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81.
Lars Wåhlin 《Astrophysics and Space Science》1981,76(1):259-260
In a closed gravitationally-bound Universe we are subject to an inward accelerationa
0. One consequence of this acceleration is that matter will radiate and create a black-body spectrum throughout the Universe. Using the valuea
0=7.623×10–12 ms–2 and a radiation formula from a previously-described cosmological model (Wåhlin, 1981), we obtain a black-body temperature of 2.766 K. 相似文献
82.
At the Swedish Solar Observatory in Anacapri we have simultaneously used the following combination of instruments in our investigation of active regions:
- A spectrograph with an image rotator placed in front of the slit.
- A subtractive double dispersive spectrograph (solar Chromatograph).
- A Hα+0.5 Å patrol instrument. Scans over the 3b flare of August 4th 1972 are used to illustrate the method. The illustrations clearly show downflowing matter connected with bright knots and filaments in the emitting area, possibly in accordance with Hyder's infall-impact mechanism.
83.
Jo Moore Andreas Beinlich Jennifer K. Porter Cristina Talavera Jasper Berndt Sandra Piazolo Håkon Austrheim Andrew Putnis 《Journal of Metamorphic Geology》2020,38(1):103-127
As a common constituent of metamorphic assemblages, rutile provides constraints on the timing and conditions of rock transformation at high resolution. However, very little is known about the links between trace element mobility and rutile microstructures that result from synmetamorphic deformation. To address this issue, here we combine in situ LA-ICP-MS and sensitive high-resolution ion microprobe trace element data with electron back-scatter diffraction microstructural analyses to investigate the links between rutile lattice distortions and Zr and U–Pb systematics. Furthermore, we apply this integrated approach to constrain further the temperature and timing of amphibolite facies metamorphism and deformation in the Bergen Arcs of southwestern Norway. In outcrop, the formation of porphyroblastic rutile in dynamically hydrated leucocratic domains of otherwise rutile-poor statically hydrated amphibolite provides key contextual information on both the ambient conditions of hydration and deformation and the composition of the reactive fluid. Rutile in amphibolite recorded ambient metamorphic temperatures of ~590–730°C during static hydration of the granulitic precursor. By contrast, rutile from leucocratic domains in the directly adjacent shear zone indicates that deformation was accompanied by a localized increase in temperature. These higher temperatures are recorded in strain-free rutile (~600–860°C) and by Zr concentration measurements on low-angle boundaries and shear bands (620–820°C). In addition, we also observe slight depletions of Zr and U along rutile low-angle boundaries relative to strain-free areas in deformed grains from the shear zone. This indicates that crystal–plastic deformation facilitated the compositional re-equilibration of rutile upon cooling to slightly below the peak temperature of deformation. Cessation of deformation at mid-crustal conditions near ~600°C is recorded by late stage growth of small (<150 µm) rutile in the high-strain zones. U–Pb age data obtained from the strain-free and distorted rutile grains cluster in distinct populations of 437.4 ± 2.7 Ma and c. 405–410 Ma, respectively. These different ages are interpreted to reflect the difference in closure for thermally induced Pb diffusion between undeformed and deformed rutile during post-deformation exhumation and cooling. Thus, our results provide a reconstruction of the thermochronological history of the amphibolite facies rocks of the Lindås Nappe and highlight the importance of integration of microstructural data during application of thermometers and geochronometers. 相似文献
84.
Direct 40Ar/39Ar dating of Late Ordovician and Silurian brittle faulting in the southwestern Norwegian Caledonides 下载免费PDF全文
Thomas Scheiber Giulio Viola Camilla Maya Wilkinson Morgan Ganerød Øyvind Skår Deta Gasser 《地学学报》2016,28(5):374-382
Structural data as well as U–Pb zircon and 40Ar/39Ar biotite and muscovite ages were collected from the Rolvsnes granodiorite in western Norway. The granodiorite intruded at c. 466 Ma, cooled quickly and escaped later viscous deformation. Brittle top‐to‐the‐NNW thrust faults (Set I) and WNW–ESE striking dextral strike‐slip faults (Set II) formed in a NNW–SSE transpressional regime. 40Ar/39Ar dating of synkinematic mica from both sets reveals a c. 450 Ma (Late Ordovician) age of faulting, which constrains early‐Caledonian brittle deformation. Set I and II faults are overprinted by a set of lower‐grade, variably oriented chlorite‐ and epidote‐coated faults (Set III) constraining WNW–ESE shortening. A lamprophyric dyke oriented compatibly with this stress field intruded at c. 435 Ma (Silurian), indicating that Set III formed at the onset of the Scandian Baltica–Laurentia collision. The preservation of Caledonian brittle structures indicates that the Rolvsnes granodiorite occupied a high tectonic level throughout the Caledonian orogeny. 相似文献
85.
86.
