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121.
Ian A. Navarrete Kiyoshi Tsutsuki Victor B. Asio Renzo Kondo 《Environmental Geology》2009,58(6):1257-1268
This study was conducted to evaluate the physical, chemical, and mineralogical characteristics of rain forest soils derived
from late Quaternary basaltic rocks in Leyte, Philippines. Four sites along a catena were selected at an elevation of 75–112 m
above sea level with an average annual rainfall of 3,000 mm and an average temperature of 28°C. Results indicate that the
soils are deep, clayey, and reddish in color, which is indicative of the advanced stage of soil development. They also posses
excellent physical condition (friable and highly porous) although they are plastic and sticky when wet as is usual for clayey
soils. In terms of chemical characteristics, the soils are acidic with low CEC values and generally low in organic matter
and nutrient contents. The clay mineralogy of the soils is dominated by halloysite and kaolinite with minor amounts of goethite
and hematite, and they also have generally high dithionite-extractable Fe contents confirming the advanced stage of their
development. The soils in the more stable slope positions (PL-1, PL-2, and PL-4) have generally similar characteristics and
appeared more developed than the one in the less stable position (PL-3). The most important pedogenic processes that formed
the soils appear to be weathering, loss of bases and acidification, desilification, ferrugination, clay formation and translocation,
and structure formation. The nature of the parent rock and climatic conditions prevailing in the area as well as slope position
appear to have dominant effects on the development of the soils. 相似文献
122.
Real-time monitoring of wind and surface waves in Otsuchi Bay, Iwate, Tohoku, Japan, commenced in October 2012, using a mooring buoy with an ultrasonic anemometer and a single-mode GPS wave sensor. Wind and wave data are distributed hourly in real time via the Internet along with a chart of their time series. We analyzed data monitored in the first 3 months in order to assess the variability and occurrence of wind and waves and to elucidate the main reasons for wave variation in Otsuchi Bay. The monitoring data revealed that surface waves in the bay were predominantly affected by swells propagated from the northeastern offshore region and that the wave height was significantly correlated with the component of wind velocity toward Otsuchi Bay in the northeastern offshore region that faces the bay mouth. The offshore wind field was expected to provide information useful for predicting coastal waves in a ria bay in Sanriku such as Otsuchi Bay. However, it should be emphasized that the horizontal distribution of the offshore wind field which has a significant effect on the surface waves in a ria bay depends heavily on the topographic shape of the bay. 相似文献
123.
Hitoshi Mikada Kyohiko Mitsuzawa Hiroyuki Matsumoto Tomoki Watanabe Shigehiko Morita Riyo Otsuka Hiroko Sugioka Toshitaka Baba Eiichiro Araki Kiyoshi Suyehiro 《Tectonophysics》2006,426(1-2):95
At the 2003 Tokachi-oki earthquake of M8, seafloor phenomena such as a generation process of tsunami, seafloor uplifts, turbidity current, etc., were observed using a cabled observatory installed on the seafloor. The turbidity current was observed as a benthic storm caused presumably by the mainshock. The seafloor uplifts were observed at the mainshock and continuously after the mainshock. The uplifts were 0.35, 0.37, and 0.12 m for epicentral distances of 25.5, 31.4, and 81.7 km, respectively. After the mainshock, a continuous uplift of the seafloor is observed at all three pressure gauge locations indicating that there was a change in the state of friction on the plate boundary interface by the mainshock. In this paper, we first show what was observed using the cabled observatory installed right above the focal area of the earthquake, and then we discuss to summarize these phenomena associated with the earthquake, its possible causes, and future directions in long term monitoring of seismogenic processes. 相似文献
124.
In order to facilitate the computations of the intensities of radiation reflected and/or transmitted by plane-parallel, vertically inhomogenous, scattering-absorbing media, we carry out the optical thickness integrations of the Cauchy systems (normally referred to as Invariant Imbedding Equations) for reflection and transmission functions originating from the first three orders of scattering: the medium in question is represented by a stack of a certain number of homogeneous slabs, each of which is characterized by a constant single scattering albedo and a constant phase function together with the optical thickness.The results are a set of recurrence formulae involving only the angular intergrations, a convenient feature for numerical computations, and should prove useful particularly for finding approximate values of the high frequency Fourier coefficients of reflection and transmission functions of inhomogeneous media or efficiently initializing the solution for a thin layer to perform rigorous multiple scattering computations by means of other techniques such as the Doubling-Adding method. 相似文献
125.
Automatic extraction of lineament information from satellite images using digital elevation data 总被引:1,自引:0,他引:1
Using conventional visual interpretation in lineament analysis presents two main problems. The first is subjectivity, introduced because of the bias of various interpreters. The second problem is that lineaments detected from satellite images are constrained by the direction of the illumination source. Since lineament identification mainly involves recognition of diagnostic morphological features, the use of digital elevation can contribute significant information about these features. Further, in generating images using digital elevation data, the direction of illumination can easily be controlled. Thus, the use of digital elevation data offers the possibility of revealing features not apparent in regular satellite images.We discuss a sequential line detection method for extraction of linear features from digital elevation data. In this method, raw elevation data is used for generating shaded relief images using the Lambertian reflection model, wherein the illumination direction is controlled by the user. The Directional Segment Detection Algorithm (DSDA) is used for detecting linear topographic features in user-defined trends. Locational information about these linear features is stored in the computer as coordinate pairs amenable to editing and subsequent analysis. Finally, three-dimensional terrain models are generated by combining the digital elevation data and satellite images. The experiments were carried out using digital elevation data of southwest Japan and Landsat MSS data. 相似文献
126.
