contact under high temperatures without melting, which could produce a fault rock with elevated strength and chemical stability. Here we present results from electron microscope analyses that show a typical sintered structure in a black disk-shaped rock from the Chelungpu fault, Taiwan. This structure is experimentally reproducible in simulated fault material, prepared from the local host-rock, by heating at 800–900 °C. Through thermal and kinetic analyses of experimental materials, we show that sintering is an exothermic process which can generate energy to enhance post-slip thermochemical reactions in the fault. We propose that sintering substantially contributes to earthquake energetics and fault healing and that its occurrence can be a useful indicator of past seismic slip.

    DOI: 10.1038/s43247-020-0004-z

    researchmap

    その他リンク: http://www.nature.com/articles/s43247-020-0004-z

  • The kinetics of radical formation on mechanically activated kaolinite surfaces 査読

    Jun Kameda, Yuta Owari

    Colloids and Surfaces A: Physicochemical and Engineering Aspects   606   125421 - 125421   2020年12月

     詳細を見る

    掲載種別:研究論文(学術雑誌)   出版者・発行元:Elsevier BV  

    DOI: 10.1016/j.colsurfa.2020.125421

    researchmap

  • Cohesional slip on a plate subduction boundary during a large earthquake 査読

    Jun Kameda, Yohei Hamada

    Geophysical Research Letters   47 ( 18 )   2020年9月

     詳細を見る

  • Fault weakening caused by smectite swelling 査読

    Kameda Jun, Uno Masaoki, Conin Marianne, Ujiie Kohtaro, Hamada Yohei, Kimura Gaku

    EARTH PLANETS AND SPACE   71   2019年12月

     詳細を見る

  • Fluidized landslides triggered by the liquefaction of subsurface volcanic deposits during the 2018 Iburi-Tobu earthquake, Hokkaido 査読

    Kameda Jun, Kamiya Hiro, Masumoto Hirokazu, Morisaki Tomonori, Hiratsuka Toru, Inaoi Chisaki

    SCIENTIFIC REPORTS   9   2019年9月

  • Origin of the early Cenozoic belt boundary thrust and Izanagi–Pacific ridge subduction in the western Pacific margin 査読

    Gaku Kimura, Yujin Kitamura, Asuka Yamaguchi, Jun Kameda, Yoshitaka Hashimoto, Mari Hamahashi

    Island Arc   28 ( 5 )   2019年9月

     詳細を見る

    掲載種別:研究論文(学術雑誌)   出版者・発行元:Wiley  

    DOI: 10.1111/iar.12320

    Web of Science

    researchmap

    その他リンク: https://onlinelibrary.wiley.com/doi/full-xml/10.1111/iar.12320

  • Rheological properties of composite serpentine-brucite suspensions: Implications for mudflow behavior on forearc seamounts 査読

    Jun Kameda, Ken-ichi Hirauchi

    Marine Geology   403   191 - 196   2018年9月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:Elsevier B.V.  

    To better understand the factors that influence seafloor serpentinite mudflows, such as those recently documented on the Marianas seamounts, we have conducted rheological measurements on composite serpentine-brucite suspensions at 7 °C and a salt concentration of 0.6 M. The resulting flow curves were fitted by the Bingham fluid model, from which the Bingham yield stress and plastic viscosity of each suspension was determined. Both the yield stress and plastic viscosity increase as the water content of the suspension decreases. Increasing the brucite fraction in the solid mixture results in an increase in yield stress and a decrease in viscosity of the suspension for the same water/solid ratio. Physicochemical parameters such as pH, temperature and electrolyte concentration also moderately affect the rheology of the suspension, but the influence is not as significant as has been previously observed for suspensions containing smectite. The results suggest that mineral composition of the serpentinite mud, especially the abundance of brucite, has as much of an impact as water content on variable mudflow behaviors such as those observed at the Mariana seamounts.

    DOI: 10.1016/j.margeo.2018.06.004

    Web of Science

    Scopus

    researchmap

  • Dehydroxylation kinetics of clay minerals and its application to friction heating along an imbricate thrust in an accretionary prism 査読

    Hirokazu Masumoto, Jun Kameda, Hiroshi Arima, Kazumasa Sugiyama, Takaya Nagai, Yuzuru Yamamoto

    GEOCHEMISTRY GEOPHYSICS GEOSYSTEMS   19 ( 9 )   2991 - 3003   2018年9月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:AMER GEOPHYSICAL UNION  

    Dehydroxylation of clay minerals within fault gouges is significant for assessing transient thermogenesis due to high-velocity, frictional slip along fault zones. The clay minerals kaolinite and chlorite are common in fault zones hosted in sedimentary rocks at subduction margins. To better understand the dehydroxylation processes of these clay minerals, high-temperature X-ray diffraction analyses were carried out by using a 1:1 mixture of kaolinite and chlorite standard samples. We evaluated the kinetic parameters of each dehydroxylation reaction by thermogravimetric analysis using the Friedman method. For kaolinite, the thermogravimetric data are fitted with a one and a half order equation (F-3/2) with an activation energy of 171 kJ/mol and a frequency factor of 5.6 x 10(8) s(-1). The data for chlorite are analyzed by the geometrical contracting model equation (R-2) with an activation energy of 197 kJ/mol and a frequency factor of 4.5 x 10(9) s(-1). Thermal models of frictional heating employing this calibration show that the frictional heating can explain the reported clay mineralogy in a fossil imbricate thrust from a shallow part in an ancient accretionary prism (Shirako Fault, Japan). This result supports the previous assertion, and the observed temperature anomaly appears to demonstrate the frictional heating caused by coseismic slip on this fault.

    DOI: 10.1029/2018GC007472

    Web of Science

    researchmap

  • Thermal conductivity changes in subducting basalt, Nankai subduction zone, SW Japan: An estimation from laboratory measurements under separate high-pressure and high-temperature conditions 査読

    Lin, W, Tadai, O, Kinoshita, M, Kameda, J, Tanikawa, W, Hirose, T, Hamada, Y, Matsubayashi, O

    Geology and Tectonics of Subduction Zones: A Tribute to Gaku Kimura: Geological Society of America Special Paper   534   35 - 50   2018年8月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    DOI: 10.1130/2018.2534(02)

    Scopus

    researchmap

  • Three-dimensional texture of natural pseudotachylyte: Pseudotachylyte formation mechanism in hydrous accretionary complex 査読

    Yohei Hamada, Gaku Kimura, Jun Kameda, Asuka Yamaguchi, Mari Hamahashi, Rina Fukuchi, Yujin Kitamura, Shin'ya Okamoto

    ISLAND ARC   27 ( 2 )   2018年3月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:WILEY  

    Melt-origin pseudotachylyte is the most reliable seismogenic fault rock. It is commonly believed that pseudotachylyte generation is rare in the plate subduction zone where interstitial fluids are abundant and can trigger dynamic fault-weakening mechanisms such as thermal pressurization. Some recent studies, however, have discovered pseudotachylyte-bearing faults in exhumed ancient accretionary complexes, indicating that frictional melting also occurrs during earthquakes in subduction zones. To clarify the pseudotachylyte generation mechanism and the variation of slip behavior in the plate subduction zone, a pseudotachylyte found in the exhumed fossil accretionary complex (the Shimanto Belt, Nobeoka, Japan) was re-focused and microscopic and three-dimensional observations of the pseudotachylyte-bearing fault were performed based on optical, electron, and X-ray microscope images. Based on the patterns contained in the fragment, the pseudotachylyte is divided into four domains, although no clear domain boundaries or layering structures are not found. Three-dimensional observation also suggests that the pseudotachylyte were fragmented or isolated by cataclasite or carbonate breccia. The pseudotachylyte was rather injected into the surrounding carbonate breccia, which is composed of angular fragments of the host rock and a matrix of tiny crystalline carbonate. The pseudotachylyte volume was extracted from the X-ray microscope image and the heat abundance consumed by the pseudotachylyte generation was estimated at 2.18 MJ/m(2), which can be supplied during a slip of approximately 0.5 m. These observations and calculations, together with the results of the previous investigations, suggest hydrofracturing and rapid carbonate precipitation that preceded or accompanied the frictional melting. Dynamic hydrofracturing during a slip can be caused by rapid fluid pressurization, and can induce abrupt decrease in fluid pressure while drastically enhancing the shear strength of the shear zone. Consequently, frictional heating would be reactivated and generate the pseudotachylyte. These deformation processes can explain pseudotachylyte generation in hydrous faults with the impermeable wall rock.

    DOI: 10.1111/iar.12241

    Web of Science

    researchmap

  • Initiation of tectonic mélange formation associated with the smectite–illite transition at 2–4 km depth in a subduction zone: Hota accretionary complex, central Japan 査読

    Yamamoto Yuzuru, Kameda Jun, Fukuyama Mayuko, Yamaguchi Haruka

    Geological Society of America, Special Papers   534   115 - 127   2018年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    DOI: 10.1130/2018.2534

    Scopus

    researchmap

  • Sensitivity of Clay Suspension Rheological Properties to pH, Temperature, Salinity, and Smectite-Quartz Ratio 査読

    Jun Kameda, Tomonori Morisaki

    GEOPHYSICAL RESEARCH LETTERS   44 ( 19 )   9615 - 9621   2017年10月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:AMER GEOPHYSICAL UNION  

    Understanding the rheological properties of clay suspensions is critical to assessing the behavior of sediment gravity flows such as debris flow or turbidity current. We conducted rheological measurements of composite smectite-quartz suspensions at a temperature of 7 degrees C and a salt concentration of 0.6M. This is representative of smectite-bearing sediments under conditions on the seafloor. The flow curves obtained were fitted by the Bingham fluid model, from which we determined the Bingham yield stress and dynamic viscosity of each suspension. At a constant smectite-quartz mixing ratio, the yield stress and the dynamic viscosity tend to increase as the solid/water ratio of the suspension is increased. In the case of a constant solid/water ratio, these values increase with increasing smectite content in the smectite-quartz mixture. Additional experiments exploring differing physicochemical conditions (pH1.0-9.0; temperature 2-30 degrees C; and electrolyte (NaCl) concentration 0.2-0.6M) revealed that the influence of temperature is negligible, while pH moderately affects the rheology of the suspension. More significantly, the electrolyte concentration greatly affects the flow behavior. These variations can be explained by direct and/or indirect (double-layer) interactions between smectite-smectite particles as well as between smectite-quartz particles in the suspension. Although smectite is known as a frictionally weak material, our experimental results suggest that its occurrence can reduce the likelihood that slope failure initiates. Furthermore, smectite can effectively suppress the spreading distance once the slope has failed.

    DOI: 10.1002/2017GL075334

    Web of Science

    researchmap

  • Acoustic properties of deformed rocks in the Nobeoka thrust, in the Shimanto Belt, Kyushu, Southwest Japan 査読

    Yoshitaka Hashimoto, Shogo Abe, Hiroki Tano, Mari Hamahashi, Saneatsu Saito, Gaku Kimura, Asuka Yamaguchi, Rina Fukuchi, Jun Kameda, Yohei Hamada, Yujin Kitamura, Koichiro Fujimoto, Shoko Hina, Mio Eida

    ISLAND ARC   26 ( 4 )   e12198   2017年7月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:WILEY  

    Laboratory measurements for compressional and shear wave velocities (Vp and Vs, respectively) and porosity were conducted with core samples from the Nobeoka Thrust Drilling Project (NOBELL) under controlled effective pressure (5-65 MPa at 5 MPa intervals) and wet conditions. Samples were classified according to deformation texture as phyllite, foliated cataclasite, or non-foliated cataclasite. Measured values of Vp, Vs, and porosity are within a range of 5.17-5.57 km/s, 2.60-2.71 km/s, and 2.75-3.10 %, respectively, for phyllite; 4.89-5.23 km/s, 2.46-2.57 km/s, and 3.58-4.53 %, respectively, for foliated cataclasite; and 4.90-5.32 km/s, 2.51-2.63km/s, and 3.79-4.60 %, respectively, for non-foliated cataclasite, which are all consistent with the previous laboratory experiments conducted with outcrop samples under dry conditions. However, our results also indicate higher Vp and Vs and lower porosity than those measured by the previous studies that adopted the wire-line logging methods. The variations in Vp, Vs, and porosity are controlled by deformation structure and are greater for phyllite and foliated cataclasite than for non-foliated cataclasite.

    DOI: 10.1111/iar.12198

    Web of Science

    researchmap

  • Temporal stress variations along a seismogenic megasplay fault in the subduction zone: An example from the Nobeoka Thrust, southwestern Japan 査読

    Ryoji Kawasaki, Mari Hamahashi, Yoshitaka Hashimoto, Makoto Otsubo, Asuka Yamaguchi, Yujin Kitamura, Jun Kameda, Yohei Hamada, Rina Fukuchi, Gaku Kimura

    ISLAND ARC   26 ( 3 )   e12193   2017年5月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:WILEY  

    The Nobeoka Thrust, an ancient megasplay fault in the Shimanto Belt, southwestern Japan, contains fault rocks from the seismogenic zone, providing an accessible analog of active megasplay faults in deep subduction settings. In this study, the paleostress along the Nobeoka Thrust was analyzed using multiple inversion techniques, including k-means clustering of fault datasets acquired from drillcores that intersected the thrust. The six resultant stress orientation clusters can be divided into two general groups: stress solutions with north-south-trending sigma(1) axes, and those with east-west-trending sigma(1) axes. These groups are characterized by the temporal changes for the orientations of the sigma(1) and sigma(3) principal stress axes that involve alternation between horizontal and vertical. The findings are probably due to a change in stress state before and after earthquakes that occurred on the fault; similar changes have been observed in active tectonic settings, such as the 2011 Tohoku-Oki earthquake (Japan).

    DOI: 10.1111/iar.12193

    Web of Science

    researchmap

  • Alteration and dehydration of subducting oceanic crust within subduction zones: implications for decollement step-down and plate-boundary seismogenesis 査読

    Jun Kameda, Sayako Inoue, Wataru Tanikawa, Asuka Yamaguchi, Yohei Hamada, Yoshitaka Hashimoto, Gaku Kimura

    EARTH PLANETS AND SPACE   69   2017年4月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:SPRINGER HEIDELBERG  

    The alteration and dehydration of predominantly basaltic subducting oceanic crustal material are thought to be important controls on the mechanical and hydrological properties of the seismogenic plate interface below accretionary prisms. This study focuses on pillow basalts exposed in an ancient accretionary complex within the Shimanto Belt of southwest Japan and provides new quantitative data that provide insight into clay mineral reactions and the associated dehydration of underthrust basalts. Whole-rock and clay-fraction X-ray diffraction analyses indicate that the progressive conversion of saponite to chlorite proceeds under an almost constant bulk-rock mineral assemblage. These clay mineral reactions may persist to deep crustal levels (similar to 320 degrees C), possibly contributing to the bulk dehydration of the basalt and supplying fluid to plate-boundary fault systems. This dehydration can also cause fluid pressurization at certain horizons within hydrous basalt sequences, eventually leading to fracturing and subsequent underplating of upper basement rock into the overriding accretionary prism. This dehydration-induced breakage of the basalt can explain variations in the thickness of accreted basalt fragments within accretionary prisms as well as the reported geochemical compositions of mineralized veins associated with exposed basalts in onland locations. This fracturing of intact basalt can also nucleate seismic rupturing that would subsequently propagate along seismogenic plate interfaces.

    DOI: 10.1186/s40623-017-0635-1

    Web of Science

    researchmap

  • Opal-CT in chert beneath the toe of the Tohoku margin and its influence on the seismic aseismic transition in subduction zones 査読

    Jun Kameda, Atsushi Okamoto, Kiminori Sato, Koichiro Fujimoto, Asuka Yamaguchi, Gaku Kimura

    GEOPHYSICAL RESEARCH LETTERS   44 ( 2 )   687 - 693   2017年1月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:AMER GEOPHYSICAL UNION  

    Thick accumulation of chert is a ubiquitous feature of old oceanic plates at convergent margins. In this study, we investigate chert fragments recovered by the Integrated Ocean Drilling Program expedition 343 at the Japan Trench where the 2011 Tohoku-Oki earthquake (M-w 9.0) occurred. This sample provides a unique opportunity to investigate in situ chert diagenesis at an active subduction margin and its influence on the kinematics of megathrust faulting. Our mineralogical analyses revealed that the chert is characterized by hydrous opal-CT and may therefore be highly deformable via pressure solution creep and readily accommodate shear strain between the converging plates at driving stresses of kilopascal order. As chert diagenesis advances, any further deformation requires stresses of &gt;100MPa, given the increasing transport distances for solutes as represented in cherts on land. The chert diagenesis is thus related to the mechanical transition from a weakly to strongly coupled plate interface at this margin.

    DOI: 10.1002/2016GL071784

    Web of Science

    researchmap

  • Evolution of the Median Tectonic Line fault zone, SW Japan, during exhumation 査読

    Shigematsu, N., Kametaka, M., Inada, N., Miyawaki, M., Miyakawa, A., Kameda, J., Togo, T., Fujimoto, K.

    Tectonophysics   696   52 - 69   2017年

     詳細を見る

    掲載種別:研究論文(学術雑誌)  

    DOI: 10.1016/j.tecto.2016.12.017

    Web of Science

    researchmap

  • Source and sink of fluid in pelagic siliceous sediments along a cold subduction plate boundary 査読

    Asuka Yamaguchi, Shoko Hina, Yohei Hamada, Jun Kameda, Mari Hamahashi, Tatsu Kuwatani, Mayuko Shimizu, Gaku Kimura

    TECTONOPHYSICS   686   146 - 157   2016年8月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ELSEVIER SCIENCE BV  

    Subduction zones where old oceanic plate underthrusting occurs are characterized by thick pelagic sediments originating from planktonic ooze as well as cold thermal conditions. For a better understanding of dehydration from pelagic sediments and fluid behavior, which would play a key role in controlling the dynamics in the shallow portion of the subduction zone, as observed in the 2011 Tohoku earthquake and tsunami, we investigate cherts in a Jurassic accretionary complex in Japan. The microstructure and microchemistry of these cherts indicate dissolution of SiO2 from a pressure solution seam and precipitation of SiO2 to the "white chert layer," which would act as a fluid conduit. The amount of water necessary to precipitate SiO2 in the white chert is similar to 10(2) times larger than that produced by compaction and silica/clay diagenesis. Other fluid sources, such as hydrated oceanic crust or oceanic mantle, are necessary to account for this discrepancy in the fluid budget. A large amount of external fluid likely contributed to rising pore pressure along cold plate boundaries. (C) 2016 Elsevier B.V. All rights reserved.

