Petrology of ultramafic nodules from West Kettle River,near Kelowna,Southern British Columbia     

Toshitsugu Fujii  Christopher M. Scarfe 《Contributions to Mineralogy and Petrology》1982,80(4):297-306

A basanitoid flow of Miocene age, exposed near the West Kettle River, 25 km southeast of Kelowna, British Columbia, contains abundant ultramafic and mafic nodules. The subangular nodules are 1–20 cm across and typically show granular textures. A study of 250 nodules indicates that spinel lherzolite (60%) is the dominant type with subordinate olivine websterite (10%), websterite (7%), clinopyroxenite (4%), wehrlite (4%), pyroxene gabbro (4%), dunite (2%), harzburgite (1%) and granitic rocks (8%). Ultramafic nodules are of two types. Most of the wehrlites and clinopyroxenites belong to the black pyroxene (aluminous clinopyroxene) series, whereas the other clinopyroxene-bearing nodules belong to the green pyroxene (chromian diopside) series. Some spinel lherzolite nodules have distinctive pyroxene- and olivine-rich bands. Microprobe analyses of the constituent minerals of more than thirty nodules from the green pyroxene series indicate that grain to grain variations within individual nodules are small even when banding is present. Olivine, orthopyroxene, clinopyroxene and spinel in spinel lherzolite have average compositions of Fo₉₀, En₉₀, Wo₄₇Fs₅En₄₈, Cr/(Cr+ Al+Fe³)=0.1 and Mg/(Mg+Fe²⁺)=0.8. Equilibration temperatures, which were calculated using the two pyroxene geothermometer of Wells (1977), range between 920–980° C. Based on published phase stability experiments, pressures of equilibration are between 10–18 kbar. In summary, the upper mantle beneath southern British Columbia is dominated by spinel lherzolite but contains some banding on a scale of cm to meters. The temperature in the upper mantle is 950° C at a depth of 30–60 km.On leave from the Geological Institute, University of Tokyo, Japan  相似文献   

Anomalous crustal strain prior to the 1923 Kanto,Japan, earthquake as deduced from analysis of old triangulation data     

Yoichiro Fujii  Katsumi Nakane 《Pure and Applied Geophysics》1979,117(6):1301-1315

Horizontal earth's strains preceding the Kanto, Japan, earthquake of 1, September 1923, are deduced from the analysis of the old triangulation data. The anomalous strains that are several times larger than usual tectonic strain are found in the western part of Tokyo Bay, Sagamihara district, Japan for the observational period 1882/91–1898/1910, while any significant strain is not revealed in the other region of the Kanto district. The Kanto district was surveyed twice during the period 1883/85–1890/92 in the west and during the period 1890/92–1897/99 in the east respectively. The polarity of the detected anomalous strains, the directions and the signs of the principal strains, are quite the same as those of the postseismic crustal strains during the period 1924–74, and are reversed as compared to the coseismic one.The Philippine Sea plate thrusts under the South Kanto district with N25°W direction and pulls down the land during the interseismic period. The aseismic reverse faulting would begin several decades before the 1923 Kanto earthquake along the deep interface between the Asian plate and the convergent Philippine Sea plate. The down-going along the locked part of the interface would be accelerated, thus the compressional stress on the earth's surface might be concentrated over the deep fault plane together with the acceleration of the subsidence at the tip of the peninsula close to the Sagami trough.  相似文献   

Thermophysical properties of lunar material returned by Apollo missions     

Ki-Iti Horai  Naoyuki Fujii 《Earth, Moon, and Planets》1972,4(3-4):447-475

Data on thermophysical properties measured on lunar material returned by Apollo missions are reviewed. In particular, the effects of temperature and interstitial gaseous pressure on thermal conductivity and diffusivity have been studied. For crystalline rocks, breccias and fines, the thermal conductivity and diffusivity decrease as the interstitial gaseous pressure decreases from 1 atm to 10^–4T. Below 10^–4T, these properties become insensitive to the pressure. At a pressure of 10^–4T or below, the thermal conductivity of fines is more temperature dependent than that of crystalline rocks and breccias. The bulk density also affects the thermal conductivity of the fines. An empirical relationship between thermal conductivity, bulk density and temperature derived from the study of terrestrial material is shown to be consistent with the data on lunar samples. Measurement of specific heat shows that, regardless of the differences in mineral composition, crystalline rocks and fines have almost identical specific heat in the temperature range between 100 and 340K. The thermal parameter calculated from thermal conductivity, density and specific heat shows that the thermal properties estimated by earth-based observations are those characteristic only of lunar fines and not of crystalline rocks and breccias. The rate of radioactive heat generation calculated from the content of K, Th and U in lunar samples indicates that the surface layer of the lunar highland is more heat-producing than the lunar maria. This may suggest fundamental differences between the two regions.Now at Lamont-Doherty Geological Observatory, Columbia University, Palisades, New York, U.S.A.  相似文献   

