Geometry of the Nojima Fault at Nojima-Hirabayashi, Japan – II. Microstructures and their Implications for Permeability and Strength     

Diane E. Moore  David A. Lockner  Hisao Ito  Riuji Ikeda  Hidemi Tanaka  Kentaro Omura 《Pure and Applied Geophysics》2009,166(10-11):1669-1691

Samples of damage-zone granodiorite and fault core from two drillholes into the active, strike-slip Nojima fault zone display microstructures and alteration features that explain their measured present-day strengths and permeabilities and provide insight on the evolution of these properties in the fault zone. The least deformed damage-zone rocks contain two sets of nearly perpendicular (60–90° angles), roughly vertical fractures that are concentrated in quartz-rich areas, with one set typically dominating over the other. With increasing intensity of deformation, which corresponds generally to increasing proximity to the core, zones of heavily fragmented rock, termed microbreccia zones, develop between prominent fractures of both sets. Granodiorite adjoining intersecting microbreccia zones in the active fault strands has been repeatedly fractured and locally brecciated, accompanied by the generation of millimeter-scale voids that are partly filled with secondary minerals. Minor shear bands overprint some of the heavily deformed areas, and small-scale shear zones form from the pairing of closely spaced shear bands. Strength and permeability measurements were made on core collected from the fault within a year after a major (Kobe) earthquake. Measured strengths of the samples decrease regularly with increasing fracturing and fragmentation, such that the gouge of the fault core and completely brecciated samples from the damage zone are the weakest. Permeability increases with increasing disruption, generally reaching a peak in heavily fractured but still more or less cohesive rock at the scale of the laboratory samples. Complete loss of cohesion, as in the gouge or the interiors of large microbreccia zones, is accompanied by a reduction of permeability by 1-2 orders of magnitude below the peak values. The core samples show abundant evidence of hydrothermal alteration and mineral precipitation. Permeability is thus expected to decrease and strength to increase somewhat in active fault strands between earthquakes, as mineral deposits progressively seal fractures and fill pore spaces.  相似文献   

SHRIMP zircon and EPMA monazite dating of granitic rocks from the Maizuru terrane, southwest Japan: Correlation with East Asian Paleozoic terranes and geological implications   总被引：1，自引：0，他引：1  

Masahiro  Fujii  Yasutaka  Hayasaka  Kentaro  Terada 《Island Arc》2008,17(3):322-341

Abstract The Maizuru terrane, distributed in the Inner Zone of southwest Japan, is divided into three subzones (Northern, Central and Southern), each with distinct lithological associations. In clear contrast with the Southern zone consisting of the Yakuno ophiolite, the Northern zone is subdivided into the western and eastern bodies by a high-angle fault, recognized mainly by the presence of deformed granitic rocks and pelitic gneiss. This association suggests an affinity with a mature continental block; this is supported by the mode of occurrence, and petrological and isotopic data. Newly obtained sensitive high mass-resolution ion microprobe (SHRIMP) zircon U–Pb ages reveal the intrusion ages of 424 ± 16 and 405 ± 18 Ma (Siluro–Devonian) for the granites from the western body, and 249 ± 10 and 243 ± 19 Ma (Permo–Triassic) for the granodiorites from the eastern body. The granites in the western body also show inherited zircon ages of around 580 and 765 Ma. In addition, electron probe microanalysis (EPMA) monazite U–Th–total Pb dating gives around 475–460 Ma. The age of intrusion, inherited ages, mode of occurrence, and geological setting of the Siluro–Devonian granites of the Northern zone all show similarities with those of the Khanka Massif, southern Primoye, Russia, and the Hikami granitic rocks of the South Kitakami terrane, Northeast Japan. We propose that both the Siluro–Devonian and Permo–Triassic granitic rocks of the Northern zone are likely to have been juxtaposed through the Triassic–Late Jurassic dextral strike-slip movement, and to have originated from the Khanka Massif and the Hida terrane, respectively. This study strongly supports the importance of the strike-slip movement as a mechanism causing the structural rearrangement of the Paleozoic–Mesozoic terranes in the Japanese Islands, as well as in East Asia.  相似文献   

Review on observational studies of western tropical Pacific Ocean circulation and climate     

Hu  Dunxin  Wang  Fan  Sprintall  Janet  Wu  Lixin  Riser  Stephen  Cravatte  Sophie  Gordon  Arnold  Zhang  Linlin  Chen  Dake  Zhou  Hui  Ando  Kentaro  Wang  Jianing  Lee  Jae-Hak  Hu  Shijian  Wang  Jing  Zhang  Dongxiao  Feng  Junqiao  Liu  Lingling  Villanoy  Cesar  Kaluwin  Chalapan  Qu  Tangdong  Ma  Yixin 《中国海洋湖沼学报》2020,38(4):906-929

