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441.
北喀斯喀特边缘IODP 311航次断面的地震结构、天然气水合物含量和滑塌构造 总被引:1,自引:0,他引:1
北喀斯喀特活动边缘的增生楔沉积物中含有分布广泛的天然气水合物一直延伸到海底下几百米的深度。为了评估天然气水合物的长期能源潜力和它在全球气候变化及边坡稳定性中的作用,2005年9月IODP311航次建立了一个详细的地质模型来解释水合物的形成与分解以及它与穿过大陆边缘流体流的伴生关系。在考察前,先在大陆坡上进行地震试验以提供支持钻井的地球物理信息。 相似文献
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George W. Wetherill 《Astrophysics and Space Science》1996,241(1):25-34
Models of planetary formation can be tested by comparison of their ability to predict features of our Solar System in a consistent way, and then extrapolated to other hypothetical planetary systems by different choice of parameters. When this is done, it is found that the resulting systems are insensitive to direct effects of the mass of the star, but do strongly depend on the properties of the disk, principally its surface density. Major uncertainty results from lack of an adequate theoretical model that predicts the existence, size, and distribution of analogs of our Solar System, particularly the gas giants Jupiter and Saturn. Nevertheless, reasons can be found for expecting that planetary systems, including those containing biologically habitable planets similar to Earth, may be abundant in the Galaxy and Universe. 相似文献
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We review two models describing the Venus climate system: the carbonate and pyrite models. It has been argued carbonate and pyrite are potentially important minerals controlling the climate of Venus, though existence of either minerals has not been confirmed. Although it used to be proposed that carbonation reaction might explain the Venus’ atmospheric CO2 abundance, it is unlikely Venus’ surface is reactive enough to control the Venus’ massive CO2 atmosphere. Venus’ surface carbonate is also able to affect the climate through the reaction with atmospheric SO2 to form anhydrite. Under the carbonate model the climate state is not in equilibrium and would be unstable due to the reaction between carbonate and SO2. On the other hand, pyrite-magnetite reaction is proposed to explain the Venus’ atmospheric SO2 abundance. Under pyrite-magnetite reaction, however, the climate would be stabilized such that the existing climate state is maintained over a geological timescale, while some observational facts such as atmospheric abundance of SO2 and surface temperature could also be reasonably explained. 相似文献
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Vincent M. Woolf George Wallerstein 《Monthly notices of the Royal Astronomical Society》2005,356(3):963-968
We report the first survey of chemical abundances in M and K dwarf stars using atomic absorption lines in high-resolution spectra. We have measured Fe and Ti abundances in 35 M and K dwarf stars using equivalent widths measured from λ/Δλ≈ 33 000 spectra. Our analysis takes advantage of recent improvements in model atmospheres of low-temperature dwarf stars. The stars have temperatures between 3300 and 4700 K, with most cooler than 4100 K. They cover an iron abundance range of −2.44 < [Fe/H] < +0.16 . Our measurements show [Ti/Fe] decreasing with increasing [Fe/H], a trend similar to that measured for warmer stars, where abundance analysis techniques have been tested more thoroughly. This study is a step towards the observational calibration of procedures to estimate the metallicity of low-mass dwarf stars using photometric and low-resolution spectral indices. 相似文献
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William J. Chaplin Yvonne Elsworh Rachel Howe George R. Isaak Clive P. McLeod Brek A. Miller H. B. Van Der Raay Sarah J. Wheeler Roger New 《Solar physics》1996,168(1):1-18
Since 1981 we have been operating the Birmingham Solar-Oscillations Network (BiSON), a global network of resonant-scattering spectrometers, observing the low-l solar p modes. Here we discuss historical developments, culminating in the establishment of a 6-station network in 1992 September, and the subsequent performance of that network. The data record of each station from 1992 to 1994 has been analysed in terms of weather and equipment breakdowns. Our early experience suggests that the best long-term coverage possible with a 6-station network is limited in practice to about 80%, which falls short of previous predictions. 相似文献