Detailed horizontal crustal movements associated with the 1923 Kanto earthquake as deduced from network adjustment of old data including the third order triangulation stations     

Yoichiro Fujii   《Journal of Geodynamics》2003,35(4-5):457-469

The crustal movements associated with the 1923 Kanto, Japan, earthquake of magnitude 7.9 are deduced from the results of network adjustments with the pre-seimic and post-seismic geodetic data including up to the third order triangulation. The average spacing of the third triangulation is 4 km of higher density as compared with the first order triangulation and the second order triangulation, so we can expect to find much more detailed behavior of the released crustal strain. The main rupture of the 1923 Kanto earthquake that had occurred in the Sagami Bay has been estimated from the crustal deformations deduced from repetition of the first order triangulation and the second order triangulation, while the detailed deformations associated with the secondary faulting are deduced for the first case from the repeated third order triangulation. We find evidence for the secondary faultings in the south Kanto district, Japan, mainly from the pattern of the released strain with the order of 10⁻⁴ and some of them are associated with the surface breakages. We carefully investigate whether these secondary faultings had originated with fracturing at the depth or not. We cannot find any evidence for deep fracturing, though we find remarkable high earth strain release along some secondary faultings. This is mainly due to the fact that the area of high released strain is very limited and narrow along the direction perpendicular to the faulting.  相似文献   

Response to the comment by R. Stalder on “composition of aqueous fluid coexisting with mantle minerals at high pressure and its bearing on the differentiation of the earth’s mantle”     

Kenji Mibe  Toshitsugu Fujii 《Geochimica et cosmochimica acta》2004,68(4):929-930

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Source mechanism of a large scale gas outburst at Sunagawa Coal Mine in Japan     

K. Sato  Y. Fujii 《Pure and Applied Geophysics》1989,129(3-4):325-343

On January 29ty, 1986, the third largest gas outburst in Japan took place at Sunagawa Coal Mine, which is the only hydraulic mine in Japan. It occurred at a face of a cross-cut, just after a coal seam was outcropped by blasting for drivage of the cross-cut. The site of the gas outburst was located 1,180 m below the surface. No workers were injured, but the cross-cut was plugged with 1,600 m³ of coal fragments extending over 100 m behind the face and 60,000 m³ of methane gas was emitted.The site of the gas outburst was investigated in detail to clarify the geological features. A normal and a reverse fault existed at the site. The area of the ejected zone was about 400 m² and extended upward along the normal fault. The shape of the ejected zone suggests a great role of the normal fault on the gas outburst.Digital seismograms, recorded by a mine-wide seismic array at the coal mine, consisting of 27 microseismic events were used to investigate the gas outburst. Magnitude, seismic energy release, distribution of hypocenter and focal mechanism were analyzed. Taking the shape of the ejected zone together with results of the seismological investigation into consideration, it appears that the seismicity started with left-lateral faulting of the reverse fault and then right-lateral faulting of the normal fault followed. The faulting of the normal fault might be the direct cause and be the predominant mechanism of the gas outburst.Presented at the Fred Leighton Memorial Workshop on Mining Induced Seismicity, Montreal, Canada, August 30, 1987.  相似文献   

Thinning of the near-earth (10∼15 R_E) plasma sheet preceding the substorm expansion phase     

