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41.
Andr�� Steenken M��nica G. L��pez de Luchi Carmen Mart��nez Dopico Malte Drobe Klaus Wemmer Siegfried Siegesmund 《International Journal of Earth Sciences》2011,100(2-3):465-488
The Eastern Sierras Pampeanas were structured by three main events: the Ediacaran to early Cambrian (580?C510?Ma) Pampean, the late Cambrian?COrdovician (500?C440?Ma) Famatinian and the Devonian-Carboniferous (400?C350?Ma) Achalian orogenies. Geochronological and Sm?CNd isotopic evidence combined with petrological and structural features allow to speculate for a major rift event (Ediacaran) dividing into two Mesoproterozoic major crustal blocks (source of the Grenvillian age peaks in the metaclastic rocks).This event would be coeval with the development of arc magmatism along the eastern margin of the eastern block. Closure of this eastern margin led to a Cambrian active margin (Sierra Norte arc) along the western margin of the eastern block in which magmatism reworked the same crustal block. Consumption of a ridge segment (input of OIB signature mafic magmas) which controlled granulite-facies metamorphism led to a final collision (Pampean orogeny) with the western Mesoprotrozoic block. Sm?CNd results for the metamorphic basement suggest that the T DM age interval of 1.8?C1.7?Ga, which is associated with the less radiogenic values of ??Nd(540) (?6 to ?8), can be considered as the mean average crustal composition for the Eastern Sierras Pampeanas. Increasing metamorphic grade in rocks with similar detrital sources and metamorphic ages like in the Sierras de Córdoba is associated with a younger T DM age and a more positive ??Nd(540) value. Pampean pre-540?Ma granitoids form two clusters, one with T DM ages between 2.0 and 1.75?Ga and another between 1.6 and 1.5?Ga. Pampean post-540?Ma granitoids exhibit more homogenous T DM ages ranging from 2.0 to 1.75?Ga. Ordovician re-activation of active margin along the western part of the block that collided in the Cambrian led to arc magmatism (Famatinian orogeny) and related ensialic back-arc basin in which high-grade metamorphism is related to mid-crustal felsic plutonism and mafic magmatism with significant contamination of continental crust. T DM values for the Ordovician Famatinian granitoids define a main interval of 1.8?C1.6, except for the Ordovician TTG suites of the Sierras de Córdoba, which show younger T DM ages ranging from 1.3 to 1.0?Ga. In Devonian times (Achalian orogeny), a new subduction regime installed west of the Eastern Sierras Pampeanas. Devonian magmatism in the Sierras exhibit process of mixing/assimilation of depleted mantle signature melts and continental crust. Achalian magmatism exhibits more radiogenic ??Nd(540) values that range between 0.5 and ?4 and T DM ages younger than 1.3?Ga. In pre-Devonian times, crustal reworking is dominant, whereas processes during Devonian times involved different geochemical and isotopic signatures that reflect a major input of juvenile magmatism. 相似文献
42.
Large-scale assessment of flood risk and the effects of mitigation measures along the Elbe River 总被引：2，自引：1，他引：1
The downstream effects of flood risk mitigation measures and the necessity to develop flood risk management strategies that
are effective on a basin scale call for a flood risk assessment methodology that can be applied at the scale of a large river.
We present an example of a rapid flood risk assessment methodology for the Elbe River. A 1D hydraulic routing model is extended
by including the effect of planned (regulated and unregulated) and unintended retention (dike breaches) on the peak water
levels. We further add an inundation model for dike breaches due to dike overtopping and a macroscale economic approach to
assess the flood damage. The flexible approach to model the effects of measures by means of volume storage functions allows
for rapid assessment of combinations of retention measures of various proposed dimensions and at multiple locations. The method
allows for the comparison of the flood risk at the scale of the main river trajectory, which has not been possible for the
Elbe River to date. The model is applied to a series of exemplary flood risk mitigation measures to show the downstream effects
and the additive effects of combinations of measures on the flood risk along the river. We further demonstrate the increase
in the downstream flood risk resulting from unilateral decisions to increase the dike height at upstream locations. As expected,
the results underline the potential effectiveness of increased retention along the river. The effects of controlled retention
at the most upstream possible location and largest possible extent generate the most pronounced reduction of average annual
damage. As expected, the effect of uncontrolled retention with dike relocations is significantly lower. 相似文献
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44.
Bjoern Malte Schaefer Marian Douspis Nabila Aghanim 《Monthly notices of the Royal Astronomical Society》2009,397(2):925-932
The subject of this paper is a quantification of the impact of uncertainties in bias and bias evolution on the interpretation of measurements of the integrated Sachs–Wolfe (ISW) effect, in particular on the estimation of cosmological parameters. We carry out a Fisher matrix analysis for quantifying the degeneracies between the parameters of a dark energy cosmology and bias evolution, for the combination of the PLANCK microwave sky survey with the EUCLID main galaxy sample, where bias evolution b ( a ) = b 0 + (1 − a ) ba is modelled with two parameters b 0 and ba . Using a realistic bias model introduces a characteristic suppression of the ISW spectrum on large angular scales, due to the altered distance-weighting functions. The errors in estimating cosmological parameters if the data with evolving bias is interpreted in the framework of cosmologies with constant bias are quantified in an extended Fisher formalism. We find that the best-fitting values of all parameters are shifted by an amount comparable to the statistical accuracy: the estimation bias in units of the statistical accuracy amounts to 1.19 for Ωm , 0.27 for σ8 and 0.72 for w for bias evolution with ba = 1 . Leaving ba open as a free parameter deteriorates the statistical accuracy, in particular on Ωm and w . 相似文献
45.
