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排序方式: 共有347条查询结果,搜索用时 15 毫秒
1.
In situ strength measurements on natural upper-mantle minerals 总被引:1,自引:0,他引:1
Junji Yamamoto Jun-ichi Ando Hiroyuki Kagi Toru Inoue Akihiro Yamada Daisuke Yamazaki Tetsuo Irifune 《Physics and Chemistry of Minerals》2008,35(5):249-257
Using in situ strength measurements at pressures up to 10 GPa and at room temperature, 400, 600, and 700°C, we examined rheological
properties of olivine, orthopyroxene, and chromian-spinel contained in a mantle-derived xenolith. Mineral strengths were estimated
using widths of X-ray diffraction peaks as a function of pressure, temperature, and time. Differential stresses of all minerals
increase with increasing pressure, but they decrease with increasing temperature because of elastic strain on compression
and stress relaxation during heating. During compression at room temperature, all minerals deform plastically at differential
stress of 4–6 GPa. During subsequent heating, thermally induced yielding is observed in olivine at 600°C. Neither orthopyroxene
nor spinel shows complete stress relaxation, but both retain some stress even at 700°C. The strength of the minerals decreases
in the order of chromian-spinel ≈ orthopyroxene > olivine for these conditions. This order of strength is consistent with
the residual pressure of fluid inclusions in mantle xenoliths. 相似文献
2.
The instability of oscillatory flows in a two-layer fluid where the two layers differ in density and viscosity has been analysed using a perturbation method for long waves with special interest on effects of viscosity, time scale, density and depth of the fluid. The flow of a fluid with homogeneous density can be unstable, when the kinematic viscosity of the upper fluid layer is different from that of the lower one. Viscosity stratification results in unstable oscillatory flows. Two limiting cases of single-layer flow are also considered. 相似文献
3.
Comparison experiment between XBT of T-7 probe and CTD was conducted at 15 stations in the sea area centered on 29°N, 135°E in December 1985. There were systematic errors in XBT temperature profiles in comparison with CTD temperature profiles. The main cause of errors was attributed to an error in the free-fall speed of the XBT probes which was provided by the XBT maker. A previous equation for depth correction proposed by Heinmilleret al. (1983) could not give effective correction for our data. A new equation between the probe depth and the elapsed time from landing of the probe on the water was obtained by the method of adjusting temperature gradients of XBT profiles to those of CTD profiles. This equation agreed with the theoretical result given by Seaver and Kuleshov (1982) much better than that of Heinmilleret al. (1983). Systematic errors due to a scatter of values of the reference resistance and variation of B-constant of thermistors used in XBT also seemed to exist. After an adjustment using the temperature difference between XBT and CTD in the mixed layer with depths of about 100 m, the standard deviation of temperature difference between XBT and CTD from the surface to the depth of 750 m was 0.14°C. 相似文献
4.
The S/V Shoyo, of the Hydrographic Department, Japan Coast Guard, has conducted high-density expendable bathythermograph (XBT)
measurements along the 32.5°N line in the North Pacific every year from 1990 to 1993 as a part of the Japanese-World Ocean
Circulation Experiment (WOCE). These XBT data are analyzed here, focusing on year-to-year variations of the inventory and
core layer temperature (CLT) of the North Pacific subtropical mode water (NPSTMW). Large year-to-year changes are found in
the NPSTMW CLTs estimated in longitudes between 140°E and 160°E. CLT values were found of 17.4°C in 1990, 17.1°C in 1991,
17.3°C in 1992 and 17.6°C in 1993. Inspection of the wintertime westerlies over the formation area and sea surface temperature
distribution revealed that this change in CLT can be qualitatively attributed to the strength of atmospheric cooling in the
formation area in the previous winter. Although a large year-to-year variation of NPSTMW inventory was also found, it is hard
to state any relationship between CLT and atmospheric forcing. There is a possibility that different observational seasons
may affect the inventory. It has also been found that the thermocline depth in 1991 was shallower in the sea area east of
180° than in 1992 and 1993. Associated with this change, the North Pacific central mode water (NPCMW), characterized by thermostad
with temperatures ranging from 14°C to 11°C, appears in the sea area east of 180° in the 1992 and 1993 cross sections. The
1993 cross section, which ranged from the Japanese coast to the west coast of North America, possessed another thermostad
in the surface layer, with a temperature of about 17°C in the eastern part of the cross section, off California.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
5.
The accuracy of the manufacturer’s fall-rate equation for the T-5 Model of expendable bathythermograph (XBT) has been investigated based on about 300 collocated pairs of XBT-CTD (Conductivity-Temperature-Depth profiler) measurements in various climatological regions. We found that the equation systematically overestimates depth by about 5% for the T-5 produced by Tsurumi Seiki, Co. Ltd. (TSK), but almost no bias is associated with the T-5 produced by Sippican, Inc., in USA. The cause of this difference is not clear, because the two manufacturers’ T-5 probes are reported to have identical shape and weight in water. We propose a new fall-rate equation for the TSK T-5: z(t) = 6.54071t - 0.0018691t
2, where z(t) is depth in meters at time, t, in seconds. 相似文献
6.