A. Nishida  K. Fujii 《Planetary and Space Science》1976,24(9):849-853

The timing of the plasma-sheet thinning relative to the onset of the expansion phase of substorms is examined by the analysis of the OGO 5 electron (79 ± 23 keV) and proton (100～150 keV) data with the aid of simultaneous magnetic field observations. It is found that the timing of the thinning is significantly dependent on the distance. At $\text{x}{}^2\text{+ y}{}^2\text{? 15 R}{}_{\mathrm{E}}$ the thinning often starts before the onset, while at $\text{x}{}^2\text{+ y}{}^2\text{? 15 R}{}_{\mathrm{E}}$ it tends to occur after the onset, where x and y refer to solar magnetospheric coordinates. The thinning that precedes the expansion-phase onset has been found to reduce the thickness to ～1 R_E, and further thinning may occur in a spatially limited region. Hence it is conceivable that the formation of the neutral line characterizing the substorm expansion phase is the consequence of the thinning of the plasma sheet in the near-Earth region.  相似文献   

Simultaneous seeing measurement through the Subaru Telescope in the visible and near-infrared bands for the wavelength dependence evaluation     

Shin Oya  Hiroshi Terada  Yutaka Hayano  Makoto Watanabe  Masayuki Hattori  Yosuke Minowa 《Experimental Astronomy》2016,42(1):85-98

Stellar images have been obtained under natural seeing at visible and near-infrared wavelengths simultaneously through the Subaru Telescope at Mauna Kea. The image quality is evaluated by the full-width at the half-maximum (FWHM) of the stellar images. The observed ratio of FWHM in the V-band to the K-band is 1.54 ± 0.17 on average. The ratio shows tendency to decrease toward bad seeing as expected from the outer scale influence, though the number of the samples is still limited. The ratio is important for simulations to evaluate the performance of a ground-layer adaptive optics system at near-infrared wavelengths based on optical seeing statistics. The observed optical seeing is also compared with outside seeing to estimate the dome seeing of the Subaru Telescope.  相似文献   

Development of a flood water level estimation method using satellite images and a digital elevation model for the Mekong floodplain     

Kenji Tanaka  Yoichi Fujihara  Keisuke Hoshikawa  Hideto Fujii 《水文科学杂志》2019,64(2):241-253

We have developed a flood water level estimation method that only employs satellite images and a DEM. The method involves three steps: (1) discriminating flood areas and identifying clumps of each flood area, (2) extracting the edges of the identified flood area using a buffering technique, and (3) performing spatial interpolation to transform the extracted elevation to flood water levels. We compared the estimated flood water levels with the observed ones. The RMSE using the RADARSAT was 1.99 and 1.30 m at river and floodplain points, respectively, whereas the RMSE using the MODIS was 4.33 and 1.33 m at the river and floodplain points, respectively. Given that most errors are attributed to the DEM, the method exhibited good performance. Furthermore, the method reproduced the flow directions and flood water level changes during the flooding period. Thus, we demonstrated that the characteristics of flood inundation can be understood even when ground observation data cannot be obtained.  相似文献   

Roles of Physical Processes in the Carbon Cycle Using a Simplified Physical Model     

Masahiko Fujii  Motoyoshi Ikeda  Yasuhiro Yamanaka 《Journal of Oceanography》2000,56(6):655-666

A simplified physical model is proposed in this article to describe differences among basins in substance distributions which were not well described by previous simplified models. In the proposed model, the global ocean is divided into the Pacific/Indian Ocean (PI), the Atlantic Ocean (AT), the Southern Ocean and the Greenland/Iceland/Norwegian Sea. The model is consisted of five physical parameters, namely the air-sea gas exchange, the thermohaline circulation, the horizontal and vertical diffusions, and the deep convection in the high-latitude regions. Individual values of these parameters are chosen by optimizing model distribution of natural ¹⁴C as a physical tracer. The optimal value for a coefficient of vertical diffusion in the low-latitude region is 7.5 × 10^–5 [m²s^–1]. Vertical transports by the Antarctic Bottom Water and the North Atlantic Deep Water are estimated at 1.0 Sv and 9.0 Sv. Global-mean air-sea gas exchange time is calculated at 9.0 years. Using these optimal values, vertical profiles of dissolved inorganic carbon without biological production in PI and AT are estimated. Oceanic responses to anthropogenic fluctuations in substance concentrations in the atmosphere induced by the industrialization and nuclear bomb are also discribed, i.e., the effects appear significantly in AT while a signal is extremely weak in PI. A time-delay term is effective to make the PI water older near the bottom boundary.  相似文献