Cathodoluminescence of high-pressure feldspar minerals as a shock barometer     

Masahiro Kayama  Toshimori Sekine  Naotaka Tomioka  Hirotsugu Nishido  Yukako Kato  Kiyotaka Ninagawa  Takamichi Kobayashi  Akira Yamaguchi 《Meteoritics & planetary science》2018,53(7):1476-1488

Cathodoluminescence (CL) analyses were carried out on maskelynite and lingunite in L6 chondrites of Tenham and Yamato-790729. Under CL microscopy, bright blue emission was observed in Na-lingunite in the shock veins. Dull blue-emitting maskelynite is adjacent to the shock veins, and aqua blue luminescent plagioclase lies farther away. CL spectroscopy of the Na-lingunite showed emission bands centered at ~330, 360–380, and ~590 nm. CL spectra of maskelynite consisted of emission bands at ~330 and ~380 nm. Only an emission band at 420 nm was recognized in crystalline plagioclase. Deconvolution of CL spectra from maskelynite successfully separated the UV–blue emission bands into Gaussian components at 3.88, 3.26, and 2.95 eV. For comparison, we prepared K-lingunite and experimentally shock-recovered feldspars at the known shock pressures of 11.1–41.2 GPa to measure CL spectra. Synthetic K-lingunite has similar UV–blue and characteristic yellow bands at ~550, ~660, ~720, ~750, and ~770 nm. The UV–blue emissions of shock-recovered feldspars and the diaplectic feldspar glasses show a good correlation between intensity and shock pressure after deconvolution. They may be assigned to pressure-induced defects in Si and Al octahedra and tetrahedra. The components at 3.88 and 3.26 eV were detectable in the lingunite, both of which may be caused by the defects in Si and Al octahedra, the same as maskelynite. CL of maskelynite and lingunite may be applicable to estimate shock pressure for feldspar-bearing meteorites, impactites, and samples returned by spacecraft mission, although we need to develop more as a reliable shock barometer.  相似文献   

BALLOON-BORNE MEASUREMENTS OF AEROSOL VERTICAL DISTRIBUTIONS OVER BEIJING DURING THE SUMMER AND AUTUMN OF 1993          下载免费PDF全文

Zhou Jun  Tan Kun  Shao Shisheng  Gong Zhiben  Shi Guangyu  Guo Jiandong  Wang Biao  Zhang Baowu  Sun Baolai  Yasunobu Iwasak  Masahiko Hayashi  Masahiro Hase 《Acta Meteorologica Sinica》1994,8(4):478-487

The results of two balloon soundings during the summer and autumn of 1993 from the Xianghe Observation Station are being utilized in a study of the temporal and spatial distribution of the atmospheric aerosols.The balloon,gondola,instrumentation and atmospheric conditions during the observation period are described.The temporal and spatial characteristics of aerosol concentration,size ratio,mixing ratio,and size distribution for both troposphere and strato-sphere are presented and analyzed.  相似文献   

Influence of surface and vegetation characteristics on C-band radar measurements for soil moisture content   总被引：1，自引：0，他引：1  

Shakil Ahmad Romshoo  Masahiro Koike  Sadayukihir Onaka  Taikan Oki  Katumi Musiake 《Journal of the Indian Society of Remote Sensing》2002,30(4):229-244

Soil moisture estimation using microwave remote sensing faces challenges of the segregation of influences mainly from roughness and vegetation. Under static surface conditions, it was found that Radarsat C-band SAR shows reasonably good correlation and sensitivity with changing soil moisture. Dynamic surface and vegetation conditions are supposed to result in a substantial reduction in radar sensitivity to soil moisture. A C-band scatterometer system (5.2 GHz) with a multi-polarization and multi-angular configuration was used 12 times to sense the soil moisture over a tall vegetated grass field. A score of vegetation and soil parameters were recorded on every occasion of the experiment. Three radar backscattering models Viz., Integral Equation Model (IEM), an empirical model and a volume scattering model, have been used to predict the backscattering phenomena. The volume scattering model, using the Distorted Born Approximation, is found to predict the backscattering phenomena reasonably well. But the surface scattering models are expectedly found to be inadequate for the purpose. The temporal variation of soil moisture does show good empirical relationship with the observed radar backscattering. But as the vegetation biomass increases, the radar shows higher sensitivity to the vegetation parameters compared to surface characteristics. A sensitivity analysis of the volume scattering model for all the parameters also reveals that the radar is more sensitive to plant parameters under high biomass conditions, particularly vegetation water content, but the sensitivity to surface characteristics, particularly to soil moisture, is also appreciable.  相似文献   

