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71.
Structure refinement was carried out on a nonstoichiometric clinopyroxene grown under the ambient pressure from a glass with
composition of 23%(mol)Di+53%Es+24%An. The degree of nonstoichiometry in this crystal is significantly larger than those of
clinopyroxenes reported previously, which were found in high pressure products. The refinement gave the empirical chemical
formula (Ca0.742Fe0.087)(Mg0.016Al0.888Fe0.075)(Al0.500Si1.500)O6 for the crystal and showed that vacancies are located mainly at M2 sites. Despite replacement of Si by Al, the crystal has
a smaller cell volume than diopside primarily owing to a significant amount of Mg at M1 being replaced by Al.
Received: 25 June 1997 / Revised, accepted: 6 September 1997 相似文献
72.
Time variation of the cold water mass of the Kuroshio south of Japan, which was formed in August 1975 and disappeared in August 1980, is studied. Its lifecycle includes several repetitions of spin-down and spin-up processes. The spin-down (or the spin-up) process is accompanied by warming (cooling) of the cold water mass and descending (ascending) motion of the inner water. Expansion of the cold water area is also associated with the spin-up period while shrinking occurs in the spin-down period. The rate of spin-down of the cold water mass is approximately equal to that of the Gulf Stream rings. The spin-up process is not observed in the Gulf Stream rings and the longer lifetime of the cold water mass off Japan, in comparison with the Gulf Stream rings, is due to the existence of the spin-up periods. The spin-up process tends to occur in late spring to summer, and it seems to be related to the seasonal variation in intensity of the Kuroshio. 相似文献
73.
Sotaro Takano Makoto Ito Takanori Nakano Keiji Horikawa Yuzuru Nakamura Takahiro Saito 《Sedimentary Geology》2004,170(3-4):189-206
Sequence-stratigraphic signatures of hemipelagic siltstones were investigated using profiles of the magnetic susceptibility and selected chemical composition of the Early Pleistocene deep-water successions of the Kiwada and Otadai Formations on the Boso Peninsula, Japan. In the context of an independently developed sequence-stratigraphic framework for the submarine-fan deposits of the Otadai Formation, the magnetic susceptibility and chemical composition, such as the concentrations of TiO2, MgO and Fe2O3, show that the lowstand systems tract deposits have higher values of these parameters than the transgressive and highstand systems tract deposits. In contrast, the CaO contents have inverse relationships with the magnetic susceptibility and are higher in the transgressive and highstand systems tract deposits. The positions of sequence boundaries largely coincide with the horizons from which the magnetic susceptibility and the contents of mafic component increase abruptly. The sequence-stratigraphic variations in the magnetic susceptibility and chemical composition of the submarine-fan hemipelagic siltstones are due to increases in the input of fine-grained, terrigenous clastic sediments from midwater flow suspension, in addition to the direct fluvial supply of relatively unmodified terrigenous clastic sediments during relative sea-level lowstands, although grain size of hemipelagic siltstones does not exhibit any distinct variation through depositional sequences. The Kiwada Formation is characterized by siltstone-dominated basin-plain deposits and its sequence-stratigraphic classification has been difficult when using just lithofacies features. Nevertheless, the profiles of the magnetic susceptibility and chemical composition of the basin-plain deposits are similar to those of the submarine-fan deposits with duration largely equivalent to the 41,000-years obliquity cycle of the Early Pleistocene oxygen isotope sea-level index. This finding indicates that the profiles of the magnetic susceptibility and chemical composition of hemipelagic siltstones reflect sequence-stratigraphic variation in the input of fine-grained terrigenous clastic sediments to the deep-water environments and are crucial for the recognition of cryptic sequence boundaries in hemipelagic successions. 相似文献
74.