    DOI: 10.1016/j.tecto.2016.07.030

    Web of Science

    researchmap

  • Exchangeable cation composition of the smectite-rich plate boundary fault at the Japan Trench 査読

    Jun Kameda, Chisaki Inaoi, Marianne Conin

    GEOPHYSICAL RESEARCH LETTERS   43 ( 7 )   3112 - 3119   2016年4月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:AMER GEOPHYSICAL UNION  

    To better understand physicochemical processes in smectite-rich fault zones, we examined exchangeable cation composition of samples from the slip zone of the 2011 Tohoku-oki earthquake (M(w)9.0) recovered by the Integrated Ocean Drilling Program Expedition 343. Our chemical analyses revealed that the exchangeable Ca2+ and Mg2+ are enriched in the slip zone, while Na+ is depleted. K+ shows a complicated depth profile probably due to K fixation. Based on fluid chemistry data, we estimated apparent selectivity coefficients of exchange reactions in the ternary Ca2+-Mg2+-Na+ system. The results suggest that the Na+ to Mg2+ exchange reaction on smectite might have progressed in the slip zone. One explanation for this feature is local progress of the reaction triggered by coseismic thermogenesis during the earthquake. Considering that the frictional property of smectite gouge is dependent on the exchangeable cation composition, chemical processes as observed in this study are intimately linked to physical aspect of smectite-bearing faults.

    DOI: 10.1002/2016GL068283

    Web of Science

    researchmap

  • Hydrogeological responses to incoming materials at the erosional subduction margin, offshore Osa Peninsula, Costa Rica 査読

    Jun Kameda, Robert N. Harris, Mayuko Shimizu, Kohtaro Ujiie, Akito Tsutsumi, Minoru Ikehara, Masaoki Uno, Asuka Yamaguchi, Yohei Hamada, Yuka Namiki, Gaku Kimura

    GEOCHEMISTRY GEOPHYSICS GEOSYSTEMS   16 ( 8 )   2725 - 2742   2015年9月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:AMER GEOPHYSICAL UNION  

    Bulk mineral assemblages of sediments and igneous basement rocks on the incoming Cocos Plate at the Costa Rica subduction zone are examined by X-ray diffraction analyses on core samples. These samples are from Integrated Ocean Drilling Program Expedition 334 reference Site U1381, similar to 5 km seaward of the trench. Drilling recovered approximately 100 m of sediment and 70 m of igneous oceanic basement. The sediment includes two lithologic units: hemipelagic clayey mud and siliceous to calcareous pelagic ooze. The hemipelagic unit is composed of clay minerals (similar to 50 wt.%), quartz (similar to 5 wt.%), plagioclase (similar to 5 wt.%), calcite (similar to 15 wt.%) and similar to 30 wt.% of amorphous materials, while the pelagic unit is mostly made up of biogenic amorphous silica (similar to 50 wt.%) and calcite (similar to 50 wt.%). The igneous basement rock consists of plagioclase (similar to 50-60 wt.%), clinopyroxene (similar to>25 wt.%), and saponite (similar to 15-40 wt.%). Saponite is more abundant in pillow basalt than in the massive section, reflecting the variable intensity of alteration. We estimate the total water influx of the sedimentary package is 6.9 m(3)/yr per m of trench length. Fluid expulsion models indicate that sediment compaction during shallow subduction causes the release of pore water while peak mineral dehydration occurs at temperatures of approximately similar to 100 degrees C, 40-30 km landward of the trench. This region is landward of the observed updip extent of seismicity. We posit that in this region the presence of subducting bathymetric relief capped by velocity weakening nannofossil chalk is more important in influencing the updip extent of seismicity than the thermal regime.

    DOI: 10.1002/2015GC005837

    Web of Science

    researchmap

  • Deformation structures in the frontal prism near the Japan Trench: Insights from sandbox models 査読

    Santanu Bose, Puspendu Saha, James J. Mori, Christie Rowe, Kohtaro Ujiie, Frederick M. Chester, Marianne Conin, Christine Regalla, Jun Kameda, Virginia Toy, James Kirkpatrick, Francesca Remitti, J. Casey Moore, Monica Wolfson-Schwehr, Yasuyuki Nakamura, Anchit Gupta

    JOURNAL OF GEODYNAMICS   89   29 - 38   2015年9月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:PERGAMON-ELSEVIER SCIENCE LTD  

    We have used sandbox experiments to explore the mechanics of the frontal prism structures documented by seismic reflection data and new borehole from IODP Expedition 343 (JFAST). This study investigated the effects of down-dip (normal to trench axis) variations in frictional resistance along a decollement on the structural development of the frontal wedges near subduction zones. Interpretation of seismic reflection images indicates that the wedge has been effected by trench-parallel horst-and-graben structures in the subducting plate. We performed sandbox experiments with down-dip patches of relatively high and low friction on the basal decollement to simulate the effect of variable coupling over subducting oceanic plate topography. Our experiments verify that high frictional resistance on the basal fault can produce the internal deformation and fault-and-fold structures observed in the frontal wedge by the JFAST expedition. Subduction of patches of varying friction caused a temporal change in the style of internal deformation within the wedge and gave rise to two distinctive structural domains, separated by a break in the surface slope of the wedge: (i) complexly deformed inner wedge with steep surface slope and (ii) shallow taper outer wedge, with a sequence of imbricate thrusts. Our experiments further demonstrate that the topographic slope-break in the wedge develops when the hinterland part of the wedge essentially stops deforming internally, leading to in-sequence thrusting with the formation of an outer wedge with low taper angle. For a series of alternate high and low frictional conditions on the basal fault the slope of the wedge varies temporally between a topographic slope-break and uniformly sloping wedge. (C) 2015 Elsevier Ltd. All rights reserved.

    DOI: 10.1016/j.jog.2015.06.002

    Web of Science

    researchmap

  • Estimation of slip rate and fault displacement during shallow earthquake rupture in the Nankai subduction zone 査読

    Yohei Hamada, Arito Sakaguchi, Wataru Tanikawa, Asuka Yamaguchi, Jun Kameda, Gaku Kimura

    EARTH PLANETS AND SPACE   67   2015年3月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:SPRINGER HEIDELBERG  

    Enormous earthquakes repeatedly occur in subduction zones, and the slips along megathrusts, in particular those propagating to the toe of the forearc wedge, generate ruinous tsunamis. Quantitative evaluation of slip parameters (i.e., slip velocity, rise time and slip distance) of past slip events at shallow, tsunamigenic part of the fault is critical to characterize such earthquakes. Here, we attempt to quantify these parameters of slips that may have occurred along the shallow megasplay fault and the plate boundary decollement in the Nankai Trough, off southwest Japan. We apply a kinetic modeling to vitrinite reflectance profiles on the two fault rock samples obtained from Integrated Ocean Drilling Program (IODP). This approach constitutes two calculation procedures: heat generation and numerical profile fitting of vitrinite reflectance data. For the purpose of obtaining optimal slip parameters, residue calculation is implemented to estimate fitting accuracy. As the result, the measured distribution of vitrinite reflectance is reasonably fitted with heat generation rate (Q) over dot and slip duration (t(r)) of 16,600 J/s/m(2) and 6,250 s, respectively, for the megasplay and 23,200 J/s/m(2) and 2,350 s, respectively, for the frontal decollement, implying slow and long-term slips. The estimated slip parameters are then compared with previous reports. The maximum temperature, Tmax, for the Nankai megasplay fault is consistent with the temperature constraint suggested by a previous work. Slow slip velocity, long-term rise time, and large displacement are recognized in these fault zones (both of the megasplay, the frontal decollement). These parameters are longer and slower than typical coseismic slip, but are rather consistent with rapid afterslip.

    DOI: 10.1186/s40623-015-0208-0

    Web of Science

    researchmap

  • Pelagic smectite as an important factor in tsunamigenic slip along the Japan Trench 査読

    Jun Kameda, Mayuko Shimizu, Kohtaro Ujiie, Takehiro Hirose, Matt Ikari, James Mori, Kiyokazu Oohashi, Gaku Kimura

    GEOLOGY   43 ( 2 )   155 - 158   2015年2月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:GEOLOGICAL SOC AMER, INC  

    The very large slip on the shallow portion of the subduction interface during the 2011 Tohoku-oki earthquake (M-w 9.0) caused a huge tsunami along the northeast coast of Honshu, Japan. In order to elucidate the mechanics of such tsunamigenic slip, the Integrated Ocean Drilling Program Expedition 343 (Japan Trench Fast Drilling Project, JFAST), was carried out one year after the earthquake and succeeded in recovering rocks constituting the active plate boundary fault. Our mineralogical analyses using X-ray diffraction reveal that the shallow portion of the fault zone that caused the earthquake is significantly enriched in smectite compared to the surrounding sediments, which may be intimately linked to the tsunamigenic shallow faulting. For comparison, we also analyzed mineralogical features of incoming sediments just prior to subduction, recovered on the outer rise of the Japan Trench (Site 436, Deep Sea Drilling Project Leg 56), and found a characteristic smectite-rich horizon in the uppermost similar to 5 m of the pelagic clay layer. This horizon should be mechanically weak and will become the future plate boundary fault, as observed in the JFAST cores. The smectite-rich deposits are broadly distributed in the northwestern Pacific Ocean, and may therefore potentially enhance conditions for large shallow slip during earthquakes that occur over a broad area of the Japan Trench plate boundary, which would result in large tsunamis for this region.

    DOI: 10.1130/G35948.1

    Web of Science

    researchmap

  • Strength characteristics of Japan Trench borehole samples in the high-slip region of the 2011 Tohoku-Oki earthquake 査読

    Matt J. Ikari, Jun Kameda, Demian M. Saffer, Achim J. Kopf

    EARTH AND PLANETARY SCIENCE LETTERS   412   35 - 41   2015年2月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ELSEVIER SCIENCE BV  

    The 2011 Tohoku-Oki earthquake demonstrated that the shallowest reaches of plate boundary subduction megathrusts can host substantial coseismic slip that generates large and destructive tsunamis, contrary to the common assumption that the frictional properties of unconsolidated clay-rich sediments at depths less than similar to 5 km should inhibit rupture. We report on laboratory shearing experiments at low sliding velocities (&lt;1 mm/s) using borehole samples recovered during IODP Expedition 343 (JFAST), spanning the plate-boundary decollement within the region of large coseismic slip during the Tohoku earthquake. We show that at sub-seismic slip rates the fault is weak (sliding friction mu(s) = 0.2-0.26), in contrast to the much stronger wall rocks (mu(s) &gt; similar to 0.5). The fault is weak due to elevated smectite clay content and is frictionally similar to a pelagic clay layer of similar composition. The higher cohesion of intact wall rock samples coupled with their higher amorphous silica content suggests that the wall rock is stronger due to diagenetic cementation and low clay content. Our measurements also show that the strongly developed in-situ fabric in the fault zone does not contribute to its frictional weakness, but does lead to a near-cohesionless fault zone, which may facilitate rupture propagation by reducing shear strength and surface energy at the tip of the rupture front. We suggest that the shallow rupture and large coseismic slip during the 2011 Tohoku earthquake was facilitated by a weak and cohesionless fault combined with strong wall rocks that drive localized deformation within a narrow zone. (C) 2014 Elsevier B.V. All rights reserved.

    DOI: 10.1016/j.epsl.2014.12.014

    Web of Science

    researchmap

  • Multiple damage zone structure of an exhumed seismogenic megasplay fault in a subduction zone - a study from the Nobeoka Thrust Drilling Project 査読

    Mari Hamahashi, Yohei Hamada, Asuka Yamaguchi, Gaku Kimura, Rina Fukuchi, Saneatsu Saito, Jun Kameda, Yujin Kitamura, Koichiro Fujimoto, Yoshitaka Hashimoto

    EARTH PLANETS AND SPACE   67   2015年2月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:SPRINGEROPEN  

    To investigate the mechanical properties and deformation patterns of megathrusts in subduction zones, we studied damage zone structures of the Nobeoka Thrust, an exhumed megasplay fault in the Kyushu Shimanto Belt, using drill cores and geophysical logging data obtained during the Nobeoka Thrust Drilling Project. The hanging wall, composed of a turbiditic sequence of phyllitic shales and sandstones, and the footwall, consisting of a melange of a shale matrix with sandstone and basaltic blocks, exhibit damage zones that include multiple sets of 'brecciated zones' intensively broken in the mudstone-rich intervals, sandwiched by 'surrounding damage zones' in the sandstone-rich intervals with cohesive faults and mineral veins. The fracture zones are thinner (2.7 to 5.5 m) in the sandstone-rich intervals and thicker in the shale-dominant intervals (2.3 to 18.6 m), which indicates a preference of coseismic slip and velocity-weakening in the former, and aseismic deformation in the latter. However, the surrounding damage zones observed in the current study are associated with an increase in resistivity, P-wave velocity, and density and a decrease in porosity, inferring densification and strain-hardening in the sandstone-rich intervals and strain-weakening in the mudstone-rich intervals. These observations indicate that the sandstone-rich damage zones may weaken in the short term but may strengthen in the geologically long term, contributing to a later stage of fault activity. In contrast, the mudstone-rich damage zones may strengthen in the short term but develop weak structures through longer time periods. The observed shear zone thickness in the hanging wall is thinner (2.3 to 18.6 m) compared to the footwall damage zones (12 to 39.9 m), possibly because faults in the hanging wall were concentrated and partitioned between the preexisting turbiditic sequence of alternating shale/ sandstone-dominant intervals, whereas in the footwall, faults were more sporadically distributed throughout the sandstone block-in-matrix cataclasites. A splay fault may evolve and be characterized by physical property contrasts, the lithology dependence of deformation, and the variability of damage zone thickness due to a heterogeneous lithology distribution in the hanging wall and footwall. The deformation patterns observed in the Nobeoka Thrust provide insights to the strain-hardening/weakening behaviors of sediments along megathrusts over geological timescales.

    DOI: 10.1186/s40623-015-0186-2

    Web of Science

    researchmap

  • Structure and lithology of the Japan Trench subduction plate boundary fault 査読

    James D. Kirkpatrick, Christie D. Rowe, Kohtaro Ujiie, J. Casey Moore, Christine Regalla, Francesca Remitti, Virginia Toy, Monica Wolfson-Schwehr, Jun Kameda, Santanu Bose, Frederick M. Chester

    TECTONICS   34 ( 1 )   53 - 69   2015年1月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:AMER GEOPHYSICAL UNION  

    The 2011 M(w)9.0 Tohoku-oki earthquake ruptured to the trench with maximum coseismic slip located on the shallow portion of the plate boundary fault. To investigate the conditions and physical processes that promoted slip to the trench, Integrated Ocean Drilling Program Expedition 343/343T sailed 1 year after the earthquake and drilled into the plate boundary approximate to 7 km landward of the trench, in the region of maximum slip. Core analyses show that the plate boundary decollement is localized onto an interval of smectite-rich, pelagic clay. Subsidiary structures are present in both the upper and lower plates, which define a fault zone approximate to 5-15m thick. Fault rocks recovered from within the clay-rich interval contain a pervasive scaly fabric defined by anastomosing, polished, and lineated surfaces with two predominant orientations. The scaly fabric is crosscut in several places by discrete contacts across which the scaly fabric is truncated and rotated, or different rocks are juxtaposed. These contacts are inferred to be faults. The plate boundary decollement therefore contains structures resulting from both distributed and localized deformation. We infer that the formation of both of these types of structures is controlled by the frictional properties of the clay: the distributed scaly fabric formed at low strain rates associated with velocity-strengthening frictional behavior, and the localized faults formed at high strain rates characterized by velocity-weakening behavior. The presence of multiple discrete faults resulting from seismic slip within the decollement suggests that rupture to the trench may be characteristic of this margin.

    DOI: 10.1002/2014TC003695

    Web of Science

    researchmap

  • Friction properties of the plate boundary megathrust beneath the frontal wedge near the Japan Trench: an inference from topographic variation 査読

    Hiroaki Koge, Toshiya Fujiwara, Shuichi Kodaira, Tomoyuki Sasaki, Jun Kameda, Yujin Kitamura, Mari Hamahashi, Rina Fukuchi, Asuka Yamaguchi, Yohei Hamada, Juichiro Ashi, Gaku Kimura

    EARTH PLANETS AND SPACE   66   2014年11月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:SPRINGER  

    The 2011 Tohoku-Oki earthquake (Mw 9.0) produced a fault rupture that extended to the toe of the Japan Trench. The deformation and frictional properties beneath the forearc are keys that can help to elucidate this unusual event. In the present study, to investigate the frictional properties of the shallow part of the plate boundary, we applied the critically tapered Coulomb wedge theory to the Japan Trench and obtained the effective coefficient of basal friction (mu(b)') and Hubbert-Rubey pore fluid pressure ratio (lambda) of the wedge beneath the lower slope. We extracted the surface slope angle and decollement dip angle (which are the necessary topographic parameters for applying the critical taper theory) from seismic reflection and refraction survey data at 12 sites in the frontal wedges of the Japan Trench. We found that the angle between the decollement and back-stop interface generally decreases toward the north. The measured taper angle and inferred effective friction coefficient were remarkably high at three locations. The southernmost area, which had the highest coefficient of basal friction, coincides with the area where the seamount is colliding offshore of Fukushima. The second area with a high effective coefficient of basal friction coincides with the maximum slip location during the 2011 Tohoku-Oki earthquake. The area of the 2011 earthquake rupture was topographically unique from other forearc regions in the Japan Trench. The strain energy accumulation near the trench axis may have proceeded because of the relatively high friction, and later this caused a large slip and collapse of the wedge. The location off Sanriku, where there are neither seamount collisions nor rupture propagation, also has a high coefficient of basal friction. The characteristics of the taper angle, effective coefficient of basal friction, and pore fluid pressure ratio along the Japan Trench presented herein may contribute to the understanding of the relationship between the geometry of the prism and the potential for generating seismo-tsunamigenic slips.

