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51.
Fluorine contents of some hydrous minerals derived from upper mantle and lower crust 总被引:1,自引:0,他引:1
Fluorine contents have been determined in about forty samples of amphibole, mica and apatite in alkali basalt and kimberlite and their incorporated xenoliths. They show a wide variation ranging from 15,000 to 100 ppm, corresponding to about 40 to 0.2 per cent substitution of F for OH in hydroxyl site of hydrous minerals. Fluorine abundances in these minerals reflect those of their host magmas or rocks; Itinome-gata xenoliths are the lowest and South African kimberlites and their xenoliths are the highest. F/OH and also. D/H (Kuroda et al. 1975) ratios in coexisting phlogopite-potassic richterite from peridotite and mica nodules are thoughts to have formed under no simple equlibrium conditions. 相似文献
52.
The effects of wetlands on hydrology, water quality, and wildlife habitat are internationally recognized. Protecting the remaining wetlands is one of the most important environmental issues in many countries. However wetlands in Japan have been gradually shrinking due to agricultural development and urbanization, which generally lowers the groundwater level and introduces suspended sediment and sediment-associated nutrients into wetlands. We examined the influences of channelization on discharge of suspended sediment and wetland vegetation in Hokkaido, northern Japan. The impact of river channelization was confirmed not only by the sediment budgets but also by river aggradation or degradation after the channelization and by the resultant vegetational changes. The budgets of suspended sediment demonstrated that wash load was the predominant component accounting for 95% of the total suspended load delivered into the wetland. This suspended sediment was primarily transported into the wetland by flooding associated with heavy rainfall. Twenty-three percent of the wash load and 63% of the suspended bed material load were deposited in the channelized reach, which produced aggradation of about 2 m at the end of the reach. A shorting of the length of the channel, due to channelization of a meandering river, steepened the slope and enhanced the stream power to transport sediment. This steepening shifted the depositional zones of fine sediment 5 km downstream and aggraded the riverbed. Development of the watershed may increase not only the water discharge but also the amount of suspended sediments. The aggradation reduced the carrying capacity of the channel and caused sediment ladened water to flood over the wetlands. The fine sediment accumulated on the wetlands gradually altered the edaphic conditions and wetland vegetation. A low percentage (10 to 15%) of organic contents of wetlands' soil is more evidence indicating that the present condition is far different from normal. Original vegetation such as sedges and Alnus japonica were disappearing from the adjacent areas of the river channel and were being replaced by willow trees (Salix spp.). 相似文献
53.
Tl, Ga and Ge contents of Kuroko and other types of ore deposits were analysed semiquantitatively and quantitatively. The results show that Tl content is extremely high in Kuroko-type deposits compared to other types of mineralization. The T1 content is especially high in yellow ore and pyrite crystals; thus this element is considered to be incorporated in pyrite. 相似文献
54.
Kana?NakataniEmail author Satoshi?Hayami Yoshifumi?Satofuka Takahisa?Mizuyama 《山地科学学报》2016,13(2):193-202
This paper presents debris-flow numerical simulations using the Hyper KANAKO system, developed by the authors. The system uses the debris flow simulator KANAKO 2D equipped with a graphical user interface (GUI); hence, a user can easily produce appropriate landform data for simulations using standard laser profiler data, and visualize the results using a GIS. Hyper KANAKO was applied to the streams around Kiyomizu-dera in Kyoto, Japan. Kiyomizu-dera is a famous temple in Japan which is visited by numerous tourists throughout the year. We simulated a disaster scenario of debris flow caused by torrential rain. We set the hydrograph using rainfall intensity data, and set the landform data using information from the Geospatial Information Authority of Japan (GSI) and a digital elevation model (DEM). We evaluated different mesh sizes and also used a digital surface model (DSM) to consider the building heights. The simulation results showed that with small mesh size, the debris flow moved through the roads, which seems realistic for a disaster situation. When buildings were considered, the flow direction changed, and a 1-m flow depth, which was deeper than in other cases, appeared in the flow path. This may pose a dangerous situation for evacuations. 相似文献
55.