Thermal diffusivity of lunar rocks under atmospheric and vacuum conditions     

Naoyuki Fujii  Masahiro Osako 《Earth and Planetary Science Letters》1973,18(1):65-71

Thermal diffusivity, k, of three lunar rocks (10049 and 10069; Type A, Apollo 11 and 14311; Apollo 14) and a terrestrial basalt (alkaline olivine basalt, Oki-do?go, Japan) was measured under one atmosphere and in vacuum conditions (10^?3 ～ 10^?5 mmHg) in the temperature range from 85 to 850°K. The semi-empirical curve of k =A + B/T +CT³ is fitted to the data in each condition. The porosity of rocks strongly affects the thermal diffusivity at low temperature ( T ? 500°K) in vacuum condition. At 150°K, thermal diffusivity of lunar rocks with porosity of 5.5% (10049) and 11% (10069) at one atmosphere is about 1.7 and 3.2 times of that in vacuum, respectively. The difference between the values at one atmosphere and those in vacuum decreases as the temperature increases. Measurements of k should be made at gas pressures at least lower than 10^?3 mmHg to estimate the value under lunar surface conditions.  相似文献   

On-going orogeny in the outer-arc of the Timor–Tanimbar region, eastern Indonesia     

Yoshiyuki Kaneko  Shigenori Maruyama  Ade Kadarusman  Tsutomu Ota  Masahiro Ishikawa  Tatsuki Tsujimori  Akira Ishikawa  Kazuaki Okamoto   《Gondwana Research》2007,11(1-2):218

The Timor–Tanimbar islands of eastern Indonesia form a non-volcanic arc in front of a 7 km deep fore-arc basin that separates it from a volcanic inner arc. The Timor–Tanimbar Islands expose one of the youngest high P/T metamorphic belts in the world, providing us with an excellent opportunity to study the inception of orogenic processes, undisturbed by later tectonic events.Structural and petrological studies of the high P/T metamorphic belt show that both deformation and metamorphic grade increase towards the centre of the 1 km thick crystalline belt. Kinematic indicators exhibit top-to-the-north sense of shear along the subhorizontal upper boundaries and top-to-the-south sense in the bottom boundaries of the high P/T metamorphic belt. Overall configuration suggests that the high P/T metamorphic rocks extruded as a thin sheet into a space between overlying ophiolites and underlying continental shelf sediments. Petrological study further illustrates that the central crystalline unit underwent a Barrovian-type overprint of the original high P/T metamorphic assemblages during wedge extrusion, and the metamorphic grade ranged from pumpellyite-actinolite to upper amphibolite facies.Quaternary uplift, marked by elevation of recent reefs, was estimated to be about 1260 m in Timor in the west and decreases toward Tanimbar in the east. In contrast, radiometric ages for the high P/T metamorphic rocks suggest that the exhumation of the high P/T metamorphic belt started in western Timor in Late Miocene time and migrated toward the east. Thus, the tectonic evolution of this region is diachronous and youngs to the east. We conclude that the deep-seated high P/T metamorphic belt extrudes into shallow crustal levels as a first step, followed by doming at a later stage. The so-called ‘mountain building’ process is restricted to the second stage. We attribute this Quaternary rapid uplift to rebound of the subducting Australian continental crust beneath Timor after it achieved positive buoyancy, due to break-off of the oceanic slab fringing the continental crust. In contrast, Tanimbar in the east has not yet been affected by later doming. A wide spectrum of processes, starting from extrusion of the high P/T metamorphic rocks and ending with the later doming due to slab break-off, can be observed in the Timor–Tanimbar region.  相似文献   

Preparation of Two New GSJ Geochemical Reference Materials: Basalt JB-1b and Coal Fly Ash JCFA-1   总被引：1，自引：0，他引：1  

Shigeru Terashima  Masahiro Taniguchi  Masumi Mikoshiba  Noboru Imai 《Geostandards and Geoanalytical Research》1998,22(1):113-117

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Relations between load and settlement of circular foundations on or in a dense sand expressed by a function of diameter and depth     

Hiroaki Nagaoka  Masahiro Yamazaki  Naoto Kubota  Takashi Okamoto 《国际地质力学数值与分析法杂志》2005,29(6):551-576