    DOI: 10.1186/s40623-014-0153-3

    Web of Science

    researchmap

  • Changes in illite crystallinity within an ancient tectonic boundary thrust caused by thermal, mechanical, and hydrothermal effects: an example from the Nobeoka Thrust, southwest Japan 査読

    Rina Fukuchi, Koichiro Fujimoto, Jun Kameda, Mari Hamahashi, Asuka Yamaguchi, Gaku Kimura, Yohei Hamada, Yoshitaka Hashimoto, Yujin Kitamura, Saneatsu Saito

    EARTH PLANETS AND SPACE   66   2014年9月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:SPRINGEROPEN  

    Illite crystallinity (IC), the full width at half maximum of the illite (001) peak in clay-fraction X-ray diffraction (XRD), is a common geothermometer widely applied to various tectonic settings. Paleotemperature estimation using IC presents methodological ambiguity because IC is not only affected by background temperature but also by mechanical, hydrothermal, and surface weathering effects. To clarify the influences of these effects on IC in the fault zone, we analyzed the IC and the illite 001 peak intensity of continuous borehole core samples from the Nobeoka Thrust, a fossilized tectonic boundary thrust in the Shimanto Belt, the Cretaceous-Paleogene Shimanto accretionary complex in southwest Japan. We also carried out grinding experiments on borehole core samples and sericite standard samples as starting materials and investigated the effect of mechanical comminution on the IC and illite peak intensity of the experimental products. We observed the following: (1) the paleotemperatures of the hanging wall and footwall of the Nobeoka Thrust are estimated to be 288 degrees C to 299 degrees C and 198 degrees C to 249 degrees C, respectively, which are approximately 20 degrees C to 30 degrees C lower than their previously reported temperatures estimated by vitrinite reflectance; (2) the fault core of the Nobeoka Thrust does not exhibit IC decrease; (3) the correlation of IC and illite peak intensity in the hanging wall damage zone were well reproduced by the grinding experiment, suggesting that the effect of mechanical comminution increases toward the fault core and; (4) the abrupt increase in IC value accompanied by high illite peak intensity is explained by hydrothermal alterations including plagioclase breakdown and the formation of white micas. Our results indicate that IC has potential for quantifying the effects of mechanical comminution and hydrothermal alteration within a fault zone.

    DOI: 10.1186/1880-5981-66-116

    Web of Science

    researchmap

  • Frictional properties of sediments entering the Costa Rica subduction zone offshore the Osa Peninsula: implications for fault slip in shallow subduction zones 査読

    Yuka Namiki, Akito Tsutsumi, Kohtaro Ujiie, Jun Kameda

    EARTH PLANETS AND SPACE   66   2014年7月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:SPRINGER HEIDELBERG  

    examined the frictional properties of sediments on the Cocos plate offshore the Osa Peninsula, Costa Rica, and explored variations in the intrinsic frictional properties of the sediment inputs to the Costa Rica subduction zone. Sediment samples were collected at Site U1381A during the Integrated Ocean Drilling Program Expedition 334, and include hemipelagic clay to silty clay material (Unit I) and pelagic silicic to calcareous ooze (Unit II). The frictional properties of the samples were tested at a normal stress of 5 MPa under water-saturated conditions and with slip velocities ranging from 0.0028 to 2.8 mm/s for up to 340 mm of displacement. The experimental results reveal that the steady-state friction coefficient values of clay to silty clay samples are as low as similar to 0.2, whereas those of silicic to calcareous ooze samples are as high as 0.6 to 0.8. The clay to silty clay samples show a positive dependence of friction on velocity for all tested slip velocities. In contrast, the silicic to calcareous ooze samples show a negative dependence of friction on velocity at velocities of 0.0028 to 0.28 mm/s and either neutral or positive dependence at velocities higher than 0.28 mm/s. Given the low frictional coefficient values observed for the clay to silty clay samples of Unit I, the decollement at the Costa Rica Seismogenesis Project transect offshore the Osa Peninsula likely initiates in Unit I and is initially very weak. In addition, the velocity-strengthening behavior of the clay to silty clay suggests that faults in the very shallow portion of the Costa Rica subduction zone are stable and thus behave as creeping segments. In contrast, the velocity-weakening behavior of the silicic to calcareous ooze favors unstable slip along faults. The shallow seismicity occurred at a depth as shallow as similar to 9 km along the Costa Rica margin offshore the Osa Peninsula (M-w 6.4, June 2002), indicating that materials characterized by velocity-weakening behavior constitute the fault zone at the depth of the seismicity. Fault slip nucleating along a fault in Unit II would be a likely candidate for the source of the shallow earthquake event.

    DOI: 10.1186/1880-5981-66-72

    Web of Science

    researchmap

  • Frictional properties of incoming pelagic sediments at the Japan Trench: implications for large slip at a shallow plate boundary during the 2011 Tohoku earthquake 査読

    Michiyo Sawai, Takehiro Hirose, Jun Kameda

    EARTH PLANETS AND SPACE   66   2014年7月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:SPRINGER HEIDELBERG  

    The 2011 Tohoku earthquake (Mw 9.0) produced a very large slip on the shallow part of a megathrust fault that resulted in destructive tsunamis. Although multiple causes of such large slip at shallow depths are to be expected, the frictional property of sediments around the fault, particularly at coseismic slip velocities, may significantly contribute to large slip along such faults. We have thus investigated the frictional properties of incoming pelagic sediments that will subduct along the plate boundary fault at the Tohoku subduction zone, in order to understand the rupture processes that can cause large slip in the shallow parts of subduction zones. Our experimental results on clayey sediment at the base of the sedimentary section on the Pacific Plate yield a low friction coefficient of &lt;0.2 over a wide range of slip velocities (0.25 mm/s to 1.3 m/s), and extremely low fracture energy during slip weakening, as compared with previous experiments of disaggregated sediments under coseismic slip conditions. Integrated Ocean Drilling Program (IODP) Expedition 343 confirmed that the clay-rich sediment investigated here is identical to those in the plate boundary fault zone, which ruptured and generated the Tohoku earthquake. The present results suggest that smectite-rich pelagic sediment not only accommodates cumulative plate motion over interseismic periods but also energetically facilitates the propagation of earthquake rupture towards the shallow part of the Tohoku subduction zone.

    DOI: 10.1186/1880-5981-66-65

    Web of Science

    researchmap

  • Re-evaluation of frictional heat recorded in the dark gouge of the shallow part of a megasplay fault at the Nankai Trough 査読

    Tetsuro Hirono, Tsuyoshi Ishikawa, Hirokazu Masumoto, Jun Kameda, Hikaru Yabuta, Hideki Mukoyoshi

    TECTONOPHYSICS   626   157 - 169   2014年6月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ELSEVIER SCIENCE BV  

    Because a megasplay fault branching from the deep subduction boundary megathrust in the Nankai Trough is thought to be the source of large tsunamis associated with past Tonankai earthquakes, investigation of the heat signal due to frictional slip recorded in the fault is important for estimating the earthquake slip parameters. We performed X-ray diffraction and infrared spectroscopic analyses of a megasplay fault-rock sample and re-examined previously reported trace-element and isotope compositions, but observed no specific change related to high temperature (&gt;= 250 degrees C). In addition, although a qualitative increase of the illite content in illite/smectite mixed-layer minerals within the slip-zone sample was previously reported, our kinetic evaluation of illitization, taking into consideration the coseismic temperature change due to frictional heating and heat conduction, revealed that the illitization reaction hardly progresses at temperatures under 250 degrees C. Alternatively, we suggest that the illite content in mixed-layer minerals might increase progressively via a comminution-dissolution-recrystallization process during multiple past slips. Accurate assessment of the slip behavior of the megasplay fault could be efficiently obtained by drilling to penetrate the fault zone at a deeper depth of approximately 1.5 km, where records of high temperatures would be detectable. (C) 2014 Elsevier B.V. All rights reserved.

    DOI: 10.1016/j.tecto.2014.04.020

    Web of Science

    researchmap

  • Geochemical and mineralogical characteristics of fault gouge in the Median Tectonic Line, Japan: evidence for earthquake slip 査読

    Tsuyoshi Ishikawa, Tetsuro Hirono, Noriko Matsuta, Kazuro Kawamoto, Koichiro Fujimoto, Jun Kameda, Yoshiro Nishio, Yuka Maekawa, Go Honda

    EARTH PLANETS AND SPACE   66   2014年5月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:SPRINGER HEIDELBERG  

    We carried out geochemical and mineralogical analyses on fault-zone rocks from the Anko section of the Median Tectonic Line in Nagano Prefecture, Japan, to investigate coseismic physicochemical processes in the fault zone. The latest fault zone in the Anko section contains cataclasite, fault breccia, and fault gouge of granitic composition, and brecciated basic schist. Protoliths of the granitic composition are from the Ryoke metamorphic belt and those of the basic schist from the Sambagawa metamorphic belt. X-ray diffraction analyses show a selective decrease of clay minerals coupled with an increase of amorphous phase in an intensely deformed layer of black gouge (5- to 10-cm thick). SEM observation reveals that the black gouge is characterized by a drastic reduction of grain size and abundant ultrafine particles of submicrometer to several tens of nanometers with well-rounded spheroidal shapes. These observations for the black gouge are indicative of strong mineral lattice distortion and granulation associated with earthquake slip. Geochemically, the black gouge is characterized by distinctly higher Li content and Sr-87/Sr-86 isotope ratio than surrounding cataclasites, breccias, and gouges, which have similar major element compositions. Model analysis reveals that the trace element composition of the black gouge is consistent with high-temperature (up to 250A degrees C) coseismic fluid-rock interactions. Thermal and kinetic constraints indicate that there have been repeated slips on the fault at moderate depths (e.g., 600 m), although the tectonic process by which the fault zone has been uplifted and exposed in this area is not well understood.

    DOI: 10.1186/1880-5981-66-36

    Web of Science

    researchmap

  • Mineral assemblage anomalies in the slip zone of the 1999 Taiwan Chi-Chi earthquake: Ultrafine particles preserved only in the latest slip zone 査読

    Tetsuro Hirono, Jun Kameda, Hiroki Kanda, Wataru Tanikawa, Tsuyoshi Ishikawa

    GEOPHYSICAL RESEARCH LETTERS   41 ( 9 )   3052 - 3059   2014年5月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:AMER GEOPHYSICAL UNION  

    We determined mineral assemblages of samples from the Taiwan Chelungpu fault and from milling and heating experiments by using X-ray diffraction and scanning and transmission electron microscopy. The fault system contains three dominant fault zones, the shallowest of which slipped during the 1999 Chi-Chi earthquake. The quartz and clay mineral contents of the primary slip zone were low, and it contained partly amorphous ultrafine particles (several tens of nanometers). Up to 30 weight percent of materials in that zone could not be fit to standard diffraction patterns, whereas nearly 100 weight percent of those in surrounding samples could be. The unfitted component could be attributed to the observed ultrafine particles produced by comminution during the earthquake, because weak diffraction intensities are caused from mineral lattice distortion, granulation, and amorphous coatings. Such particles are a potential proxy for identifying the slip zone of the most recent earthquake along a fault.

    DOI: 10.1002/2014GL059805

    Web of Science

    researchmap

  • Quartz deposition and its influence on the deformation process of megathrusts in subduction zones 査読

    Jun Kameda, Kuniyo Kawabata, Yohei Hamada, Asuka Yamaguchi, Gaku Kimura

    EARTH PLANETS AND SPACE   66   2014年4月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:SPRINGEROPEN  

    We present a quantitative examination of the liberation and subsequent deposition of silica at the subduction zone plate interface in the Mugi melange, an exhumed accretionary complex in the Shimanto Belt of southwest Japan. Frequency and thickness measurements indicate that mineralized veins hosted in deformed shales make up approximately 0.4% of the volume of this exposure. In addition, whole-rock geochemical evidence suggests that the net volume of SiO2 liberated from the melange at temperatures of < 200 degrees C was as much as 35%, with up to 40% of the SiO2 loss related to the smectite-illite (S-I) conversion reaction, and the rest attributable to the pressure solution of detrital quartz and feldspar. Kinetic modeling of the S-I reaction indicates active liberation of SiO2 at approximately 70 degrees C to 200 degrees C, with peak SiO2 loss at around 100 degrees C, although these estimates should be slightly shifted toward lower temperature conditions based on X-ray diffraction (XRD) analyses of mixed-layer S-I in the Mugi melange. The onset of pressure solution was not fully constrained, but has been documented to occur at around 150 degrees C in the study area. The deposition in deformed shales of quartz liberated by pressure solution and the S-I reaction is probably linked to seismogenic behavior along the plate interface by (1) progressively enhanced velocity-weakening properties, which are favorable for unstable seismogenic faulting, including very-low-frequency earthquakes and (2) increasing intrinsic frictional strength, which leads to a step-down of the plate boundary decollement into oceanic basalt.

    DOI: 10.1186/1880-5981-66-13

    Web of Science

    researchmap

  • The influence of organic-rich shear zones on pelagic sediment deformation and seismogenesis in a subduction zone 査読

    Jun Kameda, Yui Kouketsu, Mayuko Shimizu, Asuka Yamaguchi, Yohei Hamada, Mari Hamahashi, Hiroaki Koge, Rina Fukuchi, Masayuki Ikeda, Toshihiro Kogure, Gaku Kimura

    JOURNAL OF MINERALOGICAL AND PETROLOGICAL SCIENCES   109 ( 5 )   228 - 238   2014年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:JAPAN ASSOC MINERALOGICAL SCIENCES  

    We have examined the mineralogy and deformation of black shear zones containing abundant carbonaceous materials (CM) and clay minerals in bedded ribbon cherts in a Jurassic accretionary complex, central Japan. Microtextural observations indicate that pressure solution and cataclastic deformation were the primary deformation mechanisms in the cherts. Whole-rock mineral compositions were quantitatively investigated using X-ray diffraction, Raman spectroscopy, and a CHN elemental analyzer. The results show that the samples contain variable amounts of CM and clay minerals, up to 17 wt% and 60 wt%, respectively. Moreover, the clay and CM contents in the samples, including the host rock cherts, show a positive correlation represented by a single compositional trend, and this may be explained by the progressive concentration of clays and CM due to pressure solution and the removal of soluble quartz or mass transfer processes associated with deformation. Intact cherts dominated by quartz seem to provide plausible source rocks for the nucleation of seismic slip including slow slip events, while the abundant CM and clays as observed in the black shear zones may have effectively weakened and stabilized the sliding behavior. These results are important for understanding deformation processes in the Japan Trench.

    DOI: 10.2465/jmps.140403

    Web of Science

    researchmap

  • Low Coseismic Shear Stress on the Tohoku-Oki Megathrust Determined from Laboratory Experiments 査読

    Kohtaro Ujiie, Hanae Tanaka, Tsubasa Saito, Akito Tsutsumi, James J. Mori, Jun Kameda, Emily E. Brodsky, Frederick M. Chester, Nobuhisa Eguchi, Sean Toczko

    SCIENCE   342 ( 6163 )   1211 - 1214   2013年12月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:AMER ASSOC ADVANCEMENT SCIENCE  

    Large coseismic slip was thought to be unlikely to occur on the shallow portions of plate-boundary thrusts, but the 11 March 2011 Tohoku-Oki earthquake [moment magnitude (M-w) = 9.0] produced huge displacements of similar to 50 meters near the Japan Trench with a resultant devastating tsunami. To investigate the mechanisms of the very large fault movements, we conducted high-velocity (1.3 meters per second) friction experiments on samples retrieved from the plate-boundary thrust associated with the earthquake. The results show a small stress drop with very low peak and steady-state shear stress. The very low shear stress can be attributed to the abundance of weak clay (smectite) and thermal pressurization effects, which can facilitate fault slip. This behavior provides an explanation for the huge shallow slip that occurred during the earthquake.

    DOI: 10.1126/science.1243485

    Web of Science

    researchmap

  • Contrasts in physical properties between the hanging wall and footwall of an exhumed seismogenic megasplay fault in a subduction zone-An example from the Nobeoka Thrust Drilling Project 査読

    Mari Hamahashi, Saneatsu Saito, Gaku Kimura, Asuka Yamaguchi, Rina Fukuchi, Jun Kameda, Yohei Hamada, Yujin Kitamura, Koichiro Fujimoto, Yoshitaka Hashimoto, Shoko Hina, Mio Eida

    Geochemistry, Geophysics, Geosystems   14 ( 12 )   5354 - 5370   2013年12月

     詳細を見る

    掲載種別:研究論文(学術雑誌)   出版者・発行元:American Geophysical Union (AGU)  

    DOI: 10.1002/2013gc004818

    Web of Science

    researchmap

  • Structure and Composition of the Plate-Boundary Slip Zone for the 2011 Tohoku-Oki Earthquake 査読

    Frederick M. Chester, Christie Rowe, Kohtaro Ujiie, James Kirkpatrick, Christine Regalla, Francesca Remitti, J. Casey Moore, Virginia Toy, Monica Wolfson-Schwehr, Santanu Bose, Jun Kameda, James J. Mori, Emily E. Brodsky, Nobuhisa Eguchi, Sean Toczko

    SCIENCE   342 ( 6163 )   1208 - 1211   2013年12月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:AMER ASSOC ADVANCEMENT SCIENCE  

    The mechanics of great subduction earthquakes are influenced by the frictional properties, structure, and composition of the plate-boundary fault. We present observations of the structure and composition of the shallow source fault of the 2011 Tohoku-Oki earthquake and tsunami from boreholes drilled by the Integrated Ocean Drilling Program Expedition 343 and 343T. Logging-while-drilling and core-sample observations show a single major plate-boundary fault accommodated the large slip of the Tohoku-Oki earthquake rupture, as well as nearly all the cumulative interplate motion at the drill site. The localization of deformation onto a limited thickness (less than 5 meters) of pelagic clay is the defining characteristic of the shallow earthquake fault, suggesting that the pelagic clay may be a regionally important control on tsunamigenic earthquakes.