Contributions of individual countries?? emissions to climate change and their uncertainty 总被引:1,自引:0,他引:1
Niklas H?hne Helcio Blum Jan Fuglestvedt Ragnhild Bieltvedt Skeie Atsushi Kurosawa Guoquan Hu Jason Lowe Laila Gohar Ben Matthews Ana Claudia Nioac de Salles Christian Ellermann 《Climatic change》2011,106(3):359-391
We have compiled historical greenhouse gas emissions and their uncertainties on country and sector level and assessed their contribution to cumulative emissions and to global average temperature increase in the past and for a the future emission scenario. We find that uncertainty in historical contribution estimates differs between countries due to different shares of greenhouse gases and time development of emissions. Although historical emissions in the distant past are very uncertain, their influence on countries?? or sectors?? contributions to temperature increase is relatively small in most cases, because these results are dominated by recent (high) emissions. For relative contributions to cumulative emissions and temperature rise, the uncertainty introduced by unknown historical emissions is larger than the uncertainty introduced by the use of different climate models. The choice of different parameters in the calculation of relative contributions is most relevant for countries that are different from the world average in greenhouse gas mix and timing of emissions. The choice of the indicator (cumulative GWP weighted emissions or temperature increase) is very important for a few countries (altering contributions up to a factor of 2) and could be considered small for most countries (in the order of 10%). The choice of the year, from which to start accounting for emissions (e.g. 1750 or 1990), is important for many countries, up to a factor of 2.2 and on average of around 1.3. Including or excluding land-use change and forestry or non-CO2 gases changes relative contributions dramatically for a third of the countries (by a factor of 5 to a factor of 90). Industrialised countries started to increase CO2 emissions from energy use much earlier. Developing countries?? emissions from land-use change and forestry as well as of CH4 and N2O were substantial before their emissions from energy use. 相似文献
87.
Sea‐bed diffractions are frequently observed for several of the fields in the Norwegian Sea and the Barents Sea. This is a challenge in time lapse seismic analysis, since diffracted multiples are difficult to remove by processing and therefore is a major source of poor time lapse data quality. In this work we test if the diffractions can be used for enhanced 4D interpretation. By analysing the time‐shift of the sea‐bed diffraction hyperbola between the base and monitor it is tested if changes in water velocity and tides can be estimated. Two models using time lapse diffraction analysis are tested: the first one simply adds time‐shifts for the two branches of the diffraction hyperbola and this average time‐shift is then used to estimate the water velocity change. The other method uses an inversion method based on the diffraction equation for a point diffractor to estimate the velocity change. In‐line common‐midpoint shifts are estimated by subtracting the time‐shifts of both hyperbola branches followed by direct inversion. The diffraction based time‐shifts are compared to time‐shifts estimated by standard cross‐correlation of the sea‐bed reflection. The averaging method gives slightly higher uncertainties, while the inversion using an exact traveltime equation gives similar uncertainties compared to the sea‐bed reflection method. 相似文献
88.
A large-scale field experiment took place in the marginal ice zone in the Barents Sea in May 2009. Fresh oil (7000 L) was released uncontained between the ice floes to study oil weathering and spreading in ice and surface water. A detailed monitoring of oil-in-water and ice interactions was performed throughout the six-day experiment. In addition, meteorological and oceanographic data were recorded for monitoring of the wind speed and direction, air temperature, currents and ice floe movements. The monitoring showed low concentrations of dissolved hydrocarbons and the predicted acute toxicity indicated that the acute toxicity was low. The ice field drifted nearly 80 km during the experimental period, and although the oil drifted with the ice, it remained contained between the ice floes. 相似文献
89.
The isostatic land uplift after the latest glaciation period in northern Europe means that the descending wave base in the
eutrophicated Baltic Sea continuously exposes new bottom areas to increasing wind and wave-induced erosion. Erosion adds considerable
amounts of phosphorus (P) and clay particles to the water column. This study has used a dynamic mass-balance model to investigate
how land uplift affects the whole P cycle in the five major subbasins of the Baltic Sea. The model uses a unitary set of variables
and constants for all subbasins with the exception of measurable, basin-specific driving variables. Differences in P concentrations
between the subbasins could be quite accurately quantified only when the land uplift gradient was used as a driving variable.
The clarifying effect from clay particles was found to be a major reason why those subbasins with the most intensive land
uplift rates were also the ones with the lowest P concentrations. Without using the land uplift gradient as a model input,
concentration differences could not be quantitatively explained in a meaningful way. Furthermore, simulations showed that
clay particle erosion from land uplift has a substantial impact on all major internal P fluxes of the Baltic Sea. At the turn
of the millennium, one of the subbasins (the Bothnian Bay) was oligotrophic, whilst the other four major subbasins were mesotrophic.
Without the clarifying effect from the clay particles added to the water column during erosion of the rising seafloor, all
five major subbasins of the Baltic Sea would probably be substantially more eutrophic. 相似文献
90.
Summary In this review we discuss recent work and progress in the modelling of photospheres of stars of spectral types F and later. Special emphasis is laid on advances as regards the consideration of atomic and molecular blanketing, non-LTE and convection and other dynamic processes. In a special chapter we discuss the possibilities of semi-empirical modelling of late-type photospheres. In the conclusions we find that much important work remains in this field, but that a considerable part of this work may in fact be carried out in a near future. 相似文献