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101.
Summary As a part of the Japanese earthquake prediction programme, deep borehole observation of the earth's crustal activities has been planned in and around Tokyo by the National Research Center for Disaster Prevention. The first place selected was in the city of Iwatsuki, about 30 km from the centre of Tokyo. Starting in 1970, the main construction was completed at the end of 1973. The tentative observation of micro-earthquakes and crustal movement by tiltmeters has been carried out since May, 1973. As expected, noise at the bottom of the hole (3500 m depth) is extremely small, about 1/1000–1/300 of that at the surface. We could, possibly, detect earthquakes with magnitudes greater than 2.0 within 50 km radius from the Iwatsuki observatory. 相似文献
102.
Kazuo Konagai Yuanbiao Yin Yoshitaka Murono 《Soil Dynamics and Earthquake Engineering》2003,23(3):31-39
Most laterally loaded piles are flexible in the sense that they are not deformed over their entire lengths. Instead, pile deflections become negligible below an ‘active pile length’ La. This La is an important parameter that governs the overall behavior of a rigidly capped pile group. In the present approach, piles closely grouped together beneath a superstructure are viewed as a single equivalent upright beam whose stiffness matrix determines La. This idea is verified for different cases of pile spacing, and is further extended for nonlinear behavior of soils surrounding grouped piles. 相似文献
103.
Kazuo Kamura 《Environmental Geology》2002,41(5):537-546
There are many landfill sites consisting mainly of combustion residuals in Japan. The disposed materials are chemically unstable. Therefore, temporal changes of waste deposit conditions must be monitored for environmental management of landfill sites. Electrochemical properties of leachate and the relationships between the leachate properties and the resistivities of strata were studied in such landfill sites. In addition, incineration ashes immersed in distilled water were prepared and the temporal changes of electrochemical properties of the solution were examined. In composition, the ashes used in the experiment are similar to those disposed in the above sites. From the above results, the electrochemical properties of waste deposits consisting mainly of combustion residuals have been studied and the efficiency for managing landfill sites by resistivity measurements has been established. 相似文献
104.
Kazuo Konagai Muneyoshi Numada Athanasios Zafeirakos Jörgen Johansson Amir Sadr Toshihiko Katagiri 《Landslides》2005,2(2):159-163
A large number of landslides induced by the 2004 Mid Niigata Prefecture earthquake resulted in the closure of 233 segments of national and prefectural routes in Higashiyama mountain district, and 61 localities were completely isolated. Since railway and road facilities follow closely the motion of soils, damage to these facilities has to be discussed in terms of soil deformations that they experienced. The example of Kizawa tunnel shows that even relatively small soil deformations can be large enough to cause serious cracking of tunnel lining. 相似文献
105.
Abstract. Many granitic plutons of Early Cretaceous age are intruded on various scales in the Kitakami Mountains. The stock‐type Ganidake pluton accompanies enormous Fe‐Cu mineralization of the Kamaishi deposits, whereas the Kurihashi pluton accompanies less mineralization. To elucidate the cause of these differences, the metamorphic conditions and redox state of the contact metamorphic aureole around the Kurihashi pluton have been examined by the petrochemical study and gas analysis of the metamorphic rocks. A typical mineral assemblage in the pelitic rocks in the lowest‐grade part is biotite‐muscovite‐chlorite‐quartz‐plagio‐clase‐graphite, which occur more than 2 km away from the contact point with the Kurihashi pluton. Graphite disappears at the 1550 m point, and cordierite and garnet appear in the middle and highest‐grade parts, respectively. A typical mineral assemblage in the tuffaceous rocks in the lower‐grade part is chlorite‐actinolite‐biotite‐quartz‐plagioclase. Actinolite changes into hornblende near to the pluton. The CO2/CH4 ratios obtained in measurements by gas chromatography exceeds 100 in the pelitic rocks at the contact point with the pluton. The ratios decrease and become less than 0.1 with distance from the pluton. Equilibrium temperatures calculated from a garnet‐biotite pair in the pelitic rock and a hornblende‐plagioclase pair in the tuffaceous rock are 640d? and 681 d?C at the contact point, respectively. The log?o2 values among these metamorphic aureoles estimated from the CO2/CH4 ratios are slightly lower than the FMQ‐buffer. Redox states of the contact metamorphic aureole are kept in an intermediate condition between oxidized magma of the Kurihashi pluton and graphite‐bearing pelitic country rocks. Judging from these metamorphic conditions around the Kurihashi pluton and from the re‐evaluation of the previous knowledge about contact metasomatism around the Ganidake pluton, the Kurihashi metamorphism has occurred at higher temperatures and dry conditions than the Ganidake metasomatism. These differences in the metamorphic conditions and presence or absence of a large limestone mass around the pluton might be the principal reasons why the Kurihashi pluton accompanies less mineralization and the Ganidake pluton accompanies gigantic Kamaishi skarn mineralization. 相似文献
106.