Takushi?NikiEmail author Taiki?Fujinaga Mariyo?F.?Watanabe Junji?Kinoshita 《Journal of Oceanography》2004,60(5):913-917
Solid-phase microextraction (SPME) is a simple, sensitive and less destructive method for the determination of dimethylsulfide
(DMS) in seawater. Combined with detection by gas chromatography-mass spectrometry (GC-MS), the method had sufficient sensitivity
(minimum detectable concentration of DMS was 0.05 nM), and practical levels of reproducibility (relative standard deviation
≤7%) and linearity (r
2 > 0.995) over a wide concentration range (0.5 to 910 nM). The protocol developed was applied to a Sagami Bay water sample
to determine concentrations of DMS and DMSP, and in situ DMSP-lyase activity. 相似文献
7.
Detecting fluctuations of the Kuroshio axis south of Japan using TOPEX/POSEIDON altimeter data 总被引:1,自引:0,他引:1
Shiro Imawaki Mayumi Gotoh Hiroyuki Yoritaka Noriya Yoshioka Atsunobu Misumi 《Journal of Oceanography》1996,52(1):69-92
Sea surface dynamic topography (SSDT) can be divided into temporal mean SSDT and fluctuation SSDT. The former is approximated with a climatological mean SSDT and the latter is derived from satellite altimetry data, to give an approximated total SSDT (called a composite SSDT). The method is applied to detecting fluctuations of the Kuroshio axis south of Japan using TOPEX/POSEIDON altimeter data from the first year mission in 1992–1993. The fluctuation SSDT averaged over a wide area south of Japan clearly shows an annual cycle with an amplitude of about 15 cm. Temporal changes of SSDT along a subsatellite track crossing the Kuroshio compare moderately well with those estimated from repeated hydrographic observations, although there is a discrepancy of unknown origin. The composite SSDT also compares well with SSDT estimated from the same hydrographic data. Horizontal distribution of the surface geostrophic velocity component normal to subsatellite tracks is derived every ten days from the composite SSDT. Most locations of estimated strong eastward geostrophic velocities coincide well with locations of the Kuroshio axis determined every 15 days fromin situ surface velocity measurements on various vessels; for example, a fairly large meander of the Kuroshio south of Honshu is clearly detected. It is concluded that the composite SSDT can be used reliably to detect fluctuations of the Kuroshio axis south of Japan. 相似文献
8.
Toshimichi Ito Arata Kaneko Hiroyuki Tsubota Noriaki Gohda 《Journal of Oceanography》1994,50(4):465-477
The localized near-bottom water with silica content higher than that in the adjacent shelf water was observed to exist at the eastern margins of the East China Sea continental shelf. The core of the high silica water possessed the silica content corresponding to that in the Kuroshio at depths greater than on the shelf. The mixing analysis of water masses using temperature (T) and silica (Si) showed that the core water can be produced through the vertical mixing of intermediate water of the Kuroshio deeper than 100 m. This study provides us a conclusion that the intermediate water of the Kuroshio is strongly mixed on the shelf slope and then upwelled to form the ridge-like distribution of water masses with low temperature and high silica content at the shelf edge. 相似文献
9.
Arata Kaneko Hiroyuki Honji Kazuo Kawatate Shinjiro Mizuno Akira Masuda Tsunehiro Miita 《Journal of Oceanography》1986,42(1):75-82
An internal wavetrain, generated by a tidal current in superposition with the Tsushima Warm Current, has been observed by use of an acoustic echo-sounder upstream of the Shichiri-Ga-Sone Seamounts in the East Tsushima Strait of the Japan Sea. The sea surface above the internal wavetrain was simultaneously observed and was found to be undulated at the wavelength of the internal wave. 相似文献
10.
Makoto Yamano Masataka Kinoshita Shusaku Goto 《International Journal of Earth Sciences》2008,97(2):345-352
Thirty-three new measurements on the seaward slope and outer rise of the Japan Trench along a parallel of 38°45′N revealed
the existence of high heat flow anomalies on the subducting Pacific plate, where the seafloor age is about 135 m.y.. The most
prominent anomaly with the highest value of 114 mW/m2 is associated with a small mound on the outer rise, which was reported to be a kind of mud volcano. On the seaward slope
of the trench, heat flow is variable: high (70–90 mW/m2) at some locations and normal for the seafloor age (about 50 mW/m2) at others. The spatial variation of heat flow may be related to development of normal faults and horst/graben structures
due to bending of the Pacific plate before subduction, with fluid flow along the fault zones enhancing the vertical heat transfer.
Possible heat sources of the high heat flow anomalies are intra-plate volcanism in the last several million years like that
discovered recently on the Pacific plate east of the Japan Trench. 相似文献