    DOI: 10.1126/science.1243719

    Web of Science

    researchmap

  • Progress of illitization along an imbricate frontal thrust at shallow depths in an accretionary prism 査読

    Jun Kameda, Yuzuru Yamamoto, Yohei Hamada, Koichiro Fujimoto, Gaku Kimura

    TECTONOPHYSICS   600   41 - 51   2013年7月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ELSEVIER SCIENCE BV  

    Fossil imbricate thrusts, branching from a decollement in an ancient accretionary prism (the Miura-Boso accretionary prism), are exposed in the southern parts of the Miura and Boso peninsulas in central Japan. An analysis of the clay mineralogy of fault rocks along one of the imbricate thrust faults, the Shirako Fault, revealed local illitization of mixed-layer illite-smectite (I-S) and the partial breakdown of kaolinite. The shape of the I(001)-S(001) reflection in the X-ray diffraction pattern suggests that the illite fraction in I-S crystallites within the fault gouge is similar to 9% more than in the surrounding rocks. These results imply that there has been a local temperature anomaly within the slip zone, attributable to frictional heating induced by high-velocity slip. A thermal model, coupled with a kinetic simulation of illitization in I-S, suggests that the reaction was probably facilitated by multiple high-velocity slips at a peak temperature of similar to 450 degrees C, suggesting repeated seismic rupture propagations to the prism toe, as also inferred from the modern accretionary prism (in the Nankai Trough). (C) 2013 Elsevier B.V. All rights reserved.

    DOI: 10.1016/j.tecto.2013.04.024

    Web of Science

    researchmap

  • Hanging wall deformation of a seismogenic megasplay fault in an accretionary prism: The Nobeoka Thrust in southwestern Japan 査読

    Gaku Kimura, Mari Hamahashi, Shin'ya Okamoto, Asuka Yamaguchi, Jun Kameda, Hugues Raimbourg, Yohei Hamada, Haruka Yamaguchi, Tadahiro Shibata

    JOURNAL OF STRUCTURAL GEOLOGY   52   136 - 147   2013年7月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:PERGAMON-ELSEVIER SCIENCE LTD  

    The structure and occurrence of deformation within the hanging wall of the Nobeoka Thrust in Kyushu, Japan, was investigated to understand the dynamic aspects of splay faulting in relation to seismic events. From field observations, hanging wall is suggested to have undergone four phases of deformation. The first phase involved horizontal shortening, as documented by folding and thrusting, followed by a phase of vertical loading shown by the development of horizontal slaty cleavages, pressure solution, and cleavage-parallel mineral vein precipitation. A third phase involved shearing, and deformation along cleavage restricted to near the Nobeoka Thrust, while the fourth phase produced widespread, brittle fracturing associated with the development of pseudotachylyte-bearing faults and tension crack filling veins high angle to cleavage. These four phases can be explained as follows.During the inter-seismic period, an extensionally stable taper was maintained in the inner wedge of the accretionary prism by dominant vertical loading (sigma 1), in combination with a lesser amount of horizontal compression (sigma 2) related to the locking of the mega-thrust. Elastic strain energy in the hanging wall of the inner wedge was co-seismically released by slip on the mega-thrust and horizontal shortening in the outer wedge associated with dynamic ductile weakening of the fault plane. This sudden release of elastic strain caused brittle fracturing with sigma 1 at a high angle to the shear surface of the Nobeoka Thrust, most of the displacement resulting from deformation of the footwall. (C) 2013 Elsevier Ltd. All rights reserved.

    DOI: 10.1016/j.jsg.2013.03.015

    Web of Science

    researchmap

  • Importance of mechanochemical effects on fault slip behavior during earthquakes 査読

    Tetsuro Hirono, Wataru Tanikawa, Go Honda, Jun Kameda, Jun-ichi Fukuda, Tsuyoshi Ishikawa

    GEOPHYSICAL RESEARCH LETTERS   40 ( 12 )   2988 - 2992   2013年6月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:AMER GEOPHYSICAL UNION  

    Recent analyses of natural faults and laboratory rock friction experiments have revealed that physical transformations and chemical reactions of minerals and fluids occur in faults during earthquakes. However, exactly how these physicochemical processes affect fault weakening and earthquake energetics is not well understood. We present quantitative experimental evidence of mechanochemical changes in a clay mineral (illite) during frictional slip and evaluate the effect of those changes on slip behavior. Friction distorts the crystal structure of illite and dramatically decreases the activation energy (E-a) of the dehydroxylation reaction. Numerical modeling shows that the lower E-a allows the dehydroxylation to occur at relatively low temperatures (200-300 degrees C), which in turn drastically reduces fault strength by pressurization of released water from the mineral. Thus, dynamic thermo-chemo-mechanical processes can strongly affect earthquake instability, especially along clay-rich faults such as those in the shallow part of subduction zone plate boundaries.

    DOI: 10.1002/grl.50609

    Web of Science

    researchmap

  • Geological and frictional aspects of very-low-frequency earthquakes in an accretionary prism 査読

    Tsubasa Saito, Kohtaro Ujiie, Akito Tsutsumi, Jun Kameda, Bunichiro Shibazaki

    Geophysical Research Letters   40 ( 4 )   703 - 708   2013年2月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:Blackwell Publishing Ltd  

    Very-low-frequency earthquakes (VLFE) occur within accretionary prisms and near subduction plate boundaries at slip rates of 0.05-2 mm/s. However, the geological and frictional aspects of VLFE remain poorly understood. The thrusts in the Shimanto accretionary complex exhumed from source depths of VLFE are composed of quartz-rich fault rocks with or without clay foliations. We examined the frictional velocity dependence of thrust materials. At slip rates of 0.0028-0.28 mm/s, the powder sample from non-foliated fault rock shows velocity-weakening behavior, while that from foliated fault rock exhibits velocity-strengthening behavior. Both samples show velocity-strengthening behavior at slip rates of 0.28-2.8 mm/s. Microstructural analysis reveals that the velocity-weakening sample shows a shear localization, while the velocity-strengthening sample is marked by clay foliations oblique and parallel to shear zone boundaries. Our results imply that frictional instability generates along quartz-rich fault rock but slip becomes stable at higher slip rates, regardless of mineral composition. This is favorable for the occurrence of VLFE in subduction zones. Key Points Quartz-rich fault rock exhibits velocity-weakening behavior Quartz-rich fault rock is not unusual in accretionary prisms Frictional properties of thrust materials may explain the occurrence of VLFE ©2013. American Geophysical Union. All Rights Reserved.

    DOI: 10.1002/grl.50175

    Web of Science

    Scopus

    researchmap

  • Stress state in the largest displacement area of the 2011 Tohoku-Oki earthquake 査読

    Weiren Lin, Marianne Conin, J. Casey Moore, Frederick M. Chester, Yasuyuki Nakamura, James J. Mori, Louise Anderson, Emily E. Brodsky, Nobuhisa Eguchi, Becky Cook, Tamara Jeppson, Monica Wolfson-Schwehr, Yoshinori Sanada, Saneatsu Saito, Yukari Kido, Takehiro Hirose, Jan H. Behrmann, Matt Ikari, Kohtaro Ujiie, Christie Rowe, James Kirkpatrick, Santanu Bose, Christine Regalla, Francesca Remitti, Virginia Toy, Patrick Fulton, Toshiaki Mishima, Tao Yang, Tianhaozhe Sun, Tsuyoshi Ishikawa, James Sample, Ken Takai, Jun Kameda, Sean Toczko, Lena Maeda, Shuichi Kodaira, Ryota Hino, Demian Saffer

    Science   339 ( 6120 )   687 - 690   2013年2月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    The 2011 moment magnitude 9.0 Tohoku-Oki earthquake produced a maximum coseismic slip of more than 50 meters near the Japan trench, which could result in a completely reduced stress state in the region. We tested this hypothesis by determining the in situ stress state of the frontal prism from boreholes drilled by the Integrated Ocean Drilling Program approximately 1 year after the earthquake and by inferring the pre-earthquake stress state. On the basis of the horizontal stress orientations and magnitudes estimated from borehole breakouts and the increase in coseismic displacement during propagation of the rupture to the trench axis, in situ horizontal stress decreased during the earthquake. The stress change suggests an active slip of the frontal plate interface, which is consistent with coseismic fault weakening and a nearly total stress drop.

    DOI: 10.1126/science.1229379

    Scopus

    researchmap

  • IODP expedition 334: An investigation of the sedimentary record, fluid flow and state of stress on top of the seismogenic zone of an erosive subduction margin 査読

    Paola Vannucchi, Kohtaro Ujiie, Nicole Stroncik, Alberto Malinverno, Ivonne Arroyo, Udo Barckhausen, Marianne J. Conin, Susan Murr Foley, Michael J. Formolo, Robert N. Harris, Arnauld Heuret, Gary J Huftile, Jun Kameda, Gil Young Kim, Steffen O. Kutterolf, Amanda J. Martino, Gillian A. McCay, Marianne Nuzzo, Ken'ichi Ohkushi, Saneatsu Saito, Peter B. Sak, Evan A. Solomon, Michael Stipp, Marta E. Torres, Akito Tsutsumi, Masaoki Uno, Yoichi Usui, Yatheesh Vadakkeyakath, Yuzuru Yamamoto, Xixi Zhao, Junjiang Zhu, Jenifer Saltman

    Scientific Drilling   15 ( 15 )   23 - 30   2013年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    The Costa Rica Seismogenesis Project (CRISP) is an experiment to understand the processes that control nucleation and seismic rupture of large earthquakes at erosional subduction zones. Integrated Ocean Drililng Program (IODP) Expedition 334 by R/V JOIDES Resolution is the first step toward deep drilling through the aseismic and seismic plate boundary at the Costa Rica subduction zone offshore the Osa Peninsula where the Cocos Ridge is subducting beneath the Caribbean plate. Drilling operations included logging while drilling (LWD) at two slope sites (Sites U1378 and U1379) and coring at three slope sites (Sites U1378-1380) and at one site on the Cocos plate (Site U1381). For the first time the lithology, stratigraphy, and age of the slope and incoming sediments as well as the petrology of the subducting Cocos Ridge have been characterized at this margin. The slope sites recorded a high sediment accumulation rate of 160-1035m m.y.-1 possibly caused by on-land uplift triggered by the subduction of the Cocos Ridge. The geochemical data as well as the in situ temperature data obtained at the slope sites suggest that fluids are transported from greater depths. The geochemical profiles at Site U1381 reflect diffusional communication of a fluid with seawater-like chemistry and the igneous basement of the Cocos plate (Solomon et al., 2011
    Vannucchi et al., 2012a). The present-day in situ stress orientation determined by borehole breakouts at Site U1378 in the middle slope and Site U1379 in the upper slope shows a marked change in stress state within ~12 km along the CRISP transect
    that may correspond to a change from compression (middle slope) to extension (upper slope).

    DOI: 10.2204/iodp.sd.15.03.2013

    Scopus

    researchmap

  • Tectonic melange as fault rock of subduction plate boundary 査読

    Gaku Kimura, Asuka Yamaguchi, Megumi Hojo, Yujin Kitamura, Jun Kameda, Kohtaro Ujiie, Yohei Hamada, Mari Hamahashi, Shoko Hina

    TECTONOPHYSICS   568   25 - 38   2012年9月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ELSEVIER  

    An assemblage of quantitative data sets is examined to evaluate tectonic melange as a plate boundary fault rocks in subduction zone. The research object is the latest Cretaceous Mugi melange in the Shimanto Belt, southwest Japan. Systematic age younging from pelagic to terrigenous through hemipelagic sediments is well-documented even though original stratigraphy is disrupted. Systematic shear fabric consistent with ancient plate convergence is reconstructed. The melange was formed at temperatures of similar to 130-200 degrees C by cataclastic comminution of sandstone layers accompanied by tensile cracking, and plastic deformation and the dehydration of clayey shale matrix, with subsequent peeling off and underplating of the oceanic basement.The temperature setting for the Mugi melange indicates around the up-dip limit of the seismogenic zone, therefore includes various fault rocks suggestive of earthquake fault; pseudotachylyte, fluidized ultracataclasite with heating evidence, amorphous silica and so on. These suggest that fluid induced lubrication was dominated. Localized cataclastic shear, which is a candidate of small earthquake or very low frequency earthquake, is also recognized especially in sandstone blocks dominated portion in melange. These observations are consistent with the melange being a fault rock along the plate boundary that records various types of earthquakes in a subduction zone. The quantitative examination of the Mugi melange suggests several criteria to define the tectonic melange of the plate boundary fault in subduction zone from other melanges in orogenic belt. (c) 2011 Elsevier B.V. All rights reserved.

    DOI: 10.1016/j.tecto.2011.08.025

    Web of Science

    researchmap

  • Runaway slip to the trench due to rupture of highly pressurized megathrust beneath the middle trench slope: The tsunamigenesis of the 2011 Tohoku earthquake off the east coast of northern Japan 査読

    Gaku Kimura, Shoko Hina, Yohei Hamada, Jun Kameda, Takeshi Tsuji, Masataka Kinoshita, Asuka Yamaguchi

    EARTH AND PLANETARY SCIENCE LETTERS   339   32 - 45   2012年7月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ELSEVIER  

    The gigantic 2011, March 11 Mw 9 Tohoku earthquake is examined from the viewpoint of the pre-seismic forearc structure, the seismic reflection properties of a megathrust around the usual up-dip limit of the seismogenic zone, the thermal state of a shallow subduction zone, and the dehydration of underthrust sediments.At the Japan Trench the Pacific Plate is subducting westward beneath northeast Japan at a dip angle of 4.6 degrees. The middle and lower slopes of the landward side dip eastward at angles of similar to 2.5 degrees and similar to 8.0 degrees, respectively. The forearc prism beneath the middle and lower slopes is inferred to be in extensionally and compressively critical states, respectively, based on the presence of clear internal deformation features and on the occurrence of aftershock earthquakes. The rapid uplift of the forearc that caused the 2011 Tohoku tsunami may have been associated with this internal deformation of the prism. The critical state of the prism indicates that the effective basal friction (mu(b)') of the plate boundary megathrust is <0.03 for the middle prism and >0.08 for the lower prism.The megathrust, especially under the middle slope, is characterized by a prominent reflector with negative polarity. One of multiple possible explanations is that the megathrust hosts highly pressurized fluids. Underthrust sediments in this part of the Japan Trench are dominated by pelagic and siliceous vitric diatomaceous silt with clay. The dehydration kinetics of opal-A to quartz, the clay transformation of smectite-illite, and the thermal structure of the Japan Trench suggest that maximum dehydration of the sediments would take place at 50-60 km horizontally from the deformation front, where the temperature along the megathrust is 100-120 degrees C. The zone of maximum dehydration coincides with the prominent seismic reflector that has negative polarity. We hypothesize a possible free slip along this portion of the megathrust during the 2011 Tohoku earthquake, caused by anomalously high fluid pressure resulting from fluid accumulation over centuries. (C) 2012 Elsevier B.V. All rights reserved.

    DOI: 10.1016/j.epsl.2012.04.002

    Web of Science

    researchmap

  • Silica diagenesis and its effect on interplate seismicity in cold subduction zones 査読

    Jun Kameda, Shoko Hina, Kyoko Kobayashi, Asuka Yamaguchi, Yohei Hamada, Yuzuru Yamamoto, Mari Hamahashi, Gaku Kimura

    EARTH AND PLANETARY SCIENCE LETTERS   317   136 - 144   2012年2月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ELSEVIER  

    The diagenesis and deformation processes of ribbon cherts embedded in a Jurassic accretionary complex, central Japan, were investigated in detail to gain a better understanding of the mechanical behavior of the plate boundary at depth in cold subduction zones. The analyzed cherts record two stages of deformation: (1) map-to outcrop-scale ductile folding, and (2) subsequent brittle faulting. The ductile deformation was facilitated by silica dehydration precipitation, and is represented by multiple phases of vein networks. The folds are cut by brittle faults, indicating lithification and the concurrent mechanical transition from ductile to brittle behavior. Slip zones along the faults are typically filled with brecciated chert in a chlorite matrix. Geothermometry analysis of the matrix chlorite suggests that faulting occurred following the completion of opal-CT to quartz transition reaction. This is also confirmed by the kinetic simulation of silica conversion reactions. The results suggest that ductile deformation of thick pelagic deposits with abundant fluids results in an aseismic plate boundary, whereas chemical diagenesis of the deposits, producing crystalline cherts, results in interplate coupling in cold subduction zones such as the Japan Trench. (C) 2011 Elsevier B.V. All rights reserved.

