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171.
A method is presented to evaluate the storm runoff contributions from different land‐use class areas within a river basin using the geographical information system‐based hydrological model WetSpa. The modelling is based on division of the catchment into a grid mesh. Each cell has a unique response function independent of the functioning of other cells. Summation of the flow responses from the cells with the same land‐use type results in the storm runoff contribution from these areas. The model was applied on the Steinsel catchment in the Alzette river basin, Grand Duchy of Luxembourg, with 52 months of meteo‐hydrological measurements. The simulation results show that the direct runoff from urban areas is dominant for a flood event compared with runoff from other land‐use areas in this catchment, and this tends to increase for small floods and for the dry‐season floods, whereas the interflow from forested, pasture and agricultural field areas contributes to recession flow. It is demonstrated that the relative contribution from urban areas decreases with flow coefficient, that cropland relative contribution is nearly constant, and that the relative contribution from grassland and woodland increases with flow coefficient with regard to their percentage of land‐use class areas within the study catchment. Copyright © 2005 John Wiley & Sons, Ltd.  相似文献   
172.
In the southern Apennin (= northern part of the region dealt with) and the Coasta Chain (= southern part) there are metabasalts wich are classified in the northern part as:
  1. Glaucophane rocks of the albite-lawsonite-glaucophane-subfacies with the assemblage glaucophane + pumpellyite + lawsonite ±albite ±aragonite ±muscovite (7 rock analyses, 8 mineral analyses). These rocks are conceived as relics of an older burial metamorphism.
  2. Rocks with pumpellyite and chlorite or also chlorite alone, that are interpreted as reaction rims between the metastable glaucophane rocks and the country rock (phyllites, quartzites). The assemblages pumpellyite + chlorite and chlorite alone are to be found (2 rock analyses and 2 mineral analyses).
  3. Rocks with lawsonite and/or epidote belong to the same mineral facies as the country rock: a facies similar to the greenschist facies (called “lawsonite-albite-chlorite-subfacies”) which is characterized by the assemblages lawsonite + albite + chlorite ±calcite and also epidote ±lawsonite + albite + chlorite ± muscovite. These types are attributed to a younger dynamo-metamorphism (2 rock analyses).
In the southern part, the metabasalts can be found only as rocks with epidote and/or lawsonite, a metamorphism with more than one event cannot be proved petrologically (3 rock analyses). Equations of the observed mineral reactions are given. The transitions of one facies into another are represented in the pseudo-quaternary system Al2O3-CaO-Na2O · Al2O3-2 Fe2O3 + FeO + MnO + MgO-(H2O). The pressure-temperature conditions are estimated on the basis of published experimental data (300° C and 6–7 kb for the glaucophane rocks; 400° C and about 6 kb for the rocks with lawsonite and/or epidote) and are compared with geologic facts.  相似文献   
173.
Several small barite deposits of Devonian age are known in the Monts de Cabrières region, Montagne Noire (southern France). A field and laboratory investigation of these stratabound deposits showed their possible diagenetic origin and a limited economic value.
Zusammenfassung De petits gisements de barytine du Dévonien dans les Monts de Cabrières (Montagne Noire, France) ont été étudié en détail sur le terrain et au laboratoire. Les observations ont apporté des critères pour une explication génétique de ces gisements «stratiformes». Ils indiquent que les concentrations minérales se sont effectuées par un processus de sécrétion au cours de la diagenèse. L'importance économique de ces gisements est limitée.


...es ist zwar nicht sinnlos, aber doch etwas unlogisch, wenn man von vornherein nicht versucht, eine Lagerstätte in ihre Umgebung auf die wahrscheinlichste Art einzugliedern, sondern sie unbedingt einem ganz fremden, zunächst nicht von selbst verständlichen Bildungsvorgang zuordnen will. H. Schneiderhöhn (1954)  相似文献   
174.
Elevated concentrations of S(IV) and formaldehyde were observed in fog- and cloudwater at sites in California. The highest concentrations (up to 3 mM S(IV) and 0.7 mM CH2O) were measured at Bakersfield, during a prolonged period of repeated fog. In Bakersfield [S(IV)] generally exceeded [CH2O], while in the Los Angeles area the reverse was observed. The lowest concentrations of both species were observed at marine and high altitude sites away from local emissions. Equilibrium computations indicate that high concentrations of S(IV) cannot be achieved without the formation of S(IV)-RCHO adducts.  相似文献   
175.
