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931.
932.
Kinetics of the air bubbles exhalation process, which occurs in overcooled cloud drops when they hit the hail or graupel particles surface. Analytical relationship between a number of bubbles generated in a drop and their size depending on the degree of overcooling of cloud drops is revealed. It is shown that the air bubbles exhalation, which accompanies the coagulation growth of hail particles, occurs on the principle of “ebullition” of the liquid on the surface of a hail particle. 相似文献
933.
934.
The Kocaçay Basin (KÇB) is a key area in western Anatolia – a well‐known extended terrane where regional segmentation has received limited attention – for investigating strike‐slip faults kinematically linked to detachment faults. In this paper, we present results of an integrated sedimentologic, stratigraphic, and structural study of Miocene alluvial fan/fan‐delta/lacustrine deposits that accumulated in the KÇB, a NE‐trending basin with connections to the Menderes Metamorphic Core Complex (MCC). We mapped and evaluated most of the key faults in the KÇB, many for the first time, and recognised different deformation events in the study area near the E margin of the MCC. We also present field evidence for kinematic connections between low‐angle normal and strike‐slip faults which were developed in an intermittently active basement‐involved transfer zone in western Anatolia. We find that the KÇB contains a detailed record of Miocene transtensional sedimentation and volcanism that accompanied exhumation of the MCC. Structural data reveal that the basin was initially formed by transtension (D1 phase) and subsequently uplifted and deformed, probably as a result of early Pliocene wrench‐ to extension‐dominated deformation (D2 phase) overprinted by Plio‐Quaternary extensional tectonics (D3 phase). These results are consistent with progressive deformation wherein the axis of maximum extension remained in the horizontal plane but the intermediate and maximum shortening axes switched position in the vertical plane. Combining our results with published studies, we propose a new working hypothesis that the KÇB was a transtensional supradetachment basin during the Miocene. The hypothesis could provide new insights into intermittently active extension‐parallel zone of weakness in western Anatolia.These results also suggest that the termination of low‐angle normal fault systems within an extension parallel transfer zone may have resulted in a transtensional depressions which are different from classical supradetachment basins with respect to the sedimentation and deformational pattern of the basin infills. 相似文献
935.
936.
937.
H.-M. Füssel 《Climatic change》2009,95(1-2):47-51
de Bruin et al. (Clim Change, 2009) report on an expert assessment aimed at prioritizing adaptation options in several climate-sensitive sectors of the Netherlands. Their results show that even in a country with high economic, institutional and technical capacity, it is not currently feasible to prioritize national-level adaptation options based on social cost-benefit analysis because of methodological difficulties and insufficient quantitative data. Multi-criteria analysis based on qualitative indicators can help prioritizing adaptation options but the analysis detected strong conflicts between priority and feasibility criteria. The specific results of the ranking exercise should be treated with caution due to weaknesses in the selection of adaptation options and the definition of evaluation criteria. The authors assert that their methods can be transferred to other regions but substantial modifications are likely required in developing countries with large current climate risks, fewer economic resources, and substantial social inequalities. 相似文献
938.
A redox profile of the Slave mantle and oxygen fugacity control in the cratonic mantle 总被引:4,自引:2,他引:4
The authors report a redox profile based on Mössbauer data of spinel and garnet to a depth of 210 km from mantle xenoliths of the northern (N) and southeastern (SE) Slave craton (northern Canada). The profile transects three depth facies of peridotites that form segments of different bulk composition, represented by spinel peridotite, spinel–garnet peridotite, low-temperature garnet peridotite, high-temperature garnet peridotite, and pyroxenite. The shallow, more depleted N Slave spinel peridotite records lower oxygen fugacities compared to the deeper, less depleted N Slave spinel–garnet peridotite, consistent with their different spinel Fe3+ concentrations. Garnet peridotites show a general reduction in log fO2 (FMQ)s with depth, where values for garnet peridotites are lower than those for spinel–garnet peridotites. There is a strong correlation between depletion and oxygen fugacity in the spinel peridotite facies, but little correlation in the garnet peridotite facies. The strong decrease in log fO2 (FMQ) with depth that arises from the smaller partial molar volume of Fe3+ in garnet, and the observation of distinct slopes of log fO2 (FMQ) with depth for spinel peridotite compared to spinel–garnet peridotite strongly suggest that oxygen fugacity in the cratonic peridotitic mantle is intrinsically controlled by iron equilibria involving garnet and spinel.
