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排序方式: 共有400条查询结果,搜索用时 312 毫秒
31.
Mitsuhiko Hayashi Ichiro Tamura Osamu Shimomura Hiroshi Sawamoto Haruki Kawamura 《Physics and Chemistry of Minerals》1987,14(4):341-344
Néel temperature (Tm N of α-Fe2SiO4 (fayalite) was measured as a function of pressure by means of Mössbauer spectroscopy in the pressure range 0–16 Gpa. High pressure was generated using a clamp-type miniature diamond anvil cell which was inserted into a cryostat. The Néel temperature increased linearly with increasing pressure at a rate of dT N /dp=2.2±0.2 K/GPa. The result is discussed on the basis of the model proposed for the magnetic structure of fayalite by Santoro et al. (1966). The observed dT N /dp suggests that the superexchange interactions vary as the ?10/3 power of the volume while the volume dependence of the direct exchange interactions is positive and small. 相似文献
32.
Osamu Ujike 《Lithos》1982,15(4):281-287
A compositional gap between hypersolidus plagioclase and subsolidus plagioclase, most of which must have formed by devitrification, decreases in An % with decreasing cooling rate, probably reflecting a melt composition derived by in situ differentiation. Augitic pyroxenes, crystallized from a quickly cooling magma, tend to contain more Al, Ti, Na(+K) and Fe3+, and less Si and Mn. Compositional breaks between hypersolidus and subsolidus amphiboles with respect to the components of edenite and titanoamphibole, decrease in width with decreasing cooling rate. Subcalcic hornblende seems to grow from differentiated magmas in the course of moderate to rapid cooling. 相似文献
33.
Analysis of vertical crustal deformation data in the southwestern part of Shikoku, southwest Japan, suggests that the Nankaido earthquake of 1946 (Mw = 8.1), which is a principal interplate thrust earthquake, was accompanied by subsidiary faulting on a splay fault adjacent to the coast of Shikoku. Discarding crustal movement resulting from the main thrusting of the Nankaido earthquake, local leveling data are explained by slip on a simple rectangular thrust fault located just offshore of Shikoku. Although it is difficult to constrain the fault location, a possible result is a high-angle thrust dipping landward at an angle of about 70°, with a dislocation of about 1.5 m, and source dimensions of 30 × 13 km along strike and dip. respectively. This result indicates that the fault may be one of the steeply dipping subsidiary faults branching from the main low-angle thrust, as was the case in the Alaska earthquake of 1964. Although several lines of evidence suggest that this faulting occurred as slow aseismic slip, its discrimination from the main seismic event is extremely difficult. This kind of high-angle thrusting just offshore of the coast would play an important role for the formation of the marine terraces during the late Quaternary period. 相似文献
34.
Naoyuki Kato 《Geophysical Journal International》2007,168(2):797-808
35.
Tsunami deposits provide a basis for reconstructing Holocene histories of great earthquakes and tsunamis on the Pacific Coast
of southwest Japan. The deposits have been found in the past 15 years at lakes, lagoons, outcrops, and archaeological excavations.
The inferred tsunami histories span 3000 years for the Nankai and Suruga Troughs and nearly 10,000 years for the Sagami Trough.
The inferred histories contain recurrence intervals of variable length. The shortest of these —100–200 years for the Nankai
Trough, 150–300 years for the Sagami Trough — resemble those known from written history of the past 1000–1500 years. Longer
intervals inferred from the tsunami deposits probably reflect variability in rupture mode, incompleteness of geologic records,
and insufficient research.
The region's tsunami history could be clarified by improving the geologic distinction between tsunami and storm, dating the
inferred tsunamis more accurately and precisely, and using the deposits to help quantify the source areas and sizes of the
parent earthquakes. 相似文献
36.