Subrata Ghose Fujio P. Okamura Haruo Ohashi 《Contributions to Mineralogy and Petrology》1986,92(4):530-535
The crystal structure of a synthetic CaFe3+Al-SiO6 pyroxene (20 kb, 1,375° C) with unit cell dimensions a=9.7797(16), b=8.7819(14), c=5.3685(5) Å, =105.78(1), space group C2/c has been refined by the method of least squares to an R-factor of 0.025 based on 812 reflections measured on an automatic single crystal diffractometer. The octahedral M1 site is occupied by 0.82 Fe3+ and 0.18 Al3+. Within the tetrahedral T site, Si4+ (0.50), Al3+ (0.41) and Fe3+ (0.09) ions are completely disordered, although submicroscopic domains with short-range order are very likely. The octahedral site preference energy of the Fe3+ ions with respect to Al3+ ions in CaFe3+AlSiO6 is about 10 kcal/mole, which is much higher than that found in Y3Al
x
Fe5–2O12 garnets. Topologically the structure of CaFe3+AlSiO6 is intermediate between that of diopside and calcium Tschermak's pyroxene, CaAlAlSiO6. For CaM3+ AlSiO6 clinopyroxenes an increase in the size of the M1 octahedron is accompanied by an increase in the average M2-0, bridging T-0 and 03-03 distances and kinking of the tetrahedral chain. 相似文献
75.
Yoshimasu Kuroda Tetsuro Suzuoki Sadao Matsuo Haruo Shirozu 《Contributions to Mineralogy and Petrology》1976,57(2):223-225
Chemistry dependence of D of chlorites is inferred from data for natural chlorites. D of water equilibrated with those chlorites is estimated to be –2–8. 相似文献
76.
Fabrizio Nestola Tiziana Boffa Ballaran Haruo Ohashi 《Physics and Chemistry of Minerals》2008,35(8):477-484
Two synthetic single-crystals with composition Li(Al0.53Ga0.47)Si2O6 and LiGaSi2O6 and space group C2/c at room conditions have been studied under pressure by means of X-ray diffraction using a diamond anvil cell. The unit-cell
parameters were determined at 12 and 10 different pressures up to P = 8.849 and P = 7.320 GPa for Li(Al0.53Ga0.47)Si2O6 and LiGaSi2O6, respectively. The sample with mixed composition shows a C2/c to P21/c phase transformation between 1.814 and 2.156 GPa, first-order in character. The transition is characterised by a large and
discontinuous decrease in the unit-cell volume and by the appearance of the b-type reflections (h + k = odd) typical of the primitive symmetry. The Ga end-member shows the same C2/c to P21/c transformation at a pressure between 0.0001 and 0.39 GPa. The low-pressure value at which the transition occurred did not
allow collecting any data in the C2/c pressure stability field except that on room pressure. Our results compared with those relative to spodumene (LiAlSi2O6, Arlt and Angel 2000a) indicate that the substitution of Al for Ga at the M1 site of Li-clinopyroxenes strongly affects the transition pressure
causing a decrease from 3.17 GPa (spodumene) to less than 0.39 GPa (LiGaSi2O6) and decreases the volume discontinuity at the transition. As already found for other compounds, the C2/c low-pressure phases are more rigid than the P21
/c high-pressure ones. Moreover, the increase of the M1 cation radius causes a decrease in the bulk modulus K
T0. The axial compressibility among the Li-bearing clinopyroxenes indicates that the c axis is the most rigid for the C2/c phases while it becomes the most compressible for the P21
/c phases. 相似文献
77.
78.
Hiroshi Kinoshita Haruo Yoshida Hiroshi Nakai 《Celestial Mechanics and Dynamical Astronomy》1990,50(1):59-71
Symplectic integrators have many merits compared with traditional integrators: 相似文献
79.
80.
Ando Haruo Maki Hideaki Kashiwagi Nobuhisa Ishii Yuuichi 《Journal of Oceanography》2021,77(6):843-858
Journal of Oceanography - Long-term trends of bottom-water concentrations of dissolved oxygen (DO), total nitrogen, and total phosphorus at 42 sites in Tokyo Bay were analyzed using monthly data... 相似文献