Variations of Raman spectra of MgSiO3·10% Al2O3-perovskite were investigated up to about 270 kbar at room temperature and in the range 108–425 °K at atmospheric pressure. Like MgSiO3-perovskite, the Raman frequencies of MgSiO3·10% Al2O3-perovskite increase nonlinearly with increasing pressure and decrease linearly with increasing temperature within the experimental uncertainties and the range investigated. A comparison of these data with those of MgSiO3-perovskite suggests that MgSiO3·10% Al2O3-perovskite is slightly more compressible than MgSiO3-perovskite, and that the volume thermal expansion for MgSiO3·10% Al2O3-perovskite is also slightly greater than that for MgSiO3-perovskite. 相似文献
This study is a broad-scale synthesis of information on climate changes in two Arctic terrestrial regions, eastern Siberia and the Alaska–Yukon area of North America. Over the past 60 years (1951–2010), the trends of temperature and precipitation in the two regions are broadly similar in their seasonality. However, atmospheric advection influences the two regions differently during winter. The differential advective effects are much weaker in the other seasons. The Pacific Decadal Oscillation is the strongest correlator with interannual variability in the two regions, followed by the Arctic Oscillation and the El Niño/Southern Oscillation.Projected changes by the late 21st Century are qualitatively similar to the changes that have been ongoing over the past 60 years, although the rate of change increases modestly under mid-range forcing scenarios (e.g., the A1B scenario). The greatest warming is projected to occur farther north over the Arctic Ocean in response to sea ice loss. Precipitation is projected to increase by all models, although increases in evapotranspiration preclude conclusions about trends toward wetter or drier land surface conditions. A notable feature of the future climate simulations is a strong maximum of pressure decreases in the Bering Sea region, implying further advective changes. 相似文献
Summary. The luni-solar forced nutations and body tide are believed to be resonant at frequencies near (1 + 1/460) cycle sidereal day−1 as seen from the rotating Earth. This resonance is due to the Earth's rotating, elliptical fluid core. We show here that tides in the open ocean and the Earth's response to those tides must also be resonant at (1 + 1/460) cycle day−1. We examine these resonant oceanic effects on the Earth's nutational motion and on the body tide. Effects on the forced nutations might be as large as 0.002 arcsec at 18.6 yr. The effects on the observed resonance in the body tide are more important. For tidal gravity, for example, the difference between K 1 and 0 1 which is usually used to determine the resonance, can be perturbed by 30 per cent or more due to the oceanic resonance effects. 相似文献
The Kurosegawa zone in southwest Japan is a 600 km long serpentinite mélange in the Chichibu terrains. It runs generally E-W but is slightly oblique to the subparallel arrangement of the Ryoke, Sanbagawa and Chichibu belts of Southwest Japan. A variety of geological units occurs in the Kurosegawa zone:
1. (1) granodiorite, gneiss and amphibolite of ca. 400 Ma,
2. (2) Siluro-Devonian formations,
3. (3) Upper Carboniferous to Jurassic formations,
4. (4) Upper Jurassic to Lower Cretaceous formations,
5. (5) serpentinite and
6. (6) low- to medium-grade metamorphic rocks of various baric types (ages, 220, 320, 360 and 420 Ma by K-Ar).
The most widespread is a high-pressure intermediate group of metamorphic rocks. Serpentinite is emplaced along the faults between and within the constituent units.Rocks of the Kurosegawa zone represent a mature orogenic belt along a continental margin or an island arc. Its original site as constrained by paleomagnetism was near the equatorial area. Here, 400 Ma old paired metamorphism and related magmatism took place. The island arc or microcontinent migrated northward to collide with the Eurasia plate during Late Jurassic, thus consuming the intervening ocean. 相似文献
The stability field of knorringite (Mg3Cr2Si3O12) is studied experimentally. Knorringite is stable at pressures above 10.5 GPa at 1200°C and 11.8 GPa at 1400°C. Below these pressures, knorringite decomposes to enstatite + eskolaite. A phase diagram of the pyrope-knorringite system is described based on the available experimental data. The solubility of the knorringite molecule in pyrope is essentially dependent only on pressure, and the Cr/Cr+Al value of garnet is considered to be an indicator of the minimum pressure of equilibration. Consideration of the genesis of Cr-rich pyrope and other peridotitic inclusions in diamonds indicates that the fractionation process should have taken place, at least at depths to ca. 240 km, to give rise to the Cr-rich complement of Cr-poor upper mantle materials such as undepleted lherzolite. The knorringite-rich peridotitic suite in diamond will be identified with this complement, which may be the material constituting the deep upper mantle. 相似文献
As a clean form of energy able to replace oil, the demand for LNG (Liquefied Natural Gas) has been increasing. LNG must be stored in a cryogenic temperature of —162°C. The storage tanks now existing throughout the world can be divided into above-ground and inground types. In the Tokyo area, there are now 22 in-ground LNG storage tanks, either in operation or under construction, which are constructed with primary consideration given to safety and earthquake-proof design because of the circumstances around the LNG terminals.
In the feasibility study of a very large-scale, in-ground LNG storage tank, comparative preliminary studies were made of various construction methods. Among them, the method using artificial ground freezing was proposed, in which it was planned to utilize the frozen soil as the means of ground water control and the temporary retaining wall. To confirm the feasibility of the design, a model tank test was conducted by freezing the actual tank yard. The yard ground, composed of sand and silt layers, was artificially frozen 10 m in diameter and 50 m in depth; in the frozen soil a shaft of 4 m in diameter was sunk to a depth 26 m below the ground level for various tests and measurements. The purpose of the test was mainly to confirm the construction method and to examine the agreement between theory and practice.
Although this construction method has not been adopted in the actual tank work, the feasibility of the method itself has been confirmed as a result of the test. In this paper, the outline and major results of the test and analysis are described. 相似文献
In situ X-ray diffraction experiments of calcium ferrite-type MgAl2O4 have been carried out using a diamond anvil cell combined with synchrotron radiation and an imaging plate X-ray detector
under hydrostatic pressures up to 9 GPa. The observed unit-cell volumes at various pressures were fitted to the Birch-Murnaghan
equation of state, yielding a bulk modulus of KT0= 241(3) GPa when K′T0=4 is assumed. This relatively large bulk modulus of calcium ferrite-type MgAl2O4 is consistent with that expected from the systematic relation between bulk modulus and molar volume for the most compounds
possessing fcc oxygen packing.
Received March 5, 1996/Revised, accepted October 15, 1996 相似文献
To estimate the influence of mercury emitted from submarine fumaroles, the horizontal and vertical distribution of mercury in sediment of Kagoshima Bay was studied. The fumaroles are located in the northern bay head area, and the sediment samples had been taken from 52 points throughout the bay with a gravity core sampler. The core samples obtained were cut at a thickness of 1–2 cm and used for measurements. The total concentration of mercury in surface sediment in the northern and central areas of the bay was 51–679 μg kg− 1 (average 199 μg kg− 1, n = 22) and 23–100 μg kg− 1 (average 55 μg kg− 1, n = 30), respectively. The highest value was obtained in the vicinity of the fumaroles. The mercury concentration in sediment near the fumaroles varied with depth, which may reflect the variation in fumarolic activity. A successive extraction method was applied to the speciation of mercury in the sediment. The results showed that sediment taken in the vicinity of submarine fumaroles contained a higher percentage of mercury bound with organic matter. 相似文献