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91.
The Double Glacier Volcano (DGV) is a small dome complex of porphyritic hornblende andesite and dacite that is part of the Cook Inlet segment of Quaternary volcanoes of the eastern Aleutian arc. Its discovery reduces the previously described large volcano gap in Cook Inlet segment to a distance similar to that between other volcanoes in the area. DGV lavas are medium-K, calcalkaline andesites and dacites with concentrations of major and minor elements similar to the other Quaternary volcanoes of the Cook Inlet segment. Available K-Ar ages indicate that DGV was active 600–900 ka. 相似文献
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Deborah S. Kelley Marvin D. Lilley John E. Lupton Eric J. Olson 《Deep Sea Research Part II: Topical Studies in Oceanography》1998,45(12):2665-2682
The rapid field response in March and April 1996 to diking-eruptive events on the Northern Gorda Ridge allowed the first detailed co-measurement of 3He, H2, and CH4 in plumes associated with a submarine eruption, and examination of the chemical transformation of these volatile species during aging of the plumes. The diking-eruptive event generated extensive event plumes with a low 3He/heat ratio of ∼0.4×10-12 cm3 STP gm-1 °C-1, while chronic plumes had 3He/heat ratios of 2.1–6.2×10-12 cm3 STP gm-1 °C-1. Hydrogen concentrations in the initial event plume (EP96A) reached a maximum value of 47 nM, 235 times that of ocean background concentration (0.2 nM). In contrast, roughly one month later H2 concentrations, although still elevated, had drastically dropped to 40 times background values. Methane concentrations in both event and chronic plume fluids were also elevated and similar to stable hydrothermal systems in unsedimented ridge environments, reaching a maximum value of 7 nM. The intense rapid interaction at very high temperatures of hydrothermal fluids with the host rock during dike intrusion or with seawater during extrusion of the basalt likely generated high, localized concentrations of H2. The data indicate, however, that maximum rates of H2 production during event plume formation could have lasted a few days at most. 相似文献
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Four years of SBUV ozone data and NOAA/NMC temperature data are analyzed for the relations between the annual total ozone behaviour in the Northern and Southern Hemispheres and the transport of ozone by planetary waves. It is found that the interhemispheric differences in the annual variation of total ozone are well explained by the interhemispheric differences in the planetary waves and the resulting ozone transports. The annual variation of the ozone transports by the stationary waves is found to control the ozone behavior in both hemispheres. Both the day-to-day and the interannual variation in total ozone are found to be strongly related to the corresponding variability of the planetary waves.Contribution Number 46 of the Stratospheric General Circulation with Chemistry Project at NASA/GSFC. 相似文献
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Marvin L. White 《Astrophysics and Space Science》1972,16(2):295-310
The rotation of a compressible inviscid fluid disc of (1) slowly varying density or (2) nonuniform density (cold gas approximation) or (3) nonuniform density (hot, but tenuous) is considered. Perturbation methods for solving the basic equation for conservation of vorticity are used. It is found that steady state conditions are realized when vortex waves and differential rotation (jet streams) coexist; special solutions for these vortex waves are obtained. For one of these solutions, a given jet stream and its associated vortex (only one vortex per jet allowed) wave can exist only at certain discrete orbital distances, given by a geometric progressionA
n
wheren is an integer andA is a constant. This progression is a good representation for the distances of planets and satellites, with small orbital inclinations, from their respective parent bodies. Certain other solutions for the vortex wave yield streamlines that are logarithmic spirals. Some justifications are given for applying the model to the dynamics of hurricanes and spiral galaxies. Comparisons with observations are surprisingly favorable.The possible role of the jet streams and the steady state long vortex waves (a cooperative-vortex phenomenon) in the formation and evolution of the solar system is also discussed. Comparisons are made with the von Weizsäcker (1944 and Chandrasekhar, 1946) model of turbulent eddies in the solar nebula and with the particle (asteroidal) jet streams of Alfvén and Arrhenius (1970a, b). 相似文献