Titanochondrodite and titanoclinohumite derived from the upper mantle in the Buell Park Kimberlite,Arizona, USA 总被引:2,自引:0,他引:2
Ken-ichiro Aoki Kiyoshi Fujino Masaki Akaogi 《Contributions to Mineralogy and Petrology》1976,56(3):243-253
Kimberlite from Buell Park, Arizona, which was intruded into Permian sediments about 30 m.y. ago, is characterized by the hydrous silicates titanochondrodite and titanoclinohumite. Titanochondrodite is the first finding in kimberlites. Optical properties, chemical compositions and cell dimensions of these two minerals are determined.Titanochondrodite and titanoclinohumite are considered to crystallize from kimberlite magma at a depth of about 100 km and at 1,000° C, on the basis of kimberlite mineralogy, petrography and high pressure experimental work. Although there is no direct evidence, the importance of these two minerals in peridotite wedges above sinking lithosphere at the continental margins is also discussed. 相似文献
127.
Kazuo Kobayashi Jean-Paul Cadet Jean Aubouin Jacques Boulgue Jacques Dubois Roland von Huene Laurent Jolivet Toshihiko Kanazawa Junzo Kasahara Kin-ichiro Koizumi Serge Lallemand Yasuo Nakamura Guy Pautot Kiyoshi Suyehiro Shin Tani Hidekazu Tokuyama Toshitsugu Yamazaki 《Earth and Planetary Science Letters》1987,83(1-4)
A detailed topographic and geophysical survey of the Daiichi-Kashima Seamount area in the southern Japan Trench, northwestern Pacific margin, clearly defines a high-angle normal fault which splits the seamount into two halves. A fan-shaped zone was investigated along 2–4 km spaced, 100 km long subparallel tracks using narrow multi-beam (Seabeam) echo-sounder with simultaneous measurements of gravity, magnetic total field and single-channel seismic reflection records. Vertical displacement of the inboard half was clearly mapped and its normal fault origin was supported. The northern and southern extensions of the normal fault beyond the flank of the seamount were delineated. Materials on the landward trench slope are displaced upward and to sideways away from the colliding seamount. Canyons observed in the upper landward slope terminate at the mid-slope terrace which has been uplifted since start of subduction of the seamount. Most of the landward slope except for the landward walls aside the seamount comprises only a landslide topography in a manner similar to the northern Japan Trench wall. This survey was conducted on R/V “Jean Charcot” as a part of the Kaiko I cruise, Leg 3, in July–August 1984 under the auspices of the French-Japanese scientific cooperative program. 相似文献
128.
Akiko Sugimoto Yukio Nobe Takafumi Yamazaki Yutaka Anzai Kiyoshi Yamagishi Yusaburo Segawa Humihiko Takei 《Physics and Chemistry of Minerals》1997,24(5):326-332
Four kinds of Cr-droped melilite crystals, Ca2MgSi2O7 (akermanite), CaAl2SiO7 (gehlenite), CaGa2SiO7 (Ga-gehlenite) and CaGa2GeO7 (GaGe-gehlenite), with different sizes of the sites for Cr ions to substitute, were grown in series, using both the CZ and
FZ techniques. Although Cr4+ is regarded as a major species in melilites, the existence of Cr6+ in gehlenite is also suggested from the change in absorption spectra by annealing, and the dependence of distribution coefficient
of Cr ions on growth atmosphere. Spectral peak shifts are not obvious if the host crystal field is altered in melilites, because
the local environment of the sites for Cr ion is possibly changed by reforming the packing features of the host lattice.
Received February 7, 1996 / Revised, accepted September 20, 1996 相似文献
129.
130.
Plastic deformation of garnets: systematics and implications for the rheology of the mantle transition zone 总被引:14,自引:0,他引:14
Shun-ichiro Karato Zichao Wang Bofa Liu Kiyoshi Fujino 《Earth and Planetary Science Letters》1995,130(1-4):13-30
Plastic properties of materials with garnet structure have been studied under wide temperature conditions, ranging from room temperature to 95% of the melting temperatures, using uniaxial compression and hot microhardness tests. Garnets studied include single crystals of oxide garnets (Y3Al5O12, Gd3Ga5O12 and Y3Fe5O12) and silicate garnets (various solid solutions, including grossular, almandine, andradite, pyrope, spessartine and uvarovite). Both uniaxial compression and hot hardness tests indicate that there is a general trend in the plasticity of garnets when the data are compared at normalized conditions (T/Tm andσ/μ), and that the resistance to plastic deformation in garnets is significantly higher than most of the other minerals in the Earth's mantle. Based on both stress-dip tests and microstructural observations, it is proposed that the creep strength of garnet is largely controlled by the resistance to dislocation glide rather than by recovery processes. This conclusion is consistent with the high Peierls stress inferred from the hot hardness tests. The high Peierls stress in garnets is, presumably, due to the large unit cell (i.e., long Burgers vectors) and/or the bcc packing, which are common to all garnets. We postulate, therefore, that the present results can be applied to the strength of high-pressure garnet (majorite) and suggest that garnet-rich layers in the Earth, such as subducted oceanic crust in the transition zone or a possibly garnet-rich (bottom part of the) transition zone, will be considerably stronger than surrounding regions. 相似文献