    DOI: 10.1016/j.epsl.2011.11.041

    Web of Science

    researchmap

  • A new source of water in seismogenic subduction zones 査読

    Jun Kameda, Asuka Yamaguchi, Saneatsu Saito, Hiroshi Sakuma, Katsuyuki Kawamura, Gaku Kimura

    GEOPHYSICAL RESEARCH LETTERS   38   2011年11月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:AMER GEOPHYSICAL UNION  

    Seismogenic plate-boundary faults at accretionary margins (e.g., the Nankai margin, southwest Japan) may occur where the uppermost part of subducting oceanic crust, composed of basaltic rocks, is in contact with the overriding plate of a lithified accretionary prism. The plate-boundary faults in ancient accretionary complexes typically record high-velocity slip under fluid-rich conditions. Although previous studies have emphasized the mechanical significance of fluids in terms of dynamic slip-weakening, the source of fluid in seismogenic subduction zones remains poorly constrained. In this work, we focus on the hydrous smectite in the uppermost oceanic crust, an alteration product of intact basalt before arrival at the trench axis. A comparison between (1) new mineralogical data on basalt drillcore recovered by Integrated Ocean Drilling Program (IODP) Expedition 322 at site C0012, a reference site for subduction input to the Nankai Trough, and (2) mineralogical data on basalt within ancient oceanic crust embedded in a fossil accretionary complex of the Shimanto Belt, southwest Japan, suggests that progressive smectite-chlorite conversion would liberate bound fluids at a rate of 0.34 to 0.65 x 10(-14) s(-1) along the plate interface. This rate of fluid production appears to be more than an order of magnitude greater than that from other possible sources, including from overlying sediments via smectite-illite conversion and the expulsion of pore fluids, and may facilitate seismic slip along plate-boundary faults. Citation: Kameda, J., A. Yamaguchi, S. Saito, H. Sakuma, K. Kawamura, and G. Kimura (2011), A new source of water in seismogenic subduction zones, Geophys. Res. Lett., 38, L22306, doi:10.1029/2011GL048883.

    DOI: 10.1029/2011GL048883

    Web of Science

    researchmap

  • Progressive illitization in fault gouge caused by seismic slip propagation along a megasplay fault in the Nankai Trough 査読

    Asuka Yamaguchi, Arito Sakaguchi, Tatsuhiko Sakamoto, Koichi Iijima, Jun Kameda, Gaku Kimura, Kohtaro Ujiie, Frederick M. Chester, Olivier Fabbri, David Goldsby, Akito Tsutsumi, Chun-Feng Li, Daniel Curewitz

    GEOLOGY   39 ( 11 )   995 - 998   2011年11月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:GEOLOGICAL SOC AMER, INC  

    The question of whether coseismic ruptures along megasplay faults in accretionary prisms (i.e., large landward-dipping thrust faults branching from the plate boundary) reach the seafloor is critical for assessing the risk of tsunami disaster. However, samples from active megasplay faults have not previously been available. Here we present geochemical and mineralogical data of megasplay fault samples obtained from the shallow (&lt;300 m below seafloor) portion of the megasplay fault that coincides with the rupture area of the A. D. 1944 Tonankai earthquake in the Nankai Trough. The megasplay fault zone is characterized by localized shear zones of brecciated host rocks. A prominent slip zone, here termed "dark gouge," was discovered within one of the shear zones. Compared to the surrounding breccias, the dark gouge is chemically enriched in Al and K, and depleted in Ca and Sr. It is also characterized by higher illite content in illite-smectite mixed-layer clays. These chemical and mineralogical features may reflect a transformation in clay mineralogy caused by frictional heating, and suggest that the seismic slip can propagate to very shallow levels along megasplay fault systems.

    DOI: 10.1130/G32038.1

    Web of Science

    researchmap

  • Smectite to chlorite conversion by frictional heating along a subduction thrust 査読

    Jun Kameda, Kohtaro Ujiie, Asuka Yamaguchi, Gaku Kimura

    EARTH AND PLANETARY SCIENCE LETTERS   305 ( 1-2 )   161 - 170   2011年5月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ELSEVIER SCIENCE BV  

    An ancient subduction thrust, developed at the top of oceanic basaltic crust, is exposed in the Shimanto accretionary complex of eastern Shikoku, southwest Japan. The fault zone structure indicates that slip was localized along a few centimeters-thick layer in which fluidization of comminuted material is recorded. To identify possible clay mineral reactions during frictional heating along subduction thrusts, we examined the clay mineralogy of the basalt-derived fault zone rocks, including ultracataclasite, altered basalt, foliated cataclasite, and massive basalt. All samples include chlorite, mixed-layer chlorite/smectite (C/S), and corrensite. Among the samples, the highest chlorite content in the C/S is found in the ultracataclasite. The significant chloritization in the ultracataclasite is unlikely to reflect hydrothermal alteration and regional very-low-grade metamorphism during subduction down to seismogenic depths; instead, it is interpreted to have resulted from frictional heating associated with localized slip. Based on chlorite geothermometry and the presence of small quantities of corrensite, we estimate the temperatures during this frictional heating to have been in the range of 185-260 degrees C, which is 35-130 degrees C higher than the ambient temperature. This difference of 35-130 degrees C is consistent with a temperature rise of 50-150 degrees C indicated by the stretching of fluid inclusions in calcite. Therefore, the crystallographic and chemical properties of C/S are potentially useful in detecting small temperature rises associated with frictional heating, and the method could be widely applicable to C/S-bearing faults. (C) 2011 Elsevier B.V. All rights reserved.

    DOI: 10.1016/j.epsl.2011.02.051

    Web of Science

    researchmap

  • Low-grade metamorphism around the down-dip limit of seismogenic subduction zones: Example from an ancient accretionary complex in the Shimanto Belt, Japan 査読

    Jun Kameda, Hugues Raimbourg, Toshihiro Kogure, Gaku Kimura

    TECTONOPHYSICS   502 ( 3-4 )   383 - 392   2011年4月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ELSEVIER SCIENCE BV  

    Reactions involving clay minerals during low-grade metamorphism at the depth of an ancient accretionary complex in the Shimanto Belt, Kyushu, Japan, were studied by integrated transmission electron microscopy-energy dispersive X-ray spectroscopy and X-ray diffraction analyses of the bulk rock and clay fraction. The analyzed metasediment (the Kitagawa unit) contain an incipient sub-horizontal slaty cleavage. Illite crystallinity data and mica b dimensions indicate that the conditions of metamorphic deformation were anchizone-epizone grade and intermediate pressure. Cleavage formation was linked to two reactions involving clay minerals: (1) the recrystallization of 1M-dominant matrix mica, inherited from the original sedimentary fabric, into thick, defect-free 2M(1) packets along cleavage planes; and (2) the formation of chlorite from 7 angstrom berthierine. Balanced equations among the clay phases, based on compositional data and their relative abundance, suggest that the decomposition of matrix mica resulted in the formation of paragenetic mica and chlorite along the cleavage planes, without significant elemental outflux. Although a modal increase in phyllosilicates is not indicated by the data, the growth of chlorite and mica along cleavage planes may have a large influence on the rheological properties of a decollement and may be related to the occurrence of the seismic-aseismic transition at similar to 350 degrees C. (C) 2011 Elsevier B.V. All rights reserved.

    DOI: 10.1016/j.tecto.2011.02.010

    Web of Science

    researchmap

  • MINERALOGICAL CHARACTERIZATION OF ASIAN DUST COLLECTED IN FUKUOKA, SOUTHWEST JAPAN

    WATANABE KATSUAKI, SEKIYA MARIKO, KAMEDA JUN, WADA SHIN-ICHIRO, KOGURE TOSHIHIRO

    Clay Sci.   15 ( 1 )   43 - 51   2011年

     詳細を見る

    記述言語:英語   出版者・発行元:一般社団法人 日本粘土学会  

    Mineralogy of Asian dust collected in Fukuoka, Southwest Japan, was investigated using X-ray diffraction (XRD) and scanning/transmission electron microscopy (SEM/TEM) in detail. The dust consisted of only silicates; quartz, albite, orthoclase, amphibole and phyllosilicates (muscovite/illite, biotite, chlorite, kaolin group minerals and smectite). This mineral composition for silicates is very close to that of a certified reference specimen for Asian dust (CJ-1) which was collected from the loess plateau in China. However, carbonate minerals abundant in CJ-1 are missing in Fukuoka dust. Probably the carbonate and other water-soluble minerals were dissolved by rain or during sample collection using water. Observation and X-ray chemical analysis in SEM revealed their morphologies and chemical compositions. Amphibole, biotite and chlorite are major Fe-bearing minerals in the dust. Among them, fine chlorite particles may be a good Fe-supplier for microorganism living in the shallow area of the ocean.

    DOI: 10.11362/jcssjclayscience.15.1_43

    CiNii Article

    CiNii Books

    researchmap

  • Reproduction of thermal pressurization and fluidization of clay-rich fault gouges by high-velocity friction experiments and implications for seismic slip in natural faults 査読

    Kohtaro Ujiie, Akito Tsutsumi, Jun Kameda

    Geological Society Special Publication   359 ( 1 )   267 - 285   2011年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    We examine the frictional properties and microstructures of clay-rich fault gouges subjected to thermal pressurization and fluidization, generated in high-velocity friction experiments under dry and wet conditions. In the dry tests, slip weakening occurs by thermal pressurization, which is marked by a fault-gouge expansion associated with a water-phase transition from liquid to vapour. The water is derived from dehydration of clay minerals by frictional heating. The resulting microstructure in the gouge layer is a random distribution of spherical clay-clast aggregates in the matrix, and mixing of different gouge constituents without shear surfaces. In the wet tests, slip weakening is caused by pore-fluid pressurization resulting from shear-enhanced compaction of the water-saturated gouge and frictional heating. Compared to the dry tests, the wet tests show smaller dynamic stress drops and slip weakening distance. The steady-state shear stress in the wet tests is almost independent of normal stress, suggesting a fluid-like behaviour of the fault gouge during high-velocity shearing. The microstructures after the wet tests show that the foliated zone is accompanied by grain-size segregation in the gouge layer. The grain-size segregation is attributed to the Brazil-nut effect resulting from the difference in dispersive pressure in the granular- fluid shear flow at high shear rates, indicating a fluidization of fault gouge. Our results obtained at seismic slip rates imply that the propagation of an earthquake rupture can be enhanced by fluid pressurization and frictional heat, potentially leaving characteristic microstructures resulting from water vaporization by frictional heating or flow sorting at high slip rates. © The Geological Society of London 2011.

    DOI: 10.1144/SP359.15

    Scopus

    researchmap

  • Smectite swelling in the Miura-Boso accretionary prism: Possible cause for incipient decollement zone formation 査読

    Jun Kameda, Yuzuru Yamamoto, Gaku Kimura

    TECTONOPHYSICS   494 ( 1-2 )   75 - 84   2010年10月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ELSEVIER SCIENCE BV  

    An analysis of the mineralogy of the Miura-Boso accretionary prism, which consists of off-scraped upper Miocene strata exposed on the southern parts of the Miura and Boso peninsulas in Central Japan, revealed homogeneous mineral composition throughout all levels of silt layers hosting deformation structures associated with sediment accretion. XRD analyses showed that the sediment consists of randomly ordered mixed layer illite-smectite (I-S) with low illite content (&gt;40 wt.%), quartz (30 wt.%), illite (10-20 wt.%), plagioclase (10 wt.%), kaolinite (+ chlorite) (5 wt.%), and calcite (0-10 wt.%). The observed mineralogical assemblage indicates that location of the decollement formation was not constrained by mechanical heterogeneities associated with mineralogical variations, but was controlled by spatial variations in effective pressure. Within the over-consolidated sediment located above the incipient decollement zone, the occurrence of abundant smectite with a shape-preferred orientation gave rise to smectite swelling, producing pressures in the order of similar to 3.0 MPa. The combined effect of high swelling pressure and high pore pressure resulted in an overpressured zone at the base of the over-consolidated zone, facilitating the development of a decollement zone within the prism. (C) 2010 Elsevier B.V. All rights reserved.

    DOI: 10.1016/j.tecto.2010.08.008

    Web of Science

    researchmap

  • Characterization of the multilayered shell of a limpet, Lottia kogamogai (Mollusca: Patellogastropoda), using SEM-EBSD and FIB-TEM techniques 査読

    Michio Suzuki, Jun Kameda, Takenori Sasaki, Kazuko Saruwatari, Hiromichi Nagasawa, Toshihiro Kogure

    JOURNAL OF STRUCTURAL BIOLOGY   171 ( 2 )   223 - 230   2010年8月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ACADEMIC PRESS INC ELSEVIER SCIENCE  

    The microstructure and its crystallographic aspect of the shell of a limpet, Lottia kogamogai, have been investigated, as the first step to clarify the mechanism of shell formation in limpet. The shell consists of five distinct layers stacked along the shell thickness direction. Transmission electron microscopy (TEM) with the focused ion beam (FIB) sample preparation technique was primarily adopted, as well as scanning electron microscopy (SEM) with electron back-scattered diffraction (EBSD). The five layers were termed as M + 3, M + 2, M + 1, M, M - 1 from the outside to the inside in previous works, where M means myostracum. The outmost M + 3 layer consists of calcite with a "mosaic" structure; granular submicron sub-grains with small-angle grain boundaries often accompanying dislocation arrays. M + 2 layer consists of flat prismatic aragonite crystals with a leaf-like cross section, stacked obliquely to the shell surface. It looks that the prismatic crystals are surrounded by organic sheets, forming a compartment structure. M + 1 and M 1 layers adopt a crossed lamellar structure consisting of aragonite flat prisms with rectangular cross section. M layer has a prismatic structure of aragonite perpendicular to the shell surface and with irregular shaped cross sections. Distinct organic sheets were not observed between the crystals in M + 1, M and M - 1 layers. The (1 1 0) twins are common in all aragonite M + 2, M + 1, M and M - 1 layers, with the twin boundaries parallel to the prisms. These results for the microstructure of each layer should be considered in the discussion of the formation mechanism of the limpet shell structure. (C) 2010 Elsevier Inc. All rights reserved.

    DOI: 10.1016/j.jsb.2010.04.008

    Web of Science

    researchmap

  • Microtexture of larval shell of oyster, Crassostrea nippona: A FIB-TEM study 査読

    Miki Kudo, Jun Kameda, Kazuko Saruwatari, Noriaki Ozaki, Keiju Okano, Hiromichi Nagasawa, Toshihiro Kogure

    JOURNAL OF STRUCTURAL BIOLOGY   169 ( 1 )   1 - 5   2010年1月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ACADEMIC PRESS INC ELSEVIER SCIENCE  

    The initial formation and subsequent development of larval shells in marine bivalve, Crassostrea nippona were investigated using the FIB-TEM technique. Fourteen hours after fertilization (the trochophore stage), larvae form an incipient shell of 100-150 nm thick with a columnar contrast. Selected-area electron diffraction analysis showed a single-crystal aragonite pattern with the c-axis perpendicular to the shell surface. Plan-view TEM analysis suggested that the shell contains high density of {110} twins, which are the origin of the columnar contrast in the cross-sectional images. 72 h after fertilization (the veliger stage), the shell grows up to 1.2-1.4 mu m thick accompanying an additional granular layer between the preexisting layer and embryo to form a distinctive two-layer structure. The granular layer is also composed of aragonite crystals sharing their c-axes perpendicular to the shell surface, but the crystals are arranged with a flexible rotation around the c-axes and not restricted solely to the {110} twin relation. No evidence to suggest the existence of amorphous calcium carbonate (ACC) was found through the observation. The well-regulated crystallographic properties found in the present sample imply initial shell formation probably via a direct deposition of crystalline aragonite. (C) 2009 Elsevier Inc. All rights reserved.

    DOI: 10.1016/j.jsb.2009.07.014

    Web of Science

    researchmap

  • 日本粘土学会参考試料の分析・評価

    宮脇 律郎, 佐野 貴司, 大橋 文彦, 鈴木 正哉, 小暮 敏博, 奥村 大河, 亀田 純, 梅染 卓也, 佐藤 努, 千野 大輔, 弘山 郁織, 山田 裕久, 田村 堅志, 森本 和也, 上原 誠一郎, 八田 珠郎

    粘土科学   48 ( 4 )   158 - 198   2010年

     詳細を見る

    記述言語:日本語   出版者・発行元:一般社団法人 日本粘土学会  

    DOI: 10.11362/jcssjnendokagaku.48.4_158

    CiNii Article

    CiNii Books

    researchmap

  • THE OCCURRENCE AND STRUCTURE OF VERMIFORM CHLORITE

    KAMEDA JUN, OKAMOTO ATSUSHI, MIKOUCHI TAKASHI, KITAGAWA RYUJI, KOGURE TOSHIHIRO

    Clay Sci.   14 ( 4 )   155 - 161   2010年

     詳細を見る

    記述言語:英語   出版者・発行元:一般社団法人 日本粘土学会  

    To understand the origin of its unique morphology, the structure of vermiform chlorite has been investigated. Two chlorite specimens (magnesian chamosite) were analyzed: vermicular aggregates in quartz-feldspar veins in a pelitic schist, and those grown on a quartz single-crystal surface. Both specimens show very similar textures; they are composed of pseudohexagonal chlorite plates of several tens μm in lateral size and several hundreds nm in packet thickness, stacked to form long vermicular aggregates up to several hundreds μm. Chemical analyses indicated that the two specimens have similar compositions with ^&lt;IV&gt;Al 1.2〜1.3 per 4.0 sites and Fe/(Mg+Fe) ratio of 〜0.55. XRD and EBSD indicate IIbb semi-random stacking. HRTEM shows that the stacking is considerably disordered in terms both of the layer orientation and direction of the interlayer displacement. The vermicular morphology of chlorite is probably originated from a relatively faster spiral growth along the stacking in hydrothermal fluid.

    DOI: 10.11362/jcssjclayscience.14.4_155

    CiNii Article

    CiNii Books

    researchmap

  • Modification to the crystal structure of chlorite during early stages of its dissolution 査読

    Jun Kameda, Hirokazu Sugimori, Takashi Murakami

    PHYSICS AND CHEMISTRY OF MINERALS   36 ( 9 )   537 - 544   2009年10月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:SPRINGER  

    Early stage processes of Mg-rich chlorite (clinochlore) dissolution were examined, focusing especially on the structural modification at grain edges during dissolution. Focused ion beam transmission electron microscopy sample preparation was applied to crystals dissolved in a flow-through reaction system at pH 3.0 and 25A degrees C for 31 days. The obtained Si and Mg dissolution rates are -11.49 and -11.14 (logR, mol/(m(2)/s)), respectively, implying dissolution is non-stoichiometric. TEM-EDX analyses of dissolved samples reveal the development of 20-50-nm thick amorphous zone at an outermost rim with a chemical gradient of Mg, lower towards the solid surface, and Si enrichment in this amorphous zone. Crystalline material is partially interwoven with amorphous one at the interface between the amorphous and crystalline regions. These results indicate that the amorphous zone was produced by selective leaching of cations except for Si. Chlorite dissolution may proceed via the formation and thickening of leached layer as a by-product of release to solution of Si at slightly slower rate than Mg.

