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151.
152.
Gerhard H. Eisbacher 《Mineralium Deposita》1969,4(2):219-224
Magnesitknollen in den roten Tonschiefern des alpinen Buntsandsteins (Werfener Schiefer) wurden in fast allen der bearbeiteten Profile zwischen Innsbruck und Saalfelden angetroffen. Es handelt sich um drei Typen von Magnesitknollen, die in ihrer Genese voneinander abweichen: 1. Kryptokristalline Konkretionen frühdiagenetischer Ausfällung; 2. Syntektonische Rekristallisationsgefüge von knolligem Habitus, die in ihrer Entstehung zeitlich mit der Durchbewegung der sandig-tonigen Nebengesteine zusammenfallen; 3. Postdeformative Spatmagnesite, welche innerhalb des schiefrigen Starrgefüges als Konkretionen auskristallisierten und die Wegsamkeit der Schieferung als bevorzugte Wachstumsrichtung benützten.
Nodular magnesite has been found in most sections of Lower Triassic red beds (Werfener Schiefer) of the Northern Calcareous Alps between Innsbruck and Saalfelden, Austria. Three genetic types of magnesite can be differentiated: 1. Cryptocrystalline concretions of early diagenetic origin; 2. Syntectonic recrystallisation fabrics of nodular habit which formed while the sandshale matrix underwent deformation; 3. Post-tectonic spar-magnesite concretions which grew preferentially along tectonic cleavage surfaces.相似文献
153.
An improved value of coronal temperature is obtained by the degree of ionization method taking various processes into consideration. Comparison with some of the existing results has also been made. 相似文献
154.
J. A. Vorpahl E. G. Gibson P. B. Landecker D. L. McKenzie J. H. Underwood 《Solar physics》1975,45(1):199-216
132 soft X-ray flare events have been observed with The Aerospace Corporation/Marshall Space Flight Center S-056 X-ray telescope that was part of the ATM complement of instruments aboard Skylab. Analyses of these data are reported in this paper. The observations are summarized and a detailed discussion of the X-ray flare structures is presented. The data indicated that soft X-rays emitted by a flare come primarily from an intense well-defined core surrounded by a region of fainter, more diffuse emission. Loop structures are found to constitute a fundamental characteristic of flare cores and arcades of loops are found to play a more important role in the flare phenomena than previously thought. Size distributions of these core features are presented and a classification scheme describing the brightest flare X-ray features is proposed. The data show no correlations between the size of core features and: (1) the peak X-ray intensity, as indicated by detectors on the SOLRAD satellite; (2) the rise time of the X-ray flare event, or (3) the presence of a nonthermal X-ray component. An analysis of flare evolution indicates evidence for preliminary heating and energy release prior to the main phase of the flare. Core features are found to be remarkably stable and retain their shape throughout a flare. Most changes in the overall configuration seem to be the result of the appearance, disappearance or change in brightness of individual features, rather than the restructuring or re-orientation of these features. Brief comparisons with several theories are presented. 相似文献
155.
Viking images of Martian craters with rampart-bordered ejecta deposits reveal distinct impact ejecta morphology when compared to that associated with similar-sized craters on the Moon and Mercury. Topographic control of distribution, lobate and terraced margins, cross-cutting relationships, and multiple stratigraphic units are evidence for ejecta emplacement by surface flowage. It is suggested that target water explosively vaporized during impact alters initial ballistic trajectories of ejecta and produces surging flow emplacement. The dispersal of particulates during a series of controlled steam explosions generated by interaction of a thermite melt with water has been experimentally modeled. Preliminary results indicate that the mass ratio of water to melt and confining pressure control the degree of melt fragmentation (ejecta particle size) and the energy and mode of melt-ejecta dispersal. Study of terrestrial, lobate, volcanic ejecta produced by steam-blast explosions reveals that particle size and vapor to clast volume ratio are primary parameters characterizing the emplacement mechanism and deposit morphology. Martian crater ramparts are formed when ejecta surges lose fluidizing vapors and transported particles are deposited en masse. This deposition results from flow yield strength increasing above shear stress due to interparticle friction. 相似文献
156.
