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81.
A Late Cretaceous mammalian dentary from the Ashizawa Formation (Futaba Group), Fukushima,northeastern Japan 下载免费PDF全文
A mammalian dentary discovered in the Coniacian Ashizawa Formation (Fukushima, northeastern Japan) is described. The specimen is a fragment of the horizontal ramus of a left edentulous dentary with five alveoli, the distal four of which are plugged with broken roots. Based on the morphologies of the dentary and the roots, it is considered to be of a therian mammal. This constitutes the first discovery of a Mesozoic mammal in northeastern Japan and highlights the potential for future mammal discoveries in the Cretaceous System in northeastern Japan, which will be significant for disclosure of the mammalian faunal evolution in East Asia during the Late Cretaceous. 相似文献
82.
Chemical characteristics of chromian spinel in plutonic rocks: Implications for deep magma processes and discrimination of tectonic setting 总被引:2,自引:0,他引:2
Shoji Arai Hidenobu Okamura Kazuyuki Kadoshima Chima Tanaka Kenji Suzuki Satoko Ishimaru 《Island Arc》2011,20(1):125-137
We summarize chemical characteristics of chromian spinels from ultramafic to mafic plutonic rocks (lherzolites, harzburgites, dunites, wehrlites, troctolites, olivine gabbros) with regard to three tectonic settings (mid‐ocean ridge, arc, oceanic hotspot). The chemical range of spinels is distinguishable between the three settings in terms of Cr# (= Cr/(Cr + Al) atomic ratio) and Ti content. The relationships are almost parallel with those of chromian spinels in volcanic rocks, but the Ti content is slightly lower in plutonics than in volcanics at a given tectonic environment. The Cr# of spinels in plutonic rocks is highly diverse; its ranges overlap between the three settings, but extend to higher values (up to 0.8) in arc and oceanic hotspot environments. The Ti content of spinels in plutonics increases, for a given lithology, from the arc to oceanic hotspot settings by mid‐ocean ridge on average. This chemical diversity is consistent with that of erupted magmas from the three settings. If we systematically know the chemistry of chromian spinels from a series of plutonic rocks, we can estimate their tectonic environments of formation. The spinel chemistry is especially useful in dunitic rocks, in which chromian spinel is the only discriminating mineral. Applying this, discordant dunites cutting mantle peridotites were possibly precipitated from arc‐related magmas in the Oman ophiolite, and from an intraplate tholeiite in the Lizard ophiolite, Cornwall. 相似文献
83.
Akio Suzuki Eiji Ohtani Hidenori Terasaki Keisuke Nishida Hiromi Hayashi Tatsuya Sakamaki Yuki Shibazaki Takumi Kikegawa 《Physics and Chemistry of Minerals》2011,38(1):59-64
The viscosity of a silicate melt of composition NaAlSi2O6 was measured at pressures from 1.6 to 5.5 GPa and at temperatures from 1,350 to 1,880°C. We employed in situ falling sphere
viscometry using X-ray radiography. We found that the viscosity of the NaAlSi2O6 melt decreased with increasing pressure up to 2 GPa. The pressure dependence of viscosity is diminished above 2 GPa. By using
the relationship between the logarithm of viscosity and the reciprocal temperature, the activation energies for viscous flow
were calculated to be 3.7 ± 0.4 × 102 and 3.7 ± 0.5 × 102 kJ/mol at 2.2 and 2.9 GPa, respectively. 相似文献
84.
Koji Sugie Kenshi Kuma Satoshi Fujita Satomi Ushizaka Koji Suzuki Tsutomu Ikeda 《Journal of Oceanography》2011,67(2):183-196
We report on the ability for luxury Fe uptake and the potential for growth utilizing intracellular Fe pools for 4 coastal
centric diatom isolates and in situ phytoplankton assemblages, mainly composed of diatoms. Iron uptake of the diatom isolates
and natural phytoplankton assemblages in the Oyashio region during spring blooms were prevented by adding hydroxamate siderophore
desferrioxamine B (DFB). After the addition of DFB, intracellular Fe in the diatom isolates supported 2.4–4.2 cell divisions
with 1.2–2.6 Chl a doublings. The intracellular Fe was primarily used for cell generation rather than Chl a production, leading to a reduction in the Chl a cell quota in the Fe-starved cells with time. The metabolic properties of the Fe-starved cells with their cell morphologies
were different among species or genera. An on-deck incubation experiment also exhibited 1.9 cell divisions and 0.81 Chl a doublings of phytoplankton after the addition of DFB, also indicating the preference of cell generation over Chl a production. A decrease in the level of cellular Chl a, a main light-harvesting pigment in Fe-starved diatoms, may become a superior survival strategy to protect the cells from
high irradiance that can cause photo-oxidative damages through photosynthesis. Such relatively low-Fe with high-light conditions
could often occur in surface waters of the Oyashio region from spring to summer. 相似文献
85.