    DOI: 10.1007/s00269-009-0299-x

    Web of Science

    researchmap

  • STACKING FAULTS WITH 180 degrees LAYER ROTATION IN CELADONITE, AN Fe- AND Mg-RICH DIOCTAHEDRAL MICA 査読

    Toshihiro Kogure, Jun Kameda, Victor A. Drits

    CLAYS AND CLAY MINERALS   56 ( 6 )   612 - 621   2008年12月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:CLAY MINERALS SOC  

    Stacking disorder in celadonite, a dioctahedral mica with Fe and Mg as major octahedral cations and which generally adopts the 1M stacking sequence, was investigated mainly by using transmission electron microscopy (TEM). The selected-area electron diffraction patterns with 0kl reflections along the [100] beam direction correspond to the 1M stacking but those along the [110], [1 (1) over bar0], [010], [310], and [3 (1) over bar0] directions are frequently streaked along the [001]* direction or contain extra spots from twinned domains. Three-dimensional stacking analyses using sets of two high-resolution TEM images along different directions of the same area of one crystal indicate that all stacking faults involve only 180 degrees layer rotations. These stacking faults produce greater peaks of 0kl reflections than expected in powder X-ray diffraction (XRD) patterns. Simulation of the XRD patterns indicated that 180 degrees layer rotations occur at &gt;10% of total interlayer regions in one celadonite specimen. The interlayer region of celadonite is characterized by a near-zero ditrigonal rotation angle, a small surface corrugation of the basal oxygen plane, and a small amount of Al substitution in the tetrahedral sheets. These features suggest that there is no preference for any of the six stacking angles around the interlayer region. The abundance of 180 degrees layer rotation rather than +/- 60 degrees and +/- 120 degrees in the present specimens may be related to their ribbon-like morphologies elongated along the a axis.

    DOI: 10.1346/CCMN.2008.0560602

    Web of Science

    researchmap

  • Chiral bead-like trimer of tris(2,4-pentanedionato)ruthenium(III) 査読

    Hisako Sato, Jun Kameda, Yutaka Fukuda, Masa-aki Haga, Akihiko Yamagishi

    CHEMISTRY LETTERS   37 ( 7 )   716 - 717   2008年7月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:CHEMICAL SOC JAPAN  

    A chiral tri-nuclear metal complex, Delta Delta Delta- or Lambda Lambda Lambda-[Ru(acac)(2)(taet)Ru(acac)(taet)Ru(acac)(2)] (acac = acetylacetonato and taet = tetraacetylethanato), was prepared and its monolayer behavior was investigated, leading to the conclusion that the bead-like character of the trimer was an essential factor in achieving stable two-dimensional molecular packing.

    DOI: 10.1246/cl.2008.716

    Web of Science

    researchmap

  • Textures and polytypes in vermiform kaolins diagenetically formed in a sandstone reservoir: a FIB-TEM investigation 査読

    Jun Kameda, Kazuko Saruwatari, Daniel Beaufort, Toshihiro Kogure

    EUROPEAN JOURNAL OF MINERALOGY   20 ( 2 )   199 - 204   2008年3月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:E SCHWEIZERBARTSCHE VERLAGS  

    Focused ion beam (FIB) sample preparation was applied to vermiform kaolin minerals to investigate by TEM the morphological evolution and mechanisms of kaolinite-to-dickite transformation during burial diagenesis. A core sample of a K-feldspar bearing arkosic sandstone, collected from the Brent Group sediments of the Froy hydrocarbon reservoir, Norwegian continental shelf, North Sea, was studied. Two types of vermiform aggregates were analyzed: 1) porous aggregates of fine lamellar crystals or intercalations of blocky and lamellar crystals, and 2) aggregates of densely packed hexagonal crystals. Electron diffraction (ED) revealed that aggregates of the first type are composed of pure one-layer kaolinite, whereas those of the second type consist of pure two-layer dickite. The two polytypes never coexist within the same aggregate. Furthermore, ED patterns of kaolinite and dickite are almost streak free, indicating a very low density of stacking faults. These observations suggest that the kaolinite-to-dickite transition in the pores of sandstone reservoir during burial diagenesis takes place by a dissolution-precipitation process rather than by a solid-state process. Blocky kaolinite, grown epitaxially on the (001) surface of muscovite, was also found in the specimen.

    DOI: 10.1127/0935-1221/2008/0020-1806

    Web of Science

    researchmap

  • High-resolution TEM and XRD simulation of stacking disorder in 2 : 1 phyllosilicates 査読

    Toshihiro Kogure, Jun Kameda

    ZEITSCHRIFT FUR KRISTALLOGRAPHIE   223 ( 1-2 )   69 - 75   2008年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:OLDENBOURG VERLAG  

    Stacking disorder is a common phenomenon in phyllosilicates but its nature is difficult to be deduced using conventional diffraction techniques. In contrast, recent investigations using high-resolution transmission electron microscopy (HRTEM) have elucidated the structure of stacking disorder in various phyllosilicates, by directly observing individual layers and stacking sequences. Furthermore, simulations of X-ray or electron diffraction patterns using the information from the HRTEM results can complement the limited analysis area in TEM and quantify the density of the stacking disorder.
    Although the bonding between adjacent layers is similar, there is a significant difference in the stacking disorder between two counterparts of dioctahedral and trioctahedral 2: 1 phyllosilicates: pyrophyllite vs. talc and sudoite vs. trioctahedral chlorite. In pyrophyllite and sudoite, stacking disorder is caused mainly by two alternatives of the lateral displacement directions between the two tetrahedral sheets across the interlayer region. On the other hand, rotation of 2: 1 layer is also an origin of the stacking disorder in talc and trioctahedral chlorite. This difference is explained by the corrugation of basal oxygen planes on the dioctahedral 2: 1 layer formed by the tetrahedral tilting to enlarge trans-vacant octahedral sites.

    DOI: 10.1524/zkri.2008.0004

    Web of Science

    researchmap

  • Morphological analyses of minute crystals by using stereo-photogrammetric scanning electron microscopy and electron back-scattered diffraction 査読

    Jun Kameda, Ryoichi Inoguchi, David J. Prior, Toshihiro Kogure

    JOURNAL OF MICROSCOPY-OXFORD   228 ( 3 )   358 - 365   2007年12月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:BLACKWELL PUBLISHING  

    We present a new method for the morphological analyses of minute faceted crystals by combining stereo-photogrammetric analysis of scanning electron microscope images and electron back-scattered diffraction. Two scanning electron microscope images of the same crystal, recorded at different tilt angles of the specimen stage, are used to determine the orientations of crystal edges in a specimen-fixed coordinate system. The edge orientations are converted to the indices [uvw] in the crystal system using the crystal orientation determined by electron back-scattered diffraction analysis. The Miller indices of crystal facets are derived from the indices of the edges surrounding the facets. The method is applicable to very small crystal facets. The angular error, as derived from tests using a calcite crystal of known morphology, is a few degrees.
    To demonstrate the applicability of the method, the morphology of boehmite (gamma-AlOOH) precipitated from solution during the dissolution of anorthite was analyzed. The micrometre-sized boehmite crystals are surrounded by two {010} basal facets and eight equivalent side facets that can be indexed equally well as {323}, {434} or {545}. We suggest that these side facets are in fact {111}, the morphology having been modified slightly (by a few degrees) by a small extension associated with opening along (010) microcleavage planes. Tiny {140} facets are also commonly observed.

    DOI: 10.1111/j.1365-2818.2007.01854.x

    Web of Science

    researchmap

  • XRD and HRTEM analyses of stacking structures in sudoite, di-trioctahedral chlorite 査読

    Jun Kameda, Ritsuro Miyawaki, Ryuji Kitagawa, Toshihiro Kogure

    AMERICAN MINERALOGIST   92 ( 10 )   1586 - 1592   2007年10月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:MINERALOGICAL SOC AMER  

    The stacking structures of sudoite, di-trioctahedral chlorite from two different localities are investigated by powder X-ray diffraction (XRD) and high-resolution transmission electron microscopy (HRTEM). XRD analyses using a Gandolfi camera revealed that the structures of both specimens are similar, corresponding to a one-layer IIbb-4 (1A) polytype. HRTEM observations indicate that the stacking sequence is characterized by a largely uniform intralayer shift of a/3 in the -X-1 direction (Xi represent the directions along the pseudohexagonal axes) and by an interlayer displacement of similar magnitude in either the -X-2 or -X-3 direction. Stacking disorder is primarily caused by the mixing of interlayer displacements in the two directions. This disorder is more common in the lath-shaped crystalline specimen from Berezovsk, Russia than in the fine platy crystalline specimen from Ottre, Belgium. DIFFaX simulations of the powder XRD patterns for this stacking model reproduced the observed features well for both specimens. The stacking configuration of these sudoite specimens is considered to be controlled by the corrugation of basal oxygen planes in the 2:1 layer and the corresponding deformation in the brucite-like interlayer sheet.

    DOI: 10.2138/am.2007.2410

    Web of Science

    researchmap

  • Polytype and morphological analyses of gumbelite, a fibrous Mg-rich illite 査読

    Jun Kameda, Ritsuro Miyawaki, Victor A. Drits, Toshihiro Kogure

    CLAYS AND CLAY MINERALS   55 ( 5 )   453 - 466   2007年10月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:CLAY MINERALS SOC  

    Polytypism in gumbelite and its relationship to the fibrous or ribbon-like morphology exhibited by this Mg-rich illite were investigated by powder X-ray diffraction (XRD), electron back-scattered diffraction (EBSD) and transmission electron microscopy (TEM). Comparison between the XRD pattern from oriented fibers using a conventional powder diffractometer and a randomly oriented pattern using a Gandolfi camera suggested that 2M(2) is dominant but other polytypes belonging to subfamily A also exist, and that the fiber axis of gCimbelite is parallel to &lt; 1 10 &gt; in 2M(2), &lt; 1 10 &gt; in 2M(1), and &lt; 100 &gt; in 1M.TheEBSD analyses confirmed these crystallographic directions directly from individual crystals. Electron diffraction and high-resolution TEM showed that twinning and intergrowths of various polytypes including both subfamilies are common in a single crystal and that the two types of rotations [2n60 degrees and (2n+1)60 degrees] between adjacent layers are often randomly mixed at the monolayer level. The data suggest that high densities of twinning and intergrowths account for the origin of the fibrous morphology along &lt; 1 10 &gt; for 2M(1) and 2M(2) polytypes. Volume restriction in a confined vein space may also play a role.

    DOI: 10.1346/CCMN.2007.0550501

    Web of Science

    researchmap

  • Persistent phenomena in photocurrent of niobate nanosheets 査読

    Kentaro Okamoto, Hisako Sato, Kazuko Saruwatari, Kenji Tamura, Jun Kameda, Toshihiro Kogure, Yasushi Umemura, Akihiko Yamagishi

    JOURNAL OF PHYSICAL CHEMISTRY C   111 ( 34 )   12827 - 12833   2007年8月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:AMER CHEMICAL SOC  

    A thin film of trimethylammonium-exchanged perovskite-type niobate ((CH3)(3)NHSr2Nb3O10) was prepared by casting its exfoliated aqueous dispersion onto a glass substrate. The electric conductivity of a film (3-9 mu m thick) was measured in vacuum under the illumination of light (280 similar to 450 nm). Photocurrent raised and decayed slowly in the time range of 10(3) seconds in response to the on-and-off of an incident light. Atmospheric oxygen accelerated the decay rate of current in the dark. In the absence of oxygen, the decay curve obeyed the equation of stretched exponential relaxation (i(p) = i(p)(0) exp(-(t/tau)(beta)). From the dependence of the photocurrent on various parameters such as film thickness, light wavelength, and temperature, the observed persistent phenomena were interpreted according to the following mechanisms: (1) a free electron was photogenerated under the illumination of light most effectively when photon energy corresponded to the edge of a band gap transition; (2) the generated electrons were trapped at surface oxygen vacancies before they became conductive; and (3) a persistent current appeared through the multistep trapping-detrapping processes under the gradient of electric field. It was suggested that vacancies were produced by the elimination of lattice oxygen atoms as dianions during the acid treatment of original niobate (KSr2Nb3O10). As far as we know, the present finding is the first example of persistent photocurrents in inorganic thin films.

    DOI: 10.1021/jp073380k

    Web of Science

    researchmap

  • Novel 2 : 1 structure of phyllosilicates formed by annealing Fe3+, Mg-rich dioctahedral mica 査読

    Toshihiro Kogure, Jun Kameda, Victor A. Drits

    AMERICAN MINERALOGIST   92 ( 8-9 )   1531 - 1534   2007年8月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:MINERALOGICAL SOC AMER  

    A new modification of the 2 : 1 phyllosilicate layer has been discovered in annealed celaclonite, a Fe 31, Mg-rich dioctahedral mica. Plan-view diffraction patterns in TEM indicate a base-centered supercell with A = 3a and B = b, where a and b are the cell dimensions of the originat mica. Basic hOl reflections with h = 3n form an orthogonal lattice with one-layer periodicity, which is not expected for normal micas. The high-resolution TEM image along the (100) or related directions is similar to that expected from normal micas but the image along the (0 I 0) directions is completely different. From these images, it is concluded that the two tetrahedral sheets in a 2 : 1 layer are facing each other with no lateral a/3 stagger. In the proposed model that explains the high-resolution TEM images, two thirds of the spaces surrounded by two facing tetrahedral six-member rings accommodate three (Fe3+,Mg) cations and one third of the spaces are completely vacant. The (Fe3+,Mg) cations are coordinated by six or five oxygen atoms forming trigonal prisms or square pyramids, respectively.

    DOI: 10.2138/am.2007.2667

    Web of Science

    researchmap

  • Electron transfer through clay monolayer films fabricated by the Langmuir- Blodgett technique 査読

    Jun Yoshida, Kazuko Saruwatari, Jun Kameda, Hisako Sato, Akihiko Yamagishi, Laisheng Sun, Maria Corriea, Gilles Villemure

    LANGMUIR   22 ( 23 )   9591 - 9597   2006年11月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:AMER CHEMICAL SOC  

    Hybrid films composed of amphiphilic molecules and clay particles were constructed by the modified Langmuir-Blodgett (LB) method. Clays used were sodium montmorillonite (denoted as mont) and synthetic smectite containing Co(II) ions in the octahedral sites (denoted as Co). Two kinds of amphiphilic molecules were useds[Ru(dC(18)bpy)( phen)(2)](ClO4)(2) (dC(18)bpy)4,4'-dioctadecyl-2,2-bipyridyl and phen = 1,10-phenanthroline) (denoted as Ru) and octadecylammonium choloride (ODAH(+) Cl- or denoted as ODAH). Three kinds of hybrid films (denoted as Rumont, Ru-Co, and ODAH-Co films) were prepared by spreading an amphiphilic molecule onto an aqueous suspension of a clay. Atomic force microscopy (AFM) analyses of the films deposited on silicon wafers indicated that closely packed films were obtained at 20 ppm for all the above three cases. Cyclic voltammetry (CV) was measured on an ITO electrode modified with a hybrid film or a monolayer film of pure Ru(II) complex salt (denoted as Ru film). The Ru( II) complexes incorporated in the Ru-mont film lost their redox activity, indicating that montmorillonite layers acted as a barrier against electron transfer. In contrast, the same complexes in the Ru-Co film were electrochemically active with the simultaneous appearance of the redox peaks due to the Co(II)/Co(III) (or Co(II)/ Co(IV))couple. The results implied that electron transfer through cobalt clay layers was possible via mediation by Co( II) ions in a clay sheet. For an aqueous solution containing nitrite ions (NO2-) at pH 3.0, a large catalytic oxidation current was observed for both the electrodes modified with the Ru-mont and Ru-Co films. The results were interpreted in terms of the mechanisms that the charge separation of an incorporated Ru(II) complex took place to produce a pair of a Ru(III) complex and an electron and that the generated Ru(III) complex was reduced by a nitrite ion before it recombined with the electron.

    DOI: 10.1021/la061668f

    Web of Science

    researchmap

  • Dissolution of brucite on the (001) surface at neutral pH: In situ atomic force microscopy observations 査読

    Yuriko Kudoh, Jun Kameda, Toshihiro Kogure

    CLAYS AND CLAY MINERALS   54 ( 5 )   598 - 604   2006年10月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:CLAY MINERALS SOCIETY  

    The dissolution of brucite, Mg(OH)(2), on the (001) surface was investigated using in situ atomic force microscopy in solutions at near-neutral pH. Dissolution proceeded by the formation of crystallographically oriented triangular etch pits with monolayer step and expansion of the pits. The sides of the triangle are parallel to the [100], [110] and [010] directions of the brucite structure, and the orientation of lines from the center of the triangle to the three apices are along the [210], [(1) over bar 10] and [(12) over bar0] directions. This orientation may produce pit edges where OH groups coordinate to two Mg2+. Although triangular etch pits with monolayer depth formed mostly at random on the (001) surface, concentric pits penetrating several layers were also observed. Etch pits with spiral steps were rarely observed. Coalescence of the pits resulted in stranded terraces that diminished in size rapidly and formed a rounded irregular form. The step-retreat velocity around the triangular pit is 0.015-0.04 nm/s at pH 5-8. The retreat velocity around the stranded terraces was about three times more rapid than that around the triangular etch pits.

