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Ore and Skarn Mineralogy of the Yamato Mine,Yamaguchi Prefecture,Japan, with Emphasis on Silver‐, Bismuth‐, Cobalt‐, and Tin‐bearing Sulfides 
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下载免费PDF全文 Assemblages and chemical compositions of ore minerals from the Yamato mine, Yamaguchi Prefecture, Japan, were investigated in detail to clarify its characteristics as a skarn deposit. Special attention was paid to silver‐, bismuth‐, cobalt‐, and tin‐bearing sulfide minerals and native gold at the mine, which are described here for the first time. Samples of arsenopyrite‐dominant massive ore, and garnet‐rich, clinopyroxene‐garnet‐rich, and wollastonite‐bearing skarn ores were collected from the mine dump. Arsenopyrite is the most abundant ore mineral (>80 vol.%) in the massive ore, in association with both As‐poor/free and As‐bearing pyrite. The major ore minerals in the skarn specimens are pyrite, pyrrhotite, arsenopyrite, chalcopyrite, galena, and sphalerite, along with minor argentite, Ag‐Pb‐Bi sulfate, matildite, bismuthinite, native bismuth, molybdenite, scheelite, stannite, stannoidite, cassiterite, cobaltite, gersdorffite, and Co‐rich violarite. In addition, native gold is observed in the interstices of gangue minerals. Based on the mineral assemblages and textures of the specimens examined, the major ore minerals formed in the early stage of mineralization, and the Bi‐, Ag‐, Co‐, Ni‐, As‐ and Sn‐mineralization occurred in the middle stage. Native gold was deposited in the late stage. The estimated formation temperature of the middle mineralization stage was 312±5 °C, according to iron and zinc partitioning between stannite and coexisting sphalerite. The mineralogical properties and mineralization process of the Yamato mine are consistent with those of common skarn‐ and vein‐type ore deposits associated with ilmenite‐series granitoids in the San‐yo and San‐in districts. 相似文献
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Yoji Arakawa 《Lithos》1989,24(4):261-273
The Sr isotopic compositions of Late Triassic to Early Jurassic Funatsu granitic rocks in the Hida belt, Japan, were determined and variations of the compositions within single intrusions and on a regional scale were compared with previously reported data.
Relatively low and constant (or narrow range of) initial 87Sr/86Sr ratios of granitic rocks within an intrusion (0.7044-0.7055) are found mostly in the outer part of the belt, while intrusions with high and wide ranges of initial ratios (0.7056-0.7105) are situated in the inner part. This difference in initial ratios within an intrusion is due to the different degrees of mixing between the parental mafic magma from the lower crust or upper mantle and the middle to upper crustal (or crust-derived) materials. On a regional scale, a smooth and regular increase of the ratios from 0.7044 to 0.7057, from outer to inner part, is outlined by the lowest ratio in each intrusion and this almost coincides with a trend given by the ratios of mafic rocks (or mafic enclaves) in the intrusion. This suggests a gradual change of source materials in the lower crust or upper mantle. The degree of crustal contributions to the parental magma, lesser in the outer part and larger in the inner part of the Hida belt, shows close relationships to some geophysical factors, such as the emplacement depth and uplift rate of mafic magma from deeper levels and stress state (extensional or compressional) in the middle to upper crustal levels. These factors are probably due to the plate tectonic configuration in the continental margin area where the Hida belt was included. 相似文献
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The island of Hokkaido, Japan, is subdivided into nineteen regions on the basis of regional geology and landslide distribution. Four major geologic zones characterize these regions, as follows: (1) Volcanic Rock Zone, (2) “Green Tuff” Zone, (3) Mudstone Zone, and (4) Serpentinite “Green Rock” Zone. Each zone is marked by landslides of a distinctive type. In addition, we have analyzed the relationship between landslide distribution and geologic structure for several areas. 相似文献
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Takeshi Ohmura Takeo Moriya Chengshi Piao Takaya Iwasaki Toshikastu Yoshi Shin'ichi Sakai Tetsuya Takeda Kaoru Miyashita Humihito Yamazaki Kiyoshi Ito Akira Yamazaki Yoji Shimada Katsuya Tashiro Hiroki Miyamachi 《Island Arc》2001,10(3-4):215-227
Abstract The 1995 Kobe (Hyogo-ken Nanbu) earthquake (MJMA 7.2, Mw 6.9) occurred on Jan. 17, 1995, at a depth of 17 km, beneath the areas of southern part of Hyogo prefecture and Awaji Island. To investigate P-wave velocity distribution and seismological characteristics in the aftershock area of this great earthquake, a wide-angle and refraction seismic exploration was carried out by the Research Group for Explosion Seismology (RGES) . The profile including 6 shot points and 205 observations was 135 km in length, extending from Keihoku, Northern Kyoto prefecture, through Kobe, to Seidan on Awaji Island. The charge of each shot was 350–700 kg. The P-wave velocity structure model showed a complicated sedimentary layer which is shallower than 2.5 km, a 2.5 km-thick basement layer whose velocity is 5.5 km/s, overlying the crystalline upper crust, and the boundary between the upper and lower crust.