Malte Selugge 《中国勘察设计》2007,(3):68-68
中国是一个大国，北京是一个很大的城市。它是中国最后一个皇朝所在地，它有非常丰富的景观，正如紫禁城一样风格独特。这个城市拥有很庞大的建筑结构，而很多的建筑那是四散在城市当中。目前，投资者受到市场的驱动，在各个城市的街道上进行激烈的争夺。那么，我们来看看中国的景观设计。我想引用一位著名的设计师1996年所讲的一种全新的景观设计理念， 相似文献
46.
Frank Dethlefsen Rainer Meckenstock Malte K. Veehmayer Andreas Dahmke 《Environmental Geology》2004,46(6-7):896-904
Different methods were compared to evaluate the oxidation capacity of ferric iron in column studies. The specific adsorption of the reactive tracer phosphate on the Fe(III) oxide surface was used as an alternative approach to determine the oxidation capacity utilizing the linear correlation between the long-term extent of Fe(III) reduction and the specific surface area of the oxide. Although a low crystalline form of ferric iron (two-line ferrihydrite) was used as electron acceptor and toluene as a carbon source, only 31 and 24% respectively of the total iron was reduced by Geobacter metallireducens in parallel experiments. The results of the phosphate tracer tests were in good agreement with the Fe(III) that was actually reduced and the microbially oxidized toluene. The oxidation capacity of ferric iron is therefore overestimated by the chemical extraction methods, which completely dissolve the ferrihydrite and neglect surface-dependent limitations. 相似文献
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48.
Alexander Gerst Matthias Hort Philip R. Kyle Malte Vöge 《Journal of Volcanology and Geothermal Research》2008
We used a novel system of three continuous wave Doppler radars to successfully record the directivity of i) Strombolian explosions from the active lava lake of Erebus volcano, Antarctica, ii) eruptions at Stromboli volcano, Italy, and iii) a man-made explosion in a quarry. 相似文献
49.
Malte Thoma Christoph Mayer Klaus Grosfeld 《Earth and Planetary Science Letters》2008,269(1-2):242-247
Subglacial lakes provide unique habitats, but the exact nature of physical and geochemical conditions are still a matter of debate and await direct sampling of water. Due to its isolation from external atmospheric forcing other environmental parameters influence the flow characteristics within the lake. In this study we use an improved treatment of the physical processes at the ice–water boundary interface to identify and quantify the impact of (1) the geothermal heat flux, (2) the heat flux from the lake into the ice, (3) the influence of the salinity of the lake water, and (4) the ice thickness on the size of the freezing area and the freeze/melt rates. We show that the modelled basal mass imbalance (that is the produced melt water minus the re-frozen water) depends on the geothermal heating as well as the heat flux into the ice. The circulation and the temperature distribution within subglacial Lake Vostok are rather stable against variations of geothermal heat flux, heat flux into the ice sheet, salinity of the lake, and small changes of the ice thickness above the lake. However, the flow regime for any subglacial lake with less than 2000 m ice thickness above, will be substantially different from those that experience higher pressures. This is because the buoyancy–temperature relationship reverses at this depth. 相似文献
50.
Malte?MüllerEmail author Josef?Y.?Cherniawsky Michael?G.?G.?Foreman Jin-Song?von?Storch 《Ocean Dynamics》2014,64(2):159-177
The seasonal cycle of the main lunar tidal constituent M 2 is studied globally by an analysis of a high-resolution ocean circulation and tide model (STORMTIDE) simulation, of 19 years of satellite altimeter data, and of multiyear tide-gauge records. The barotropic seasonal tidal variability is dominant in coastal and polar regions with relative changes of the tidal amplitude of 5–10 %. A comparison with the observations shows that the ocean circulation and tide model captures the seasonal pattern of the M 2 tide reasonably well. There are two main processes leading to the seasonal variability in the barotropic tide: First, seasonal changes in stratification on the continental shelf affect the vertical profile of eddy viscosity and, in turn, the vertical current profile. Second, the frictional effect between sea-ice and the surface ocean layer leads to seasonally varying tidal transport. We estimate from the model simulation that the M 2 tidal energy dissipation at the sea surface varies seasonally in the Arctic (ocean regions north of 60°N) between 2 and 34 GW, whereas in the Southern Ocean, it varies between 0.5 and 2 GW. The M 2 internal tide is mainly affected by stratification, and the induced modified phase speed of the internal waves leads to amplitude differences in the surface tide signal of 0.005–0.0150 m. The seasonal signals of the M 2 surface tide are large compared to the accuracy demands of satellite altimetry and gravity observations and emphasize the importance to consider seasonal tidal variability in the correction processes of satellite data. 相似文献