日本南海海槽天然气水合物研究现状 总被引:8,自引:3,他引:8
本文介绍日本在其周围海域特别是南海海槽的海洋天然气水合物研究工作,首先介绍其研究简史,研究计划,研究队伍及早期研究成果,其次,介绍了西南海海槽天然气水合物的勘探、研究状况,然后,介绍了五年计划实施的东南海海槽地球物理勘探、钻探状况,最后指出,南海海槽的一些新资料深入的综合研究无疑会给世界水合物研究增添新的内容。 相似文献
37.
38.
Victor B. MAGLAMBAYAN Daizo ISHIYAMA Toshio MIZUTA Osamu MATSUBAYA Yohei ISHIKAWA 《Resource Geology》2001,51(2):107-116
Abstract: The disseminated Au‐Ag telluride Bulawan deposit, Negros island, Philippines, is hosted by dacite porphyry breccia pipes which formed in a Middle Miocene dacite porphyry stock. Electrum and Au‐Ag tellurides occur mostly as grains intergrown with or filling voids between sphalerite, pyrite, chalcopyrite, galena and tennantite. Calcite, quartz and rare dolomite are the principal gangue minerals. Four types of alteration were recognized in the deposit, namely; propylitic, K‐feldspar‐sericitic, sericitic and carbonate alteration. Carbonate alteration is correlatable to the gold deposition stage and occurs mostly along fault zones. The δ18O and δ13C compositions of calcite and dolomite in propylite zone and ore‐stage dacite porphyry breccia were determined. The δ18O values of calcite in propylitized andesite range from +12.2 to +14.7%, and their δ13C values range from ‐6.1 to ‐1.0%. The δ18O values of calcite and dolomite in sericite‐ and carbonate‐altered, mineralized dacite porphyry breccia and dacite porphyry rocks range from +15.1 to +23.1%, and the δ13C values of calcite and dolomite range from ‐3.9 to +0.9%. The δ18O and δ13C values of the hydrothermal fluids were estimated from inferred temperatures of formation on the basis of fluid inclusion microthermometry. The δ18O values of hydrothermal fluid for the propylitic alteration were calculated to be +8.5 ‐ +9.5%, assuming 375°C. On the other hand, the δ18O values of ore solutions for base metal and Au mineralization were computed to be +13.6 ‐ +14.6%, assuming 270°C. The hydrothermal fluids that formed the Bulawan deposit are dilute and 18O‐enriched fluids which reacted with 18O‐ and 13C‐rich wallrocks such as limestone. 相似文献
39.
Tadashi Kondo Hiroshi Sawamoto Akira Yoneda Manabu Kato Akihito Matsumuro Takehiko Yagi Takumi Kikegawa 《Pure and Applied Geophysics》1993,141(2-4):601-611
A new multi-anvil type high-presure apparatus has been developed using sintered diamond anvils to generate pressures over 30 GPa and temperatures up to about 2000°C. A maximum sample volume of about 1 mm3 is available in this system. The pressure was confirmed by dissociation of forsterite into Mg-perovskite and periclase. The basic techniques and problems in utilizing sintered diamond in the MA8 type high-pressure apparatus are discussed with an emphasis on the future prospect of incorporating simultancous X-ray diffraction observation. 相似文献
40.
Convective instability and overstability of a plane-parallel medium in the presence of a uniform vertical magnetic field is studied. We take into account both the effect of penetration of disturbances into sub-adiabatically stratified semi-infinite upper and lower layers, and the effect of thermal damping of disturbances introduced by the compressibility of the medium. If the degree of super-adiabaticity in temperature stratification in the middle layer is relatively large compared with that of sub-adiabaticity in the upper and lower layers, the range of physical conditions in which overstable convection occurs is very narrow. However, if it is not the case the range is rather wide. In the normal sunspot umbra, only disturbances with selected sizes in vertical dimension will be able to become overstable. The overstable convection might be a cause of some dynamical features (such as dots) in the sunspot umbra, but will not be the main contributor for transporting mechanical energy in the sunspot region. 相似文献