Almost all aftershock hypocenters were located in the upper crust. However, the structure model suggests that the hypocenters of the main shock and some aftershock clusters were situated deeper than the boundary between the upper and lower crust. We found that the P-velocity in the upper crust beneath the northern part of Awaji Island is 5.64 km/s which is 3% lower than that of the surrounding area. The low-velocity zone coincides with the region where the high stress moment release was observed. 相似文献
Almost all aftershock hypocenters were located in the upper crust. However, the structure model suggests that the hypocenters of the main shock and some aftershock clusters were situated deeper than the boundary between the upper and lower crust. We found that the P-velocity in the upper crust beneath the northern part of Awaji Island is 5.64 km/s which is 3% lower than that of the surrounding area. The low-velocity zone coincides with the region where the high stress moment release was observed. 相似文献
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Sosuke Otani Yasunori Kozuki Ryoichi Yamanaka Hiromitsu Sasaoka Tetsu Ishiyama Yoshihito Okitsu Hajime Sakai Yoji Fujiki 《Estuarine, Coastal and Shelf Science》2010,86(3):434-440
The objective of this study is to elucidate the burrow structure and to clarify the role of burrows in material cycle in the tidal flat. In our work, we focused on the dominant species in muddy tidal flat, crab Macrophthalmus japonicus.Burrow structure of Macrophthalmus japonicus was investigated on a Katsuura river tidal flat in Tokushima prefecture, Japan, using in situ resin casting. Sampling was conducted in August 2006, and a total of 48 burrow casts were obtained. Burrows consisted mainly of J-shaped structures (98%) while the rest belonged to U-shaped structures (2%). The maximum measured burrow volume was 120 cm3 and wall surface area was 224 cm2, while maximum burrow length and depth were 23.2 cm and 16.5 cm, respectively. Burrow volume and surface area were strongly correlated with carapace width of M. japonicus. Investigation of the individual number of M. japonicus in 13 quadrats (50 × 50 × 20 cm) was conducted using 2 mm sieve. The number of M. japonicus was 15–31 ind./m2. Using cohort analysis we estimated that surface area of burrows was 0.07–0.15 m2/m2.CO2 emission rate was measured at the surface sediment during the period from June to December 2008. Results varied from 13.8 ± 2.2 to 49.4 ± 3.2 mg CO2/m2/h, and organic carbon decomposition was 3.8 ± 0.6–13.5 ± 0.9 mg C/m2/h. This leads the increase of organic carbon decomposition by 1.1 times, because of the expansion of the tidal flat surface area by burrowing activity. Organic carbon decomposition in burrow walls therefore contributed to organic matter decomposition in the tidal flat. These results indicated that in situ activities of Macrophthalmus japonicus significantly influence the material cycle and it is important to consider the existence of burrow in order to understand the fluxes of materials and to evaluate the purification function of the tidal flat. 相似文献
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The results of a least-squares study of the mass-luminosity relation for eclipsing and visual binary stars consisting of main sequence components are presented. Two methods are discussed. In Part A, the values of the coefficientsA andB in the relation logM=A+BM Bol are determined. Part B presents a technique which permits the determination of α and β in the relationM=αL β, when only the sum of the masses, and not the individual masses of each component, is known. The results and a comparison of the two methods are discussed. It is found that the following massluminosity relation represents the observational data satisfactorily: $$log M = 0.504 - 0.103M_{BOL,} {\text{ }} - \leqslant M_{BOL} \leqslant + 10.5$$ . A discussion of the data and of the possibility that separate mass-luminosity relations may exist for visual and eclipsing binaries is given. The possiblity that more than one mass-luminosity relation is required in the range ?8≤M Bol ≤+13 is also discussed. 相似文献
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Yoji Kondo Margherita Hack John B. Hutchings George E. McCluskey Jr. Miroslav Plavec Ronald S. Polidan 《Astrophysics and Space Science》1975,38(2):353-358
High-resolution ultraviolet spectrophotometry of the complex close binary systemβ Lyrae was performed with the Princeton Telescope Spectrometer onCopernicus. Observations were made at phases 0.0, 0.25, 0.5, and 0.75 with the resolution of 0.2 Å (far-ultraviolet) and 0.4 Å (mid-ultraviolet). The far-ultraviolet spectrum is completely dominated by emission lines indicating existence of high temperature plasma in this binary. The spectrum ofthis object is unlike any other object observed fromCopernicus. It is believed that this high temperature plasma results from dynamic mass transfer taking place in this binary. The current results are compared with the OAO-2 Wisconsin Experiment Package observations and other observational results. The possibility that the secondary component is a collapsed object is also discussed; theCopernicus observations are consistent with the hypothesis that the spectroscopically invisible secondary component is a black hole. 相似文献
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The effects on a close binary system of one component becoming a neutron star as a result of a supernova explosion are discussed in this paper. In the case of a Type I supernova, the system can remain bound in many cases of interest. For a Type II supernova, the system will probably be disrupted although in some cases a remnant of the companion to the supernova may remain in a bound orbit.Consequently, neutron stars formed in Type I supernova explosions may exist in close binary systems. Such systems may be strong X-ray emitters due to mass flow as suggested by Shklovsky. Photons with energies in the 1–50 MeV region should also be emitted. 相似文献