The Western Tropical Pacific(WTP) Ocean holds the largest area of warm water(28℃) in the world ocean referred to as the Western Pacific Warm Pool(WPWP),which modulates the regional and global climate through strong atmospheric convection and its variability.The WTP is unique in terms of its complex 3-D ocean circulation system and intensive multiscale variability,making it crucial in the water and energy cycle of the global ocean.Great advances have been made in understanding the complexity of the WTP ocean circulation and associated climate impact by the international scientific community since the 1960 s through field experiments.In this study,we review the evolving insight to the 3-D structure and multi-scale variability of the ocean circulation in the WTP and their climatic impacts based on in-situ ocean observations in the past decades,with emphasis on the achievements since 2000.The challenges and open que stions remaining are reviewed as well as future plan for international study of the WTP ocean circulation and climate.  相似文献   

Sound velocity and elastic properties of Fe–Ni and Fe–Ni–C liquids at high pressure     

Soma Kuwabara  Hidenori Terasaki  Keisuke Nishida  Yuta Shimoyama  Yusaku Takubo  Yuji Higo  Yuki Shibazaki  Satoru Urakawa  Kentaro Uesugi  Akihisa Takeuchi  Tadashi Kondo 《Physics and Chemistry of Minerals》2016,43(3):229-236

The sound velocity (V _P) of liquid Fe–10 wt% Ni and Fe–10 wt% Ni–4 wt% C up to 6.6 GPa was studied using the ultrasonic pulse-echo method combined with synchrotron X-ray techniques. The obtained V _P of liquid Fe–Ni is insensitive to temperature, whereas that of liquid Fe–Ni–C tends to decrease with increasing temperature. The V _P values of both liquid Fe–Ni and Fe–Ni–C increase with pressure. Alloying with 10 wt% of Ni slightly reduces the V _P of liquid Fe, whereas alloying with C is likely to increase the V _P. However, a difference in V _P between liquid Fe–Ni and Fe–Ni–C becomes to be smaller at higher temperature. By fitting the measured V _P data with the Murnaghan equation of state, the adiabatic bulk modulus (K _S0) and its pressure derivative (K _S ^′ ) were obtained to be K _S0 = 103 GPa and K _S ^′  = 5.7 for liquid Fe–Ni and K _S0 = 110 GPa and K _S ^′  = 7.6 for liquid Fe–Ni–C. The calculated density of liquid Fe–Ni–C using the obtained elastic parameters was consistent with the density values measured directly using the X-ray computed tomography technique. In the relation between the density (ρ) and sound velocity (V _P) at 5 GPa (the lunar core condition), it was found that the effect of alloying Fe with Ni was that ρ increased mildly and V _P decreased, whereas the effect of C dissolution was to decrease ρ but increase V _P. In contrast, alloying with S significantly reduces both ρ and V _P. Therefore, the effects of light elements (C and S) and Ni on the ρ and V _P of liquid Fe are quite different under the lunar core conditions, providing a clue to constrain the light element in the lunar core by comparing with lunar seismic data.  相似文献   

Computer simulation of fracturing of layered rock     

I. Hattori  S. Mizutani 《Engineering Geology》1971,5(4):253-269

Fracturing of rocks is simulated using an electronic computer, on the assumption that when a stress acts on a model, the fracturing condition is determined according to Mohr's theory and that of Griffith. A rock body is regarded as an aggregate of a grid cell whose strength is expressed by a random number of Gaussian distribution functions and the layered fabric of the rock body is given by inserting layered parts with different strength and with various inclinations. The results displaying the fractures on the grid system suggest that some of the geologic structures such as the echelon or the zigzag pattern of fracture are ascribed to fracturing in a layered or heterogeneous body, and variation of strength and the presence of layered fabric in a rock have a significant influence on fracture patterns developed in the rock.  相似文献   

The extinction coefficients in mid- and farinfrared of silicate and iron-oxide minerals of interest for astronomical observations     

Chiyoe Koike  Hiroichi Hasegawa  Noriaki Asada  Takeshi Hattori 《Astrophysics and Space Science》1981,79(1):77-85

Extinction measurements were made for some silicate and iron-oxide mineral grains in mid- and far-infrared region. For far-infrared region, high temperature magnesium silicates such as olivine and pyroxenes show the absorption spectra of steep dependence as ^–3 ( being the wavelength) with some peak structure, but the spectrum of magnetite shows ^–1 dependence.  相似文献   