When load acts on a circular foundation on or in a dense sand, average contact pressure on the lower surface of the foundation is q and settlement of the foundation is s. Diameter and depth of the foundation are B and D_f. When the sand, B and D_f are given, we can know the relation between q and s/B by, e.g. a loading test, i.e. the relation is determined by B and D_f for the sand. Using the results of numerical analyses, we express a relation between q and s/B up to s=0.1B by functions of a single variable which is a linear combination of B and D_f. Consequently when two foundations have different B's and different D_f's but have the same value of the variable, the relations are the same. Then we examine whether the functions can express the results of eleven tests of model foundations of wide range of B and/or D_f. In all the tests, the relations are expressed with sufficient accuracy. Copyright © 2005 John Wiley & Sons, Ltd.  相似文献   

Response of a simple two-layer ocean to divergent and rotational wind stress     

Masahiro Endoh 《Journal of Oceanography》1971,27(3):116-120

Response of an unbounded two-layer ocean to traveling atmospheric disturbances is analytically investigated. Under the assumption that (1) lower layer is motionless, (2) each layer is homogeneous and in hydrostatic balance, (3) the Coriolis parameter is constant, and (4) the density difference between the two layers is small compared to the density itself, the one-dimensional Klein-Gordon's equation is solved analytically for both the divergent and rotational wind stress. Numerical examples of the wake pattern of the upwelling behind the regional divergent and rotational wind fields are also represented.The results may be summarized as follows: (1) the effect of the divergent wind stress is dominant when the forced Rossby numberR ₀ (the ratio of the frequency of the wind stress to the Coriolis parameter) is larger than unity unless the Mach numberM (the ratio of the traveling velocity of the wind stress to the internal gravitational velocity) is far less than unity, (2) the effect of the rotational wind stress is important, when the forced Rossby numberR ₀ is less than unity.  相似文献   

Comparison of the acid-base responses to CO2 and acidification in Japanese flounder (Paralichthys olivaceus)     

Hayashi M  Kita J  Ishimatsu A 《Marine pollution bulletin》2004,49(11-12):1062-1065

To investigate whether the biological toxicity of aquatic hypercapnia is due to the direct effects of CO2 or to the effects of acidification of seawater by CO2, the Japanese flounder (Paralichthys olivaceus) was subjected to seawater equilibrated with a gas mixture of air containing 5% CO2 (pH 6.18) or seawater acidified to the same pH with 1 N H2SO4. All the fish died within 72 h in the CO2 exposure group, whereas no mortality occurred in the acid group. Acid-base parameters as well as plasma ion concentrations were severely perturbed in the CO2 exposure group, whereas they were minimally affected in the acid group. These results clearly demonstrate that the mortality in the CO2 group is a direct result of the elevated levels of dissolved CO2 and not to the effects of the reduced water pH.  相似文献   

Perturbed physics ensemble using the MIROC5 coupled atmosphere–ocean GCM without flux corrections: experimental design and results     

Hideo Shiogama  Masahiro Watanabe  Masakazu Yoshimori  Tokuta Yokohata  Tomoo Ogura  James D. Annan  Julia C. Hargreaves  Manabu Abe  Youichi Kamae  Ryouta O’ishi  Rei Nobui  Seita Emori  Toru Nozawa  Ayako Abe-Ouchi  Masahide Kimoto 《Climate Dynamics》2012,39(12):3041-3056

In this study, we constructed a perturbed physics ensemble (PPE) for the MIROC5 coupled atmosphere–ocean general circulation model (CGCM) to investigate the parametric uncertainty of climate sensitivity (CS). Previous studies of PPEs have mainly used the atmosphere-slab ocean models. A few PPE studies using a CGCM applied flux corrections, because perturbations in parameters can lead to large radiation imbalances at the top of the atmosphere and climate drifts. We developed a method to prevent climate drifts in PPE experiments using the MIROC5 CGCM without flux corrections. We simultaneously swept 10 parameters in atmosphere and surface schemes. The range of CS (estimated from our 35 ensemble members) was not wide (2.2–3.2?°C). The shortwave cloud feedback related to changes in middle-level cloud albedo dominated the variations in the total feedback. We found three performance metrics for the present climate simulations of middle-level cloud albedo, precipitation, and ENSO amplitude that systematically relate to the variations in shortwave cloud feedback in this PPE.  相似文献