相似文献
C. McCammonEmail: Phone: +49-921-553709Fax: +49-921-553769 |
939.
David M. Harris Alfred T. Anderson Jr. 《Contributions to Mineralogy and Petrology》1984,87(2):120-128
The products of the 1974 eruption of Fuego, a subduction zone volcano in Guatemala, have been investigated through study of
silicate melt inclusions in olivine. The melt inclusions sampled liquids in regions where olivine, plagioclase, magnetite,
and augite were precipitating. Comparisons of the erupted ash, groundmass, and melt inclusion compositions suggest that the
inclusions represent samples of liquids present in a thermal boundary layer of the magma body. The concentrations of H2O and CO2 in glass inclusions were determined by a vacuum fusion manometric technique using individual olivine crystals (Fo77 to Fo71)
with glass inclusion compositions that ranged from high-alumina basalt to basaltic andesite. Water, Cl, and K2O concentrations increased by a factor of two as the olivine crystals became more iron-rich (Fo77 to Fo71) and as the glass
inclusions increased in SiO2 from 51 to 54 wt.% SiO2. The concentration of H2O in the melt increased from 1.6 wt.% in the least differentiated liquid to about 3.5% in a more differentiated liquid. Carbon
dioxide is about an order of magnitude less abundant than H2O in these inclusions. The gas saturation pressures for pure H2O in equilibrium with the melt inclusions, which were calculated from the glass inclusion compositions using the solubility
model of Burnham (1979), are given approximately by P(H2O)(Pa)=(SiO2−48.5 wt.%) × 1.45 × 107. The concentrations of water in the melt and the gas saturation pressures increased from about 1.5% to 3.5% and from 300
to 850 bars, respectively, during pre-eruption crystallization. 相似文献
940.
From the analysis of facies- and thickness distribution, and from the mapping of current directions in the flysch of the Polish Carpathian Mountains the following conclusions can be made.Source areas of detrital deposits were situated at first near the borders of the geosyncline, but at later stages a more important role was played by intrageosynclinal sources. The position of the marginal and intrageosynclinal sources was shifted during the sedimentary history of the basin from the west toward the east. Concurrently with the shift of the source areas also zones of maximal thickness were shifted. The detrital material was supplied in several sedimentary megarhythms, each beginning with coarse deposits and terminating with fine-grained sediments. This suggests intermittent sudden uplifts of source areas.The appearance and migration of the source areas is tentatively explained as not due to compressional stress but to the movements of the subcrustal material provoked by subsidence and isostatic readjustment.
Zusammenfassung Aus der Analyse von Faziesanordnung, Mächtigkeitsverteilung und Strömungsrichtungen im Flysch der polnischen Karpaten kann man folgende Schlüsse ziehen.Die Herkunftsgebiete der klastischen Sedimente lagen zunächst nahe den Rändern der Geosynkline. Später aber spielten intrageosynklinale Liefergebiete eine bedeutendere Rolle. Die Lage der randlichen und der intrageosynklinalen Liefergebiete verschob sich während der Ablagerungsgeschichte des Beckens von Westen nach Osten. Gleichlaufend wanderten die Gebiete größter Sedimentmächtigkeit. Das Abtragungsmaterial wurde in mehreren Sedimentations-Megarhythmen angeliefert, wovon jeder mit grobkörnigen Sedimenten beginnt und mit feinkörnigen endet. Das deutet intermittierende rasche Hebungen der Liefergebiete an.Es wird versucht, das Hervortreten und die Wanderung der Liefergebiete nicht durch Einengungstektonik zu erklären, sondern durch subkrustale Massenbewegungen, die durch Trogsenkung und isostatischen Ausgleich hervorgerufen wurden.相似文献