    DOI: 10.1346/CCMN.2006.0540506

    Web of Science

    researchmap

  • Stacking structure in disordered talc: Interpretation of its X-ray diffraction pattern by using pattern simulation and high-resolution transmission electron microscopy 査読

    Toshihiro Kogure, Jun Kameda, Tomoyuki Matsui, Ritsuro Miyawakiz

    AMERICAN MINERALOGIST   91 ( 8-9 )   1363 - 1370   2006年8月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:MINERALOGICAL SOC AMER  

    Stacking structure in disordered talc, Mg3Si4O10(OH)(2), has been investigated by using high-resolution transmission electron microscopy (HRTEM) and by comparison between experimental and simulated powder X-ray diffraction (XRD) patterns. The talc specimen investigated was massive aggregates of fine platy crystals from the Shirakashi mine, Nagasaki-Prefecture, Japan, formed from regional metamorphism. HRTEM observations revealed that the orientation of the 2:1 layer, which is described by the direction of the lateral shift of a/3 from the lower tetrahedral sheet to the upper tetrahedral sheet within the 2:1 layer (intralayer shift), is almost completely disordered. In contrast, lateral displacement between the adjacent tetrahedral sheets across the interlayer region (interlayer displacement) is relatively ordered. The interlayer displacement parallel to the intralayer shift in lower or upper 2:1 layers tends to be avoided.
    A Gandolfi camera was used to record XRD patterns from a small fragment of the aggregates, to avoid preferred orientation and artifacts in stacking sequence by grinding. XRD patterns were simulated using the DIFFaX program and compared with experimental patterns. The experimental pattern from hk = 02, 11, and 11 reciprocal lattice rows is explained by a mixture of the stacking sequence with almost random directions of intralayer shift and a small amount of 1A dominant stacking sequence. The peak profiles for the reflections indexed with 20l, 13l, or 13l are reproduced by considering their variance, and a slightly different interlayer displacement from that reported in talc-1A.

    DOI: 10.2138/am.2006.2196

    Web of Science

    researchmap

  • Stacking structures in pyrophyllite revealed by high-resolution transmission electron microscopy (HRTEM) 査読

    Toshihiro Kogure, Mayumi Jige, Jun Kameda, Akihiko Yamagishi, Ritsuro Miyawaki, Ryuji Kitagawa

    AMERICAN MINERALOGIST   91 ( 8-9 )   1293 - 1299   2006年8月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:MINERALOGICAL SOC AMER  

    Stacking structures in pyrophyllite, Al2Si4O10(OH)(2), were investigated mainly by using high-resolution transmission electron microscopy (HRTEM). The specimens examined were large lath-shaped crystals (Berosovska, Urals, Russia) and massive aggregates of fine platy crystals (Nohwa, southwest Korea). Both specimens showed powder X-ray diffraction (XRD) patterns similar to those reported previously as the 2M polytype. The common stacking sequence in the two specimens is not monoclinic with two-layer periodicity as previously reported, but a uniform orientation of the 2:1 layers and near complete disorder of two alternative directions of interlayer displacement, i.e., lateral displacement between the two tetrahedral sheets across an interlayer region. The directions of interlayer displacement are about +/- 2 pi/3 from that of the intralayer shift (lateral displacement between the two tetrahedral sheets within a 2:1 layer). Simulation of powder XRD patterns by this stacking model closely approximates the experimental pattern. Elongation of the lath-shaped Berosovska crystals corresponds to the direction of the intralayer shift, as seen in illite-1M.
    2:1 layers with different orientations, and interlayer displacement almost parallel to the intralayer shift, were occasionally observed as stacking faults. Such disorder occurs more frequently in the massive Nohwa specimen than in the Berosovska specimen. Sub-micrometer domains of the 2M stacking sequence with regular alternation of the two directions of interlayer displacement were found in the Nohwa specimen.

    DOI: 10.2138/am.2006.1997

    Web of Science

    researchmap

  • Surface roughness of alumina fragments caused by hypervelocity impact 査読

    T Kadono, J Kameda, K Saruwatari, H Tanaka, S Yamamoto, A Fujiwara

    PLANETARY AND SPACE SCIENCE   54 ( 2 )   212 - 215   2006年2月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:PERGAMON-ELSEVIER SCIENCE LTD  

    Hypervelocity impact experiments are carried out with alumina ceramic targets at impact velocities of 2-4 km/s. The fractal dimension (or roughness exponent) of fragment surfaces is estimated by two different methods (different length scales). One is a divider method (large scale) and the other is a gas-absorption one (small scale). The obtained fractal dimensions are different: similar to 2.2-2.4 for larger scale and similar to 2.5-2.7 for smaller scale. These values are regardless of the degree of fragmentation. (c) 2005 Elsevier Ltd. All rights reserved.

    DOI: 10.1016/j.pss.2005.09.002

    Web of Science

    researchmap

  • Morphological characteristics of ordered kaolinite: Investigation using electron back-scattered diffraction 査読

    J Kameda, A Yamagishi, T Kogure

    AMERICAN MINERALOGIST   90 ( 8-9 )   1462 - 1465   2005年8月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:MINERALOGICAL SOC AMER  

    Morphology of kaolinite crystals with high-crystallinity (Keokuk, Iowa) has been investigated by electron back-scattered diffraction (EBSD) and high-resolution scanning electron microscopy (SEM). EBSD patterns from the specimen generally correspond to those expected from ordered kaolinite. Elongated hexagonal crystals always show the a-axis parallel to the elongated direction. The side-facets of these crystals are in parallel to the c-axis, which is inclined by about 15 degrees from the normal to the basal plane. The Miller indices of the side-facets are exactly +/-(110), +/-(1 (1) over bar0), and +/-(0 10). A facet indexed as +/-(1 (3) over bar0) is developed in some crystals. These morphological characteristics must be reflected in the ordered stacking sequences (the position of the octahedral vacancy site and the direction of the interlayer shift) of the Keokuk kaolinite. Inversely, the crystallinity of individual kaolinite grains may be evaluated from their morphology in a SEM. The feasibility to discriminate the enantiomers in kaolinite using EBSD is also described.

    DOI: 10.2138/am.2005.1928

    Web of Science

    researchmap

  • Photoconductive properties of organic-inorganic hybrid films of layered perovskite-type niobate 査読

    K Saruwatari, H Sato, T Idei, J Kameda, A Yamagishi, A Takagaki, K Domen

    JOURNAL OF PHYSICAL CHEMISTRY B   109 ( 25 )   12410 - 12416   2005年6月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:AMER CHEMICAL SOC  

    A hybrid film of layered niobate and an organic amphiphile was prepared by the Langmuir-Blodgett (LB) method. Trimethylammonium-exchanged perovskite-type niobates ((CH3)(3)NHSr2Nb3O10) were exfoliative to form an aqueous suspension. A monolayer of octadecylamine was produced on such an aqueous dispersion as a template for a hybrid film. A hybrid film was transferred as a Y-type LB film onto a hydrophilic glass plate or an ITO substrate. The structure of a deposited film was investigated with X-ray diffraction (XRD), Fourier transform infrared (FT-IR), and atomic force microscopy (AFM) measurements, indicating a layer-by-layer structure with a single or double sheet of niobate as an inorganic composite. From the cyclic voltammogram on an ITO electrode modified with the Y-type 10 layered film, the lower edge of the conduction band of a niobate layer was determined to be - 0.6 V (vs Ag/AgCl). ac impedance and dc measurements were carried out on 1, 5, and 10-layered LB films (2 mm (electrode spacing) x 8 mm (width)) with aluminum electrodes. The freshly deposited samples behaved as an insulator under the illumination of 280 nm light (2.04 x 10(16) quanta s(-1)). Photoconductivities appeared, however, when they were preirradiated with a 150 W Xe lamp (ca. 2 x 10(18) quanta s(-1)) for 0.5-8.5 h. The process was denoted as photomodification. From the FT-IR and XRD results, it was deduced that the photomodification of LB films caused the decomposition of organic templates (octadecylammonium) accompanied by the collapse of layer-by-layer structures. dc analyses on the 5- and 10-layered films after photomodification also showed that they behaved as a photosemiconductor under UV light illumination.

    DOI: 10.1021/jp0505476

    Web of Science

    researchmap

  • Evidence for the role of organic layers in photoconductivity of organic/inorganic hybrid nanosheets as prepared by Langmuir-Blodgett methods 査読

    K Saruwatari, H Sato, J Kameda, A Yamagishi, K Domen

    CHEMICAL COMMUNICATIONS   ( 15 )   1999 - 2001   2005年4月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ROYAL SOC CHEMISTRY  

    By measuring the photoconductivity of hybrid LB films of exfoliative layered niobate and octadecylamine, it was evidenced that the film underwent a transition from an insulator to a photosemiconductor during photo-modification treatment by UV fight, which was rationalized in terms of the direct contact of inorganic nanosheets achieved by the elimination of organic layers.

    DOI: 10.1039/b419064e

    Web of Science

    researchmap

  • H-2 generation during dry grinding of kaolinite 査読

    J Kameda, K Saruwatari, H Tanaka

    JOURNAL OF COLLOID AND INTERFACE SCIENCE   275 ( 1 )   225 - 228   2004年7月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ACADEMIC PRESS INC ELSEVIER SCIENCE  

    H-2 generation during mechanochemical treatment of kaolinite by dry grinding was examined by X-ray diffraction analysis, Fourier transform infrared spectroscopy, and BET surface area measurement. The H-2 concentration in the mill pot, measured by gas chromatography, increased with grinding time up to a maximum concentration of 156 ppm (0.35 mumol) after 600 min. This H-2 generation is considered to occur as a result of three processes: (1) structural destruction characterized by the delamination and loss of hydroxyl groups as a result of dry grinding, (2) transformation of liberated hydroxyls into water molecules by mechanochemical effects such as prototropy, and (3) H-2 generation through reaction between surface water molecules and mechanoradicals created by the rupture of Si-O or Al-O-Si bonds. Although the surface area plateaued after 240 min grinding, the H-2 concentration continued to increase, indicating that surface mechanoradicals are created during this later grinding stage. Thus, H-2 generation can be used as an indicator of mechanoradical formation during mechanochemical treatment. (C) 2004 Elsevier Inc. All rights reserved.

    DOI: 10.1016/j.jcis.2004.02.014

    Web of Science

    researchmap

  • Generation of hydrogen ions and hydrogen gas in quartz-water crushing experiments: an example of chemical processes in active faults 査読

    K Saruwatari, J Kameda, H Tanaka

    PHYSICS AND CHEMISTRY OF MINERALS   31 ( 3 )   176 - 182   2004年4月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:SPRINGER-VERLAG  

    To understand the fundamental chemical processes of fluid-rock interaction during the pulverization of quartz grains in fault zones, quartz grains were crushed within pure water. The crushing experiments were performed batch style using a shaking apparatus. The crushing process induced a decrease in pH and an increase in hydrogen gas with increased shaking duration. The amount of hydrogen ions generated was five times larger than that of the hydrogen gas, which was consistent with the amount of Si radicals estimated from electron spin resonance measurements by Hochstrasser and Antonini (1972). This indicates that hydrogen gas was generated by consuming most of the Si radicals. The generation of hydrogen ions was most likely related to the presence of silanols on the newly formed mineral surface, implying a change of proton activities in the fluid after pulverization of quartz.

    DOI: 10.1007/s00269-004-0382-2

    Web of Science

    researchmap

  • Mechanisms of hydrogen generation during the mechanochemical treatment of biotite within D2O media 査読

    J Kameda, K Saruwatari, H Tanaka, F Tsunomori

    EARTH PLANETS AND SPACE   56 ( 12 )   1241 - 1245   2004年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:TERRA SCIENTIFIC PUBL CO  

    The mechanism of hydrogen generation during the mechanochemical treatment of biotite was examined by grinding experiments using a ball mil in H2O or D2O as a grinding media. From the linear relationship between the amount of generated hydrogen and the increase of the surface area of ground powders, the hydrogen productivity of biotite is estimated to be 0.036 mu mol/m, which agrees with the previous results in spite of the difference in the grinding conditions. D-2 analyses by a mass spectrometry indicate that the produced amount of D-2 accounts for only 10% of the total hydrogen and that more than 90% of hydrogen takes a form of a mixture of HD and H-2. The observed isotope distribution clearly indicates that hydroxyls within the crystal structure can be a major source for the generation of hydrogen. Hydrogen generation originated from hydroxyls may indicate the higher hydrogen productivity of phyllosilicates than those of quartz and alkali feldspar.

    DOI: 10.1186/BF03353346

    Web of Science

    researchmap

  • Hydrogen generation by wet grinding of quartz powders and its dependence on the pH and ionic strength of liquid media 査読

    J Kameda, K Saruwatari, H Tanaka

    BULLETIN OF THE CHEMICAL SOCIETY OF JAPAN   76 ( 11 )   2153 - 2154   2003年11月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:CHEMICAL SOC JAPAN  

    Hydrogen generation was investigated by grinding quartz powder in pH- and ionic strength-controlled liquid media. The effect of ionic strength on hydrogen generation was negligible, while the decrease of generated hydrogen in the acidic pH region (&gt;5.0) was observed. The mechanism of these mechanochemical reactions was discussed.

    DOI: 10.1246/bcsj.76.2153

    Web of Science

    researchmap

  • H-2 generation in wet grinding of granite and single-crystal powders and implications for H-2 concentration on active faults 査読

    J Kameda, K Saruwatari, H Tanaka

    GEOPHYSICAL RESEARCH LETTERS   30 ( 20 )   2003年10月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:AMER GEOPHYSICAL UNION  

    Granite and single crystals of quartz, alkali feldspar, biotite and muscovite are ground in pH-controlled and pure water solutions using a ball mill at ambient condition to examine the production of H-2. The amount of H-2 generated by grinding is linearly related with the surface area of ground samples. The slope of the straight line indicates H-2 productivity of each mineral: 3.9 x 10(-3) mumol/m(2) (quartz); 1.0 x 10(-3) mumol/m(2) (alkali feldspar); 3.6 x 10(-2) mumol/m(2) (biotite); 2.2 x 10(-2) mumol/m(2) (muscovite); 4.5 x 10(-3) mumol/m(2) (granite). High productivity of biotite and muscovite is probably related to the existence of hydroxyls in their crystal structures. Interestingly, H-2 production did not depend on the pH of the solution in the case of biotite and granite, while comparisons between fluid acidity and H-2 concentration on several active faults suggest that anomalously high H-2 is commonly observed at relatively acidic water springs. This correlation may be explained by locally high abundance of phyllosilicates.

    DOI: 10.1029/2003GL018252

    Web of Science

    researchmap

  • Growth of plastic shear zone and its duration inferred from theoretical consideration and observation of an ancient shear zone in the granitic crust 査読

    H Tanaka, B Shibazaki, N Shigematsu, K Fujimoto, T Ohtani, Y Miyashita, T Tomita, K Omura, Y Kobayashi, J Kameda

    EARTH PLANETS AND SPACE   54 ( 11 )   1207 - 1210   2002年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:TERRA SCIENTIFIC PUBL CO  

    A new model for growth of plastic shear zone is proposed based on the basis of a theory of fluid dynamics coupled with a rheological constitutive function, and is applied to a natural shear zone. Mylonite, ultramylonite and other ductile fault rocks are well known to deform in a plastic flow regime. The rheological behavior of these kinds of rocks has been well documented as a non-linear viscous body, which is empirically described as gamma = Atau'' exp(-Q/RT), where : strain rate, tau: shear stress, Q: activation energy, R: universal gas constant, tau: absolute temperature, and A and n are constants. Strain rate- and temperature-dependent viscosity is obtained by differentiating the equation, and simplified by substituting n = 1. Then, substitution of the equation into a diffusion equation, delta = 4rootvt, derives an equation delta = 4[t/p] . A exp(-Q/RT)(1/2), where delta: thickness of active layer of viscous deformation, v: kinematic viscosity, and p: density. The duration of creep deformation along the ancient plastic shear zone (thickness: 0.076 m) is estimated to be around 760 s, in a temperature range from 300 to 500degreesC. This estimation is rather good agreement with intermittent creep during inter-seismic period, than steady state creep or co-seismic slip.

    DOI: 10.1186/BF03353321

    Web of Science

    researchmap

  • サハリン最北部の地質構造からみた北米・ユーラシアプレート収束境界のテクトニクス

    亀田 純, 木村 学, Melinikov O.A, 早坂 康隆, 橋本 善孝, 坂島 隆彦, 新井 孝志, 芳野 極, 鈴木 紀毅

    地學雜誌   109 ( 2 )   235 - 248   2000年4月

     詳細を見る

    記述言語:日本語   出版者・発行元:公益社団法人 東京地学協会  

    The region from Sakhalin in Russia to the eastern margin of the Japan Sea has been regarded as a convergent plate boundary zone between the Eurasia and the North America Plates because large earthquakes and active crustal movements are prominent in this zone. These activities along the eastern margin of the Japan Sea to southern Sakhalin are almost consistent with the expected relative plate motion deduced from the Euler pole which is estimated from the magnetic anomaly lineations in the Atlantic Ocean, but the modern tectonic aspect in northern Sakhalin is inconsistent; &lt;I&gt;e.g.&lt;/I&gt;, 1995 Neftegorsk Earthquake is one of the typical events.&lt;BR&gt;As a result of a structural and tectonic study in northern Sakhalin, the NE-SW compressive tectonic feature since the Late Miocene was clarified. In the northernmost area of the Schmidt Peninsula, the early Cretaceous ophiolite thrusts upon the Late Cretaceous sedimentary rocks. The ophiolite has an overturned sequence: serpentinites, gabbros, basaltic rocks, and hemipelagic sediments in descending order. The Cretaceous sediments form a map-scale and NW vergent synclinorium. All the deformation structures in outcrop scale, such as micro-folds, minor reverse and normal faults, axial plane cleavages and bedding slips, are consistent with a large scale folding. These structural relationships suggest only one event of deformation, which appears to be linked to overthrusting of the ophiolitic rocks.&lt;BR&gt;A structural investigation of the southeastern part of the Schmidt Peninsula revealed that the Middle Miocene sediments composed of siltstone and sandstone are folded with wavelength of several tens to several hundred meters. Their fold axes trend in the NW direction, which indicates that deformation under the NE compression is the same as the deformation in the northernmost area. The thickness of sedimentary layers are constant everywhere in folding. This fact indicates that the timing of the deformation is after sedimentation, that is, after the Middle Miocene. This deformation event is consistent with modern activity in northern Sakhalin. Therefore, the modern tectonic framework might have started in the Late Miocene time.&lt;BR&gt;A plate tectonic model indicates that the modern relative motion between the Eurasia and the North America Plate started at about 11 m. y. ago. The Late Miocene onset of the modern tectonic framework in northern Sakhalin occurred at almost the same time. The most reliable model to explain the discrepancy of sense of movement from the Eurasia-North America retative motion, may be the &amp;ldquo;extrusion&amp;rdquo; of the Okhotsk Block toward the Pacific Ocean. The dextral extrusion boundary in northern Sakhalin may be traced along theeastern coast of Sakhalin to the northern edge of the Kuril Basin, where active seismicityhas been observed although a detailed study of focal mechanisms and other tectonic aspects is needed in the future.