A total of 12 indices of temperature extremes and 11 indices of precipitation ex-tremes at 111 stations in southwestern China at altitudes of 285-4700 m were examined for the period 1961-2008. Significant correlations of temperature extremes and elevation in-cluded the trends of diurnal temperature range, frost days, ice days, cold night frequency and cold day frequency. Regional trends of growing season length, warm night frequency, coldest night and warmest night displayed a statistically significant positive correlation with altitude. These characteristics indicated the obvious warming with altitude. For precipitation extreme indices, only the trends of consecutive dry days, consecutive wet days, wet day precipitation and the number of heavy precipitation days had significant correlations with increasing alti-tude owing to the complex influence of atmospheric circulation. It also indicated the increased precipitation mainly at higher altitude areas, whereas the increase of extreme precipitation events mainly at lowers altitude. In addition, the clearly local influences are also crucial on climate extremes. The analysis revealed an enhanced sensitivity of climate extremes to ele-vation in southwestern China in the context of recent warming. 相似文献
157.
158.
G. R. Huguenin A. E. Lilley W. H. McDonough M. D. Papagiannis 《Planetary and Space Science》1964,12(12):1157-1167
Radio noise observations at frequencies of 0·700 Mc and 2·200 Mc were made at altitudes between 3000 and 11,000 km from a Blue Scout Jr. high-altitude rocket probe on 30 July 1963. A steady background flux of (7·5−3+6) × 10−19 W m−2)(c/s)−1 at 0·700 Mc and (1·8+1.0−0.5 × 10−19 W m−2 (c/s)−1 at 2·200 Mc was observed. Assuming a galactic origin of the observed fluxes at both frequencies, the averaged sky brightnesses are b(0·700 Mc) = (6−3+5) × 10−20 W m−2 (c/s)−1 sr−1b(2·200 Mc) = (1.4+1.0−0.5 × 10−20 W m−2 (c/s)−1 sr−1 The observed brightness at 2·200 Mc is in reasonable agreement with the results of other observers. The apparent brightness at 0·700 Mc is, however, greater than was expected from previous observations. An alternative source of the 0·700 Mc flux in the terrestrial exosphere, as well as characteristics of several noise bursts observed during the flight, is briefly discussed. 相似文献
159.
土地利用变化空间模拟的进展--CLUE-S模型及其应用 总被引:24,自引:1,他引:24
土地利用变化的空间模拟是进行土地利用情景分析的重要基础。本文在介绍了国际上常用的细胞自控模型(CA)、土地利用变化及效应模型(CLUE)的基础上,重点分析了小尺度土地利用变化及效应模型(CLUE-S)的方法,并以邯郸地区为例进行了案例研究。认为CLUE-S模型采取经验模型的方法,通过建立土地利用空间分配和驱动因子之间的统计关系模拟近期土地利用变化的情景。同时也考虑了不同土地利用方式之间的竞争关系,因此可以较好地模拟小尺度地区的近期土地利用变化情景;考虑到短期或近期土地利用变化的因子主要与人类的社会经济活动有关,而社会经济因子的空间化尚存在一定难度。因此,突破这一瓶颈成为CLUE-S模型发展和应用的关键;CLUE-S模型主要解决的是不同空间尺度上的土地利用空间分配问题,在土地生产潜力评价、土地利用规划等方面具有广阔的应用前景。 相似文献
160.
Thermal expansion during the first heating cycle at atmospheric pressure was measured in several directions in seven igneous rocks between 25° and 400°C at slow heating rates. The coefficient of thermal expansion measured under these conditions increases more rapidly as temperature is increased than the average thermal expansion coefficient of the constituent minerals. The “extra” expansion is attributed to the formation of cracks by differential expansion of mineral grains. The presence of such cracks in the rocks during the cooling part of the cycle and during any subsequent heating and cooling cycles will result in a substantial decrease in the coefficient of thermal expansion as compared to that measured during the first heating cycles. The effect of cracks initially present in a rock was studied by measuring the full tensor of the coefficient of thermal expansion on two rocks with anisotropic crack distributions. In these two rocks the coefficient of thermal expansion is least in the direction perpendicular to the plane of greatest crack concentration. The implication of our data is that thermal expansion depends greatly on the fracture state of the rock. Both the fractures in the rock and the boundary conditions on the rock are significant for the interpretation of thermal expansion measurements and for their application to other problems. 相似文献