107.
Evandro Luiz Klein Reginaldo Alves dos Santos Kazuo Fuzikawa Rômulo Simões Angélica 《Mineralium Deposita》2001,36(2):149-164
Fluid inclusion and structural studies were carried out at the Guarim gold deposit in the Palaeoproterozoic Tapajós province
of the Amazonian craton. Guarim is a fault-hosted gold deposit cutting basement granitoids. It consists of a quartz vein,
which is massive in its inner portions, grading laterally either to a massive or to cavity-bearing quartz vein associated
with hydrothermal breccias. The wallrock alteration comprises chlorite, carbonate, white mica and sulphide minerals, with
free gold occurring within quartz grains and spatially associated with sulphide mineral grains. Petrographic, microthermometric
and Laser Raman investigations recognised CO2-rich, mixed H2O–CO2, and H2O fluid inclusions. The coexisting CO2 and H2O–CO2 inclusions were interpreted as primary immiscible fluids that formed the gold-bearing vein. The H2O inclusions were considered a product of later infiltration of fluids unrelated to the mineralising episode. The mineralising
fluid has CO2 ranging typically from 5–10 mol%, contains traces of N2, has salinities of ∼5 wt% NaCl equiv., and densities varying between 0.85 and 0.95 g/cm3. The P–T estimations bracket gold deposition between 270–320 °C and 0.86–2.9 kb; ƒO2–ƒS2–pH estimates suggest a reduced, near-neutral character for the fluid. Variations in the physico-chemical properties, as demonstrated
by the fluid inclusion study, resulted from a combination of fluid immiscibility and pressure fluctuation. This interpretation,
combined with textural and structural evidence, suggests the emplacement of the mineralised vein in an active fault and at
a rather shallow level (4–7 km). The geological and structural setting, deposit-scale textures and structures, wallrock alteration
and physico-chemical fluid properties are compatible with those of epizonal to mesozonal orogenic lode gold deposits.
Received: 3 March 2000 / Accepted: 21 October 2000 相似文献
108.
Japan is located at the boundary between three continental and oceanic plates, and there is a great variety and complexity of geological features as a result of tectonic activities. The possibility of excavating large underground tunnels in the seemingly “fragile” rocks in orogenic areas was considered as a national project for the underground storage of petroleum. One hundred and seventy sites in 57 areas were selected based on a comprehensive survey over the whole country. After a successful experiment with a test tunnel, 112 m long and 250 m2 in cross-section area, excavated in Cretaceous granite, three sites in granites and pyroclastic rocks were selected for construction. The largest of these storage tunnels is 550 m in length and20 × 30 m in cross-section.
Before construction, a detailed survey of the subsurface geology was carried out, taking into consideration the structural geology, the mechanical properties of the rocks and the hydrogeology. It was concluded that even in active orogenic areas, there are many suitable sites for large underground excavations and that these can be detected by detailed, planned surveys. 相似文献
109.
Shinji Egathira Kazuo Ashida Associate Professor Disaster Prevention Research institute Kyoto University. Professor Disaster Prevention Research Institute Kyoto University. 《国际泥沙研究》1990,(1)
I. INTRODUCTIONArmor coats, which are comPOSed of particles coarser than those of the under layers, are usually foundon the bed surfaces of mountain streams or gravel bed rivers. A large number of P8pers have been publishedon armor coats. Most of them emphasize that the selective entrainment or transportation plays an imPOrtantrole on the armoring processes.Some recent studies indicate that the difficulty arises in describing the propagation of armor coats interms of selective entrainm… 相似文献
110.
Young kerogens isolated from seven freshwater lakes, six river mouths and four marine surface sediments were subjected to pyrolysis in vacuo. Their pyrolysates were trapped and separated subsequently for determination of hydrocarbons, fatty acids and alcohols. The abundances, carbon number distributions of long (C12) polymethylene chain lipid compounds and relative abundances of pristenes are proposed as possible indices applicable to discrimination between young kerogens from freshwater lacustrine and marine sediments. Some oil-shale kerogens of Eocene and Permian age were pyrolyzed in the same way, where the chain-length distributions of the pyrolysis products showed similar trends as those observed for the pyrolysis of young kerogens. 相似文献