Satoshi Sakai 《Progress in Oceanography》1986,17(3-4)
Laboratory experiments with a rotating tank confirm the bifurcation character of a barotropic flow driven by an inflow and an outflow described by Sakai (1986). The model, a circular basin with a topographic β-effect, simulates a mid-latitude oceanic feature. At a low Rossby number, stationary Rossby waves are observed which are symmetrical with a line connecting the inlet and the outlet. As the Rossby number increases, a bifurcation occurs and two kinds of vortex flows are observed. In the vortex, potential vorticity is almost uniform. In addition to the two vortex flows, a jet-like inertial flow can also be observed. In general, thre results of these experiments agree well with those of a low-order model and a numerical model. 相似文献
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59.
Satoshi Kanisawa 《Contributions to Mineralogy and Petrology》1969,20(2):164-176
The mineralogy and petrochemistry of the garnet-amphibolites from the highgrade part of the Abukuma metamorphic belt have been studied, using five analyses of rocks, five of hornblendes, three of garnets and one analysis of cummingtonite, Garnetiferous amphibolites are rich in Fe, whereas non-garnetiferous ones are rich in Mg, especially in cummingtonite-amphibolite. The chemical composition of hornblendes associated with garnet is pargasitic and rich in FeO and poor in CaO, but that of non-garnetiferous rocks is rich in MgO. The garnets are rich in almandine molecule. Mg/Mg + Fe2+ ratios of both hornblendes and garnets correspond with those of the host rocks. The development of garnet in the Adirondack metabasites belonging to the upper almandine-amphibolite and granulite facies is observed in Mg-rich rocks as well as in Fe-rich rocks, in which both garnet and hornblende are rich in Mg respectively. However, under the conditions of the andalusite-sillimanite type metamorphism as shown in the Abukuma Plateau, Fe-rich garnet occurs in Fe-rich basic rocks, but cummingtonite occurs in Mg-rich ones instead of Mg-rich garnet. Finally, the problem of polymetamorphism is discussed. The cummingtonite-amphibolite may be the product of polymetamorphism, and Mg-rich garnet which had been present previously was decomposed to cummingtonite and plagioclase by the subsequent regional metamorphism of andalusite-sillimanite type. 相似文献
60.
Overview of the MITI Nankai Trough Wells: A Milestone in the Evaluation of Methane Hydrate Resources 总被引:4,自引:0,他引:4
Yoshihiro Tsuji Hisashi Ishida Masaru Nakamizu Ryo Matsumoto Satoshi Shimizu 《Resource Geology》2004,54(1):3-10
Abstract. Bottom-simulating reflectors suggestive of the presence of methane hydrates are widely distributed below the ocean floor around Japan. In late 1999, drilling of the MITI Nankai Trough wells was conducted to explore this potential methane hydrate resource and a Tertiary conventional structure. The wells are located in the Northwest Pacific Ocean off Central Japan at a water depth of 945 m. A total of six wells were drilled, including the main well, two pilot wells, and three post survey wells at intervals of 10–100 m. All wells except the first confirmed the occurrence of hydrates based on logging-while-drilling, wire-line logging and/or coring using a pressure and temperature coring system in addition to conventional methods. Based on the various well profiles, four methane hydrate-bearing sand-rich intervals in turbidite fan deposits were recognized. Methane hydrates fill the pore spaces in these deposits, reaching saturation of up to 80 % in some layers. The methane hydrate-bearing turbiditic sand layers are less than 1 m thick, with a total thickness of 12–14 m. The bottom depth of high hydrate concentration correlates well with the depth of the bottom-simulating reflector. Based on these exploration results, the Japanese government inaugurated a 16-year methane hydrate exploitation program in 2001. 相似文献