Hisanari Sugawara Masayuki Sakakibara David Belton Tetsuya Suzuki 《Environmental Earth Sciences》2013,69(3):811-819
Pyrite framboid in sedimentary rocks could be concerned with arsenic contamination in groundwater of acidic environment and has been studied for the formation process of its unique morphology. However, not much has been discussed about the formation process based on the heavy-metal distribution in pyrite framboids and their aggregates. To reveal the formation process of pyrite framboids and their aggregates, mudstone from the Late Cretaceous Hakobuchi Group, central Hokkaido, Japan, are investigated for mode, petrographical, mineralogical, and micro-PIXE (particle-induced X-ray emission) analysis in this study. Spherical and sub-spherical pyrite framboids observed in polyframboids can be divided into two types based on the diameter of framboids (D) and the average diameter of microcrystals (d) within framboids: type 1, ranging from 2 to 9 μm and from 0.4 to 0.9 μm, respectively, and type 2, ranging from 8 to 50 μm and from 0.5 to 1.8 μm, respectively. Based on the quantitative traverse analyses and 2-D elemental mapping results by micro-PIXE, heterogeneities in the concentrations of heavy metals within the analyzed aggregations of pyrite are exhibited. On the basis of the As and Pb zoning patterns, the time range and chronological stages of pyrite-aggregation growth are revealed. 相似文献
86.
K. Myokei Y. Matsudo T. Asano T. Suzuki Y. Hobara K. Michimoto M. Hayakawa 《Journal of Atmospheric and Solar》2009,71(5):597-602
Continuous observations of sprites in the Hokuriku area of Japan were performed from two optical sites during the three winter periods. The purpose of this observation is to study the major effect in the appearance of sprites and in determining the morphology of sprites (columns or carrots). Detailed analysis is performed based on the estimation of the height of ?10 °C at the time of sprite occurrence. When the height of ?10 °C is lower than 1800 m, the occurrence of sprites is infrequent, and the dominant shape is column. Then when it is increased (1800–3000 m), a new situation takes place, namely the occurrence of sprites is very enhanced and more spectacular shapes like carrots tend to be frequently observed in addition to column sprites. These sprite characteristics are first compared with those of parent lightning in the Hokuriku area and with our latest computer simulations on sprite initiation. 相似文献
87.
Three-dimensional EM computer simulation on sprite initiation above a horizontal lightning discharge
The purpose of this paper is to study the three-dimensional (3D) effects of the source current and the electromagnetic (EM) pulse on the distribution of upper atmospheric electric field and ionization created. A new lightning model has been employed; i.e., we have included a horizontal channel in addition to the conventional vertical channel. The effects of the horizontal lightning channel are summarized as follows: (1) the effect of a vertical channel plays a fundamental role in the whole view of sprite initiation; (2) the position of a sprite is shifted from the position of its parent vertical channel in response to the length of a horizontal channel; and (3) we observe very fine structures with local maxima and minima in the “reduced” electric field (the electric field divided by the neutral gas density). These theoretical inferences are discussed and compared with the observational facts so far reported (such as lateral shift of sprites, morphological difference of sprites, etc.). 相似文献
88.
89.
It is fact that the severe ground motions of shear waves have a strong effect on the dynamic behavior of buildings and civil structures. We simulate near source strong motions of a pure shear wave and synthesize small motions, using the parameters based on the recorded accelerograms at the site that is regarded as a base rock in the Osaka basin, Japan. By making use of a stochastic technique, we can easily introduce higher frequency contents in the motions and apply the technique to the synthesis of small waves regarding as a green function. We also introduce to the analysis the useful relationships among the time duration Td, the seismic moment M0, the corner frequency fc and the high cutoff frequency fmax which were regressed by a simple representation scheme. Considering two active faults that may affect severe damage on buildings and civil structures, we try to predict strong ground motions in Osaka basin and show the characteristics of them. 相似文献
90.
Saito S Yamamoto S Irvine WM Ziurys LM Suzuki H Ohishi M Kaifu N 《The Astrophysical journal》1988,334(2):L113-L116
An asymmetric-top free radical CH2CN, which as a 2B1 ground state, was detected for the first time by laboratory microwave spectroscopy. The radical was produced in a free-space absorption cell by a DC glow discharge in pure CH3CN gas. About 60 fine-structure components were observed for the N = 11-10 to 14-13 a-type rotational transitions in the frequency region of 220-260 GHz, and many hyperfine resolved components for the N = 4-3 and 5-4 transitions in the 80 and 100 GHz regions, respectively. The molecular constants, including the rotational constants, centrifugal distortion constants, and spin-rotation coupling constants with centrifugal distortion correction terms were determined from the fine-structure resolved transitions, and the hyperfine coupling constants due to the hydrogen and nitrogen nuclei were obtained from the low-N transitions. As a result we assigned U100602 and U80484 from Sgr B2, and U40240 and U20120 from TMC-1, to the N = 5-4, 4-3, 2-1, and 1-0 transitions with K-1 = 0 of the CH2CN radical. 相似文献