    DOI: 10.5026/jgeography.109.2_235

    CiNii Article

    CiNii Books

    researchmap

▼全件表示

書籍等出版物

  • 揺れ動く大地 プレートと北海道

    木村 学, 宮坂省吾, 亀田 純( 範囲: 共著)

    北海道新聞社  2018年8月 

     詳細を見る

MISC

  • プレート沈み込み帯巨大分岐断層の古応力解析:延岡衝上断層の例

    川崎令詞, 浜橋真理, 橋本善孝, 大坪誠, 山口飛鳥, 北村有迅, 亀田純, 濱田洋平, 福地里菜, 木村学

    日本地質学会学術大会講演要旨   121st   2014年

     詳細を見る

  • 付加体内シュードタキライトの三次元造解析と断層すべり詳細の復元

    濱田洋平, 木村学, 亀田純, 山口飛鳥, 浜橋真理, 福地里菜, 北村有迅, 川崎令詞, 岡本伸也

    日本地質学会学術大会講演要旨   121st   2014年

     詳細を見る

  • シュードタキライトの3次元構造解析

    濱田洋平, 木村学, 亀田純, 山口飛鳥, 浜橋真理, 福地里菜, 北村有迅, 川崎令詞, 岡本伸也

    日本地質学会学術大会講演要旨   120th   2013年

     詳細を見る

  • 四万十付加体中の延岡衝上断層を貫くボーリングコアのイライトと緑泥石の変化

    福地里菜, 藤本光一郎, 亀田純, 木村学, 山口飛鳥, 浜橋真理, 北村有迅, 濱田洋平, 橋本善孝, 斎藤実篤

    日本地質学会学術大会講演要旨   120th   2013年

     詳細を見る

  • 四万十付加体中の延岡衝上断層を貫くボーリングコアを用いたイライト結晶化度の解析

    福地里菜, 藤本光一郎, 浜橋真理, 山口飛鳥, 木村学, 亀田純, 濱田洋平, 橋本善孝, 栄田美緒, 比名祥子, 北村有迅, 齊藤実篤, 水落幸広, 長谷和則, 明石孝行

    日本地質学会学術大会講演要旨   119th   2012年

     詳細を見る

  • 南海トラフへ沈み込む四国海盆玄武岩と火山砕屑岩類:IODP Expedition 322の成果

    斎藤 実篤, 久保 雄介, アンダーウッド マイク, IODP 第322次研究航海乗船研究者, 成瀬 元, 小田 啓邦, 中嶋 健, 佐藤 暢, 石塚 治, 山口 飛鳥, 亀田 純, 新正 裕尚

    日本地質学会学術大会講演要旨   2010   31 - 31   2010年

     詳細を見る

    記述言語:日本語   出版者・発行元:一般社団法人 日本地質学会  

    DOI: 10.14863/geosocabst.2010.0.31.0

    CiNii Article

    researchmap

  • FIB-TEMによる黄砂鉱物粒子の表面構造の観察

    関屋 麻理子, 亀田 純, 猿渡 和子, 小暮 敏博

    日本鉱物学会・学術講演会,日本岩石鉱物鉱床学会学術講演会講演要旨集   2007   189 - 189   2007年9月

     詳細を見る

  • P9 FIB-TEM法を用いたバーミキュラー状カオリンの構造およびポリタイプ解析

    亀田 純, 猿渡 和子, ダニエル ビューフォー, 小暮 敏博

    粘土科学討論会講演要旨集   ( 51 )   164 - 165   2007年9月

     詳細を見る

    記述言語:日本語   出版者・発行元:日本粘土学会  

    CiNii Article

    CiNii Books

    researchmap

  • 層状ニオブ酸ナノシートの永続的光伝導性

    佐藤久子, 岡本健太郎, 猿渡和子, 亀田純, 田村堅志, 小暮敏博, 山岸晧彦

    粘土科学討論会講演要旨集   51st   234 - 235   2007年9月

     詳細を見る

  • P-94 蛇紋岩を伴う反応帯中に産する緑泥石の結晶構造と変形組織との関係(13.岩石・鉱物の破壊と変形,ポスター発表,一般講演)

    亀田 純, 岡本 敦, 川端 訓代

    日本地質学会学術大会講演要旨   114   262 - 262   2007年9月

     詳細を見る

    記述言語:日本語   出版者・発行元:日本地質学会  

    CiNii Article

    CiNii Books

    researchmap

  • B25.LB法によって作成した粘土単一層膜修飾電極における電荷輸送過程の研究(一般講演 口頭発表,第50回粘土科学討論会発表論文抄録)

    吉田 純, 佐藤 久子, 猿渡 和子, 亀田 純, ビルモア ジル, 山岸 晧彦

    粘土科学   46 ( 1 )   82 - 82   2007年2月

     詳細を見る

    記述言語:日本語   出版者・発行元:日本粘土学会  

    CiNii Article

    CiNii Books

    researchmap

  • 断層内のメカノケミカル反応--水素ガスおよび水素イオン発生の素過程 (総特集 陸域震源断層--深部すべり過程のモデル化) -- (1章 物質科学的調査)

    田中 秀実, 亀田 純, 猿渡 和子

    号外地球   ( 50 )   45 - 49   2005年

     詳細を見る

    記述言語:日本語   出版者・発行元:海洋出版  

    CiNii Article

    CiNii Books

    researchmap

  • P52. 有機単分膜をテンプレートにしたブルーサイトの合成(第48回粘土科学討論会発表論文抄録)

    亀田 純, 猿渡 和子, 佐藤 久子, 山岸 晧彦

    粘土科学   44 ( 2 )   103 - 104   2004年12月

     詳細を見る

    記述言語:日本語   出版者・発行元:日本粘土学会  

    CiNii Article

    CiNii Books

    researchmap

▼全件表示

受賞

  • 研究総長賞(奨励賞)

    2017年1月   北海道大学  

    亀田純

     詳細を見る

共同研究・競争的資金等の研究

  • 粘着力に基づく新たな断層構成則の構築

    研究課題/領域番号:24K00721  2024年04月 - 2027年03月

    日本学術振興会  科学研究費助成事業  基盤研究(B)

    亀田 純, 濱田 洋平

      詳細を見る

    配分額:17810000円 ( 直接経費:13700000円 、 間接経費:4110000円 )

    researchmap

  • 断層の高速摩擦すべりに伴うトライボケミカル型水素発生プロセスの解明

    研究課題/領域番号:21H01185  2021年04月 - 2024年03月

    日本学術振興会  科学研究費助成事業  基盤研究(B)

    亀田 純, 鈴木 徳行, 廣瀬 丈洋

      詳細を見る

    配分額:17160000円 ( 直接経費:13200000円 、 間接経費:3960000円 )

    今年度は、断層内の岩石ー流体相互作用による反応生成物の探索を目的として、下記の3つの研究を行った。
    (1)沈み込み帯プレート境界域を構成する各種岩石試料を用いたラジカル反応実験:堆積岩、変成岩、火成岩試料を湿式粉砕し、溶液中の反応生成物を分析したところ、活性酸素種(過酸化水素)の生成が確認された。このことは地震活動によって断層内に酸化的流体が生成される可能性を示している。このような流体の挙動をさらに検討することにより、断層破壊の連鎖・進展プロセスの理解につながる可能性がある。
    (2)沈み込み帯プレート境界分岐断層近傍の残留ガス分析:九州四万十帯延岡断層を対象として、ガスクロマトグラフィーによる岩石残留ガス濃度組成分析(水素、二酸化炭素、メタン、エタンなど)を実施し、断層近傍における水素、二酸化炭素、メタンガスの顕著な濃度異常を確認した。これらは過去の地震活動によって生成・貯留されていると考えられ、当該断層における地震性すべり挙動の解明につながる重要な成果と考えられる。
    (3)地殻ーマントル境界断層近傍の残留ガス分析:オマーンオフィオライト下部のカンラン岩層およびそれと接する地殻岩石(メタモルフィックソール)を対象として、岩石残留ガス分析を行った。その結果、境界断層近傍において高濃度の水素・メタンが保持されていることが確認された。これらのガスは地殻岩石中にも見られたことから、オフィオライトが衝上した際のカンラン岩の蛇紋岩化作用に伴ってガスが生成し、それらが地殻岩石中へと拡散していったものと考えられる。この結果は、沈み込み帯深部における流体の生成・移行プロセスを理解する上で重要と考えられる。

    researchmap

  • 付加体深部ガスの続成・変成作用

    研究課題/領域番号:21K03712  2021年04月 - 2024年03月

    日本学術振興会  科学研究費助成事業  基盤研究(C)

    鈴木 徳行, 亀田 純

      詳細を見る

    配分額:2730000円 ( 直接経費:2100000円 、 間接経費:630000円 )

    (1)南海トラフの付加体・アンダースラスト堆積物の有機物濃度についての文献調査:フィリッピン海プレートの沈み込みに伴って地殻深部にもたらされる付加体とアンダースラスト堆積物の有機物(有機炭素)濃度について国際共同海洋研究プログラム(ODP/ DSDP/IODP)のInitial Report等を活用し調査研究を行った。
    (2)付加体とアンダースラスト堆積物中での熱分解起源メタン・水素生成の反応速度モデル:海洋プレートの沈み込みによってもたらされる堆積物の有機炭素濃度が低いことから,オイル・湿性ガスの排出が乏しいと考えられ,熱分解起源メタンの生成は閉鎖系で進行するものと見なせる。このような条件下での熱分解メタン生成の反応速度モデルを構築した。
    (3)付加体堆積岩中の残留ガス分析:改良した残留ガス分析システムによって古い付加体泥質岩中の残留ガス分析を行い,熱分解起源のメタンと水素の生成タイミングをあらためて確認した。
    (4)南海トラフ沈み込み帯での熱分解起源メタンのフラックス:南海トラフ熊野灘での付加体とアンダースラスト堆積物の移動速度について検討し,堆積有機物の昇温速度や熱分解起源メタンの生成速度を検討した。その結果,付加体よりもアンダースラスト堆積物中でのメタン生成速度がはるかに大きいことを明らかにした。
    (5)南海トラフ沈み込み帯における熱分解起源メタンの生成帯の広域的分布:同地域において沈み込んでいるアンダースラスト堆積物の熱分解起源メタン生成帯の地下分布を明らかにした。それと実際に観察される泥火山,ガスハイドレートまたはBSR(海底疑似反射面),水溶性ガス田の分布との関係について考察した。

    researchmap

  • 堆積物重力流の流動挙動評価

    研究課題/領域番号:18H01295  2018年04月 - 2021年03月

    日本学術振興会  科学研究費助成事業  基盤研究(B)

    亀田 純

      詳細を見る

    配分額:17810000円 ( 直接経費:13700000円 、 間接経費:4110000円 )

    2018年9月6日に北海道胆振東部地震(Mw6.7)が発生した。地震による強い揺れは、震源付近の丘陵地一帯に大規模な斜面崩壊をもたらした。本研究では、地すべり面の粒子表面物性に注目して斜面崩壊の発生メカニズムを検討した。調査の結果、斜面に堆積する火山灰層(樽前d)最下部のすべり面からハロイサイト粘土鉱物が確認された。これらのハロイサイトは球形~不定形を呈し高い保水性を示すこと、また粒子表面は広いpH領域において負に帯電していることが分かった。降雨時には粒子間反発力が高まることで土壌粘着力が低下することが示唆され、このような性質が斜面の不安定化や土砂の高い流動性をもたらしたと考えられる。

    researchmap

  • 断層内の非晶質珪酸塩の構造と成因

    研究課題/領域番号:15H03746  2015年04月 - 2018年03月

    日本学術振興会  科学研究費助成事業  基盤研究(B)

    亀田 純, 杉山 和正, 堤 昭人, 竹下 徹

      詳細を見る

    配分額:14430000円 ( 直接経費:11100000円 、 間接経費:3330000円 )

    断層内の含水粘土鉱物の熱的・機械的非晶質化過程について検討した。カオリナイトと緑泥石の高温脱水実験により、これらの鉱物が異なる温度で脱水非晶質化すること、またその反応進行度をX線回折法により評価可能であることが分かった。この性質は、沈み込み帯地震断層の新たな温度評価指標として有用である。また、機械的作用による脱水反応の促進効果が認められたが、これは鉱物層間の水素結合の選択的破壊に起因していることが分かった。南海トラフの地震断層では、断層面において選択的に相転移反応が進行しており、これは断層すべりに伴って反応の活性化エネルギーが低下することでもたらされることを明らかにした。

    researchmap

  • 観察・観測による断層帯の発達過程とミクロからマクロまでの地殻構造の解明

    研究課題/領域番号:26109004  2014年07月 - 2019年03月

    日本学術振興会  科学研究費助成事業  新学術領域研究(研究領域提案型)

    竹下 徹, 酒井 慎一, 豊島 剛志, 藤内 智士, 奥平 敬元, 加藤 愛太郎, 小林 健太, 松本 聡, 亀田 純, 廣野 哲朗, 藤本 光一郎, 重松 紀生, 向吉 秀樹

      詳細を見る

    配分額:224510000円 ( 直接経費:172700000円 、 間接経費:51810000円 )

    本研究では、2000年鳥取県西部地震の震源地域における世界に例を見ない小さなスケール(sub-km)の分解能での地震観測により複雑な断層面の形状や非ダブルカップル地震の存在が初めて明らかにされた。また、現在の余震は中新世以来形成された地質断層の再活動によることが明らかとなった。成熟した白亜紀後期に形成された中央構造線断層帯について、断層帯のアーキテクチャーが高精度で明らかになったほか、歪の局所化の過程と原因の究明に進展があった。また、本来流動的な下部地殻の断層帯においても地震性の破壊は生じており、破壊した細粒岩石では反応促進の粒径依存型のクリープで変形が進行していることが明らかとなった。

    researchmap

  • 中―高速域における断層の摩擦化学反応過程と断層強度弱化の機構解明

    研究課題/領域番号:24340104  2012年04月 - 2015年03月

    日本学術振興会  科学研究費助成事業  基盤研究(B)

    堤 昭人, 下林 典正, 三宅 亮, 亀田 純, 並木 由香

      詳細を見る

    配分額:17290000円 ( 直接経費:13300000円 、 間接経費:3990000円 )

    摩擦化学反応に起因する,珪質岩石の強度弱化の機構を明らかすることを目的として,丹波帯のチャートを用いた摩擦実験後の断層表面のナノスケール観察を行った.また,中米海溝コスタリカ沖に沈み込む珪質堆積物を用いた摩擦実験をおこなった.その結果,高速弱化を示すチャート中の断層表面が,数百ミクロン程度の水和化非晶質シリカの薄層で覆われていることが明らかになった.また,非晶質シリカを主体とする断層物質を含む断層の低速での摩擦速度依存性が負であることが分かった.これらの結果は,水和化非晶質シリカの存在が,断層の速度依存性と高速での強度低下の機構に重要な影響を及ぼしていることを意味している

    researchmap

  • 海溝型地震発生機構の理解:シリカ・粘土続成作用からのアプローチ

    研究課題/領域番号:24740339  2012年04月 - 2015年03月

    日本学術振興会  科学研究費助成事業  若手研究(B)

    亀田 純

      詳細を見る

    配分額:4420000円 ( 直接経費:3400000円 、 間接経費:1020000円 )

    東北沖地震では、従来地震が起こらないと考えられていた海溝先端まで断層すべりが伝播し、巨大津波を引き起こしたと考えられている。このような海溝浅部における断層運動の実態解明を目指して、プレート境界断層を含む掘削試料の鉱物分析を行った。分析の結果、プレート境界断層において高い濃度でスメクタイトが濃集していることが確認された。スメクタイトは、摩擦強度が小さく、高速すべり時には効果的に断層強度を低下させることが知られている。したがって、日本海溝におけるプレート境界断層の浅部断層すべりは、スメクタイトに富むという断層の鉱物学的特徴に強く影響を受けているものと考えられる。

    researchmap

  • メカノケミストリーを応用した断層内鉱物相転移反応に関する研究

    研究課題/領域番号:22840018  2010年 - 2011年

    日本学術振興会  科学研究費助成事業  研究活動スタート支援

    亀田 純

      詳細を見る

    配分額:3120000円 ( 直接経費:2400000円 、 間接経費:720000円 )

    浅部化石付加体である三浦-房総付加体に発達する沈み込み帯前縁断層(白子断層、浅間断層)を対象として粘土鉱物分析を行った。その結果、いずれの断層においても断層内部(断層ガウジ)における局所的なスメクタイト-イライト相転移反応の進行が見られた。この反応はおそらく断層運動時の摩擦発熱によるものと考えられ、地震性の高速すべりが付加体先端部まで到達していたことの物的証拠と考えられる。

    researchmap

▼全件表示

 

担当授業科目

  • 地球惑星物質科学概論 (2024年度) 前期  - 月3~4

  • 地球惑星表層変動学 (2024年度) 前期  - その他

  • 地球惑星表層変動学特論 (2024年度) 後期  - その他

  • 実験地球惑星物理学特別演習 (2024年度) 通年  - その他

  • 惑星表層環境学演習 (2024年度) 後期  - その他

  • 特別研究 (2024年度) その他  - その他

▼全件表示