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21.
The slowly varying components (S-components) of the solar radio emission were observed by a 17 Gc/s grating interferometer. In combination with 4 Gc/s data, it is deduced that the source of the 17 Gc/s S-component is optically thin. 相似文献
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Yuki Shibazaki Eiji Ohtani Hidenori Terasaki Ryuji Tateyama Tatsuya Sakamaki Taku Tsuchiya Ken-ichi Funakoshi 《Earth and Planetary Science Letters》2011,301(1-2):153-158
We have carried out in situ X-ray diffraction experiments on the FeS–H system up to 16.5 GPa and 1723 K using a Kawai-type multianvil high-pressure apparatus employing synchrotron X-ray radiation. Hydrogen was supplied to FeS from the thermal decomposition of LiAlH4, and FeSHx was formed at high pressures and temperatures. The melting temperature and phase relationships of FeSHx were determined based on in situ powder X-ray diffraction data. The melting temperature of FeSHx was reduced by 150–250 K comparing with that of pure FeS. The hydrogen concentration in FeSHx was determined to be x = 0.2–0.4 just before melting occurred between 3.0 and 16.5 GPa. It is considered that sulfur is the major light element in the core of Ganymede, one of the Galilean satellites of Jupiter. Although the interior of Ganymede is differentiated today, the silicate rock and the iron alloy mixed with H2O, and the iron alloy could react with H2O (as ice or water) or the hydrous silicate before the differentiation occurred in an early period, resulting in a formation of iron hydride. Therefore, Ganymede's core may be composed of an Fe–S–H system. According to our results, hydrogen dissolved in Ganymede's core lowers the melting temperature of the core composition, and so today, the core could have solid FeSHx inner core and liquid FeHx–FeSHx outer core and the present core temperature is considered to be relatively low. 相似文献
24.
Toshio Tsuchiya 《Astrophysics and Space Science》2003,284(2):515-518
Dynamical evolution of galactic disks driven by interaction with satellite galaxies, particularly the problem of the disk
warping and thickening is studied numerically. One of the main purpose of the study is to resolve the long standing problem
of the origin of the disk warping. A possible cause of the warp is interaction with a satellite galaxy. In the case of the
Milky Way, the LMC has been considered as the candidate. Some linear analysis have already given a positive result, but one
had to wait for a fully self-consistent simulation as a proof. I have accomplished the numerical simulations with a million
particles, by introducing a hybrid algorithm, SCF-TREE. Those simulations give us quantitative estimates for the Milky Way
system. We have found an example in which large warp amplitudes are developed. We also found that the warp amplitudes depend
on the halo distribution. Among our three models, the most massive and spherical halo is preferable for the observable warp
excitation.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
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The postperovskite phase transition of Fe and Al-bearing MgSiO3 bridgmanite, the most aboundant mineral in the Earth's lower mantle, is believed to be a key to understanding seismological observations in the D″ layer, e.g., the discontinuous changes in seismic wave velocities. Experimentally reported phase transition boundaries of Fe and Al-bearing bridgmanite are currently largely controversial and generally suggest wide two-phase coexistence domains. Theoretical simulations ignoring temperature effects cannot evaluate correctly two-phase coexistence domains under high-temperature. We show high-pressure and high-temperature phase transition boundaries for various compositions with geophysically relevant impurities of Fe2+SiO3, Fe3+Fe3+O3, Fe3+Al3+O3, and Al3+Al3+O3 derived from the ab initio finite-temperature free energies calculated combining the internally consistent LSDA + U method and a lattice dynamics approach. We found that at ~ 2500 K, incorporations accompanied by Fe3+ expand the two-phase coexistence domains distinctly, implying that D″ seismic discontinuities likely arise from the phase transition of Fe2+-bearing bridgmanite. 相似文献
27.
INTRODUCTIONCiliates,alwaysdominatingalltheprotozoans,arethecommonandimportantmembersoffreshwaterzooplanktoncommunities.Asmainconsumersofbacteria,picoplanktonandnannoplankton(Finlay,1978;Porteretal.,1985;Taylor,1984,1987;Simeketal.,1996)compriseanimportanttrophiclinka… 相似文献
28.
Geologic Core Holder with a CFR PEEK Body for the X-ray CT-Based Numerical Analysis of Fracture Flow Under Confining Pressure 总被引:1,自引:0,他引:1
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U. Burenjargal A. Okamoto T. Kuwatani S. Sakata T. Hirata N. Tsuchiya 《Journal of Metamorphic Geology》2014,32(7):765-790
The timing and thermal effects of granitoid intrusions into accreted sedimentary rocks are important for understanding the growth process of continental crust. In this study, the petrology and geochronology of pelitic gneisses in the Tseel area of the Tseel terrane, SW Mongolia, are examined to understand the relationship between igneous activity and metamorphism during crustal evolution in the Central Asian Orogenic Belt (CAOB). Four mineral zones are recognized on the basis of progressive changes in the mineral assemblages in the pelitic gneisses, namely: the garnet, staurolite, sillimanite and cordierite zones. The gneisses with high metamorphic grades (i.e. sillimanite and cordierite zones) occur in the central part of the Tseel area, where granitoids are abundant. To the north and south of these granitoids, the metamorphic grade shows a gradual decrease. The composition of garnet in the pelitic gneisses varies systematically across the mineral zones, from grossular‐rich garnet in the garnet zone to zoned garnet with grossular‐rich cores and pyrope‐rich rims in the staurolite zone, and pyrope‐rich garnet in the sillimanite and cordierite zones. Thermobarometric analyses of individual garnet crystals reveal two main stages of metamorphism: (i) a high‐P and low‐T stage (as recorded by garnet in the garnet zone and garnet cores in the staurolite zone) at 520–580 °C and 4.5–7 kbar in the kyanite stability field and (ii) a low‐P and high‐T stage (garnet rims in the staurolite zone and garnet in the sillimanite and cordierite zones) at 570–680 °C and 3.0–6.0 kbar in the sillimanite stability field. The earlier high‐P metamorphism resulted in the growth of kyanite in quartz veins within the staurolite and sillimanite zones. The U–Pb zircon ages of pelitic gneisses and granitoids reveal that (i) the protolith (igneous) age of the pelitic gneisses is c. 510 Ma; (ii) the low‐P and high‐T metamorphism occurred at 377 ± 30 Ma; and (iii) this metamorphic stage was coeval with granitoid intrusion at 385 ± 7 Ma. The age of the earlier low‐T and high‐P metamorphism is not clearly recorded in the zircon, but probably corresponds to small age peaks at 450–400 Ma. The low‐P and high‐T metamorphism continued for c. 100 Ma, which is longer than the active period of a single granitoid body. These findings indicate that an elevation of geotherm and a transition from high‐P and low‐T to low‐P and high‐T metamorphism occurred, associated with continuous emplacement of several granitoids, during the crustal evolution in the Devonian CAOB. 相似文献