CFC Indicating Renewal of the Japan Sea Deep Water in Winter 2000–2001     

Shizuo Tsunogai  Kentaro Kawada  Shuichi Watanabe  Takafumi Aramaki 《Journal of Oceanography》2003,59(5):685-693

The distributions of CFC (chlorofluorocarbon) in the water column was determined twice in 2000 and 2001 in the northwestern Japan Sea. In 2000 the CFC-11 concentration decreased almost exponentially with depth from 6 pmol/kg at a few hundred m deep to 0.3 pmol/kg or less at the bottom of about 3400 m depth at three stations (40–41°N, 132–133°E) about 300 km off Vladivostok. In 2001 the CFC-11 concentration increased sharply up to 2 pmol/kg in the bottom water, while it did not increase at a station (42.0°N, 136.5°E) about 450 km away to the northeast. This is due to the renewal of the bottom water which is replaced by the surface water flowing down along the continental slope, as suggested by Tsunogai et al. (1999), who proposed the continental shelf pump. Furthermore, an increase in the CFC-11 concentration was observed throughout the entire water column above 3000 m depth, although the proportion of the increase was about 20%, which was one order of magnitude smaller than that in the bottom water. The increase in inventory is almost four times larger than that in the bottom water below 3000 m depth which is equivalent to about 1/6 of the total inventory found in 2000. The increase also means that 3% of the deep water was replaced by the recent surface water, or, if the turnover occurs every year, that the turnover time of the deep water to be about 30 years. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

Variation of carbon and nitrogen uptake capacity in a regional upwelling area around Hachijo Island     

Jota Kanda  Toshiro Saino  Akihiko Hattori 《Journal of Oceanography》1985,41(6):373-380

Capacities for inorganic carbon, nitrate and ammonium uptake were measured around Hachijo Island, 300 km south of Tokyo, where local upwelling occurred. The phytoplankton population inside the upwelling area had a high capacity for nitrate uptake and a low capacity for uptake of ammonium. Nutrient concentration and phytoplankton biomass were higher in the upwelling plume than outside. On a chlorophylla basis, phytoplankton populations inside the upwelling area showed a lower capacity for carbon and nitrogen uptake than those outside the upwelling. Low temperature, relatively limited availability of light caused by extensive water mixing within the upwelling plume, and the difference in species composition of phytoplankton must be considered in explaining these lower uptake capacities.  相似文献   

Spatial Variability of Living Coccolithophore Distribution in the Western Subarctic Pacific and Western Bering Sea   总被引：1，自引：0，他引：1  

Hiroshi Hattori  Makoto Koike  Kenichi Tachikawa  Hiroaki Saito  Kazuya Nagasawa 《Journal of Oceanography》2004,60(2):505-515

Vertical distributions of coccolithophores were observed in the depth range 0–50 m in the western subarctic Pacific and western Bering Sea in summer, 1997. Thirty-five species of coccolithophores were collected. Overall, Emiliania huxleyi var. huxleyi was the most abundant taxon, accounting for 82.8% of all coccolithophores, although it was less abundant in the western Bering Sea. Maximum abundance of this species was found in an area south of 41°N and east of 175°E (Transition Zone) reaching >10,000 cells L⁻¹ in the water column. In addition to this species, Coccolithus pelagicus f. pelagicus, which accounted for 4.2% of the assemblage, was representative of the coccolithophore standing crop in the western part of the subarctic Pacific. Coccolithus pelagicus f. hyalinus was relatively abundant in the Bering Sea, accounting for 2.6% of the assemblage. Coccolithophore standing crops in the top 50 m were high south of 41°N (>241 × 10⁶ cells m⁻²) and east of 170°E (542 × 10⁶ cells m⁻²) where temperatures were higher than 12°C and salinities were greater than 34.2. The lowest standing crop was observed in the Bering Sea and Oyashio areas where temperatures were lower than 6–10°C and salinities were less than 33.0. From the coccolithophore volumes, the calcite stocks in the Transition, Subarctic, and the Bering Sea regions were estimated to be 73.0, 9.7, and 6.9 mg m⁻², respectively, corresponding to calcite fluxes of 3.6, 0.5, and 0.3 mg m⁻²d⁻¹ using Stoke's Law. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

Serpentinites act as sponges for fluid‐mobile elements in abyssal and subduction zone environments     

Fabien Deschamps  Stéphane Guillot  Marguerite Godard  Muriel Andreani  Kéiko Hattori 《地学学报》2011,23(3):171-178

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