176.
177.
Within the southern part of the Sierra Pampeanas (the Sierra de San Luis, Argentina), a series of extensive intrusive bodies are regarded to post-date the Famatinian cycle but were emplaced during the Achalian, a period of heterogeneous deformation along crustal scale fault zones. The largest of those is the Las Chacras-Potrerillos batholith that is situated at the northern end of the transpressive, sinistral Guzmán shear zone. This composite pluton exhibits three sub-domains that comprise two granitoid sub-units each: The southern Potrerillos stock (muscovite-bearing red granite and biotite-bearing red granite) and the central (biotite porphyritic granite and giant porphyritic granite) and northern domain (equigranular granite and porphyritic granite) of the Las Chacras stock. The crystallisation ages of the biotite porphyritic granite is around 381 Ma (U/Pb on zircons and Pb/Pb on sphene), while the host rock was already cooled below 350 °C at 420 Ma. Thermal modelling approaches favour a pulsed intrusion with a duration of 1.5 Ma. The emplacement was followed by rapid cooling below the muscovite cooling temperature. Biotite cooling ages in different sub-units reflect either a long-lasting cooling history of approximately 30 Ma (which is supported by the modelling) or a reheating effect at around 350 Ma. Devonian-age determinations on the fault rocks and granitoids point to a syn-tectonic emplacement of the batholith. The pluton is interpreted to be positioned at the crossover of sinistral shear zones. The origin of this NNE directed extensional setting in a transpressive regime seems to be related to the transfer of displacement along a secondary set of NNW-trending sinistral faults. The final emplacement is due to a subsequent ballooning of the batholith following the direction of space creation. This model is based on the relative timing of the emplacement sequence and macroscopically visible planar fabrics in the field as well as magnetic fabric data. Our results indicate that the emplacement is syn-kinematic with respect to the Achalian deformation event.  相似文献   
178.
A magnetic study was carried out on lacustrine sediments from the Zoigê basin, Tibetan Plateau, in order to obtain a better understanding of palaeoclimatic changes there. Gyromagnetic remanence (GRM) acquisition is unexpectedly observed during static three-axis alternating field (AF) demagnetization in about 20 per cent of a large number of samples. X-ray diffraction (XRD) analysis on a magnetic extract clearly shows that greigite is the dominant magnetic mineral carrier. Scanning electron microscopy (SEM) reveals that the greigite particles are in the grain size range of 200–300  nm, possibly in the single-domain state. Greigite clumps of about 3  μm size are sealed by silicates. Fitting of XRD peaks yields a crystalline coherence length of about 15  nm, indicating that the particles seen in the SEM are polycrystalline.
  GRM intensities of most samples are of the same order as the NRM, while others show much stronger GRM although their magnetic properties are similar. Variation of the demagnetization sequence confirms that GRM is mainly produced perpendicular to the AF direction. The anisotropy direction can be derived from GRM, but more systematic studies are needed for detailed conclusions. An attempt to correct for GRM failed due to high GRM intensities and because smaller GRM acquisition was also found along the demagnetization axis. Behaviours of acquisition and AF demagnetization of GRM are comparable with those of NRM, ARM, IRM, indicating fine grain sizes of remanence carriers.  相似文献   
179.
The present paper summarises results on the emission of biogenicvolatile organic compounds (BVOC) achieved within the frame of thenational `German Tropospheric Research Programme' (TFS) between 1997 and2000. Field measurements were carried out at the meteorologicalmonitoring station `Hartheimer Wald' located in the vicinity of Freiburg(upper Rhine valley), Germany, within a pine plantation dominated byScots pine (Pinus sylvestris L.). The measured BVOC emissionrates were used to determine the daily and seasonal variation of BVOCemission and its dependence on important meteorological and plantphysiological parameters. In parallel, laboratory experiments usingyoung trees of pine (P. sylvestris), poplar (Populustremula ×P. alba) and pedunculate oak (Quercusrobur L.) were performed, and the influence of abiotic (e.g.,light, temperature, seasonality, flooding) factors on the biosynthesisand emission of BVOC was quantified. Based on these data, emissionalgorithms were evaluated and a process-oriented numerical model for thesimulation of the isoprene emission by plants was developed. Inaddition, newly calculated land use and tree species distributions wereused for the calculation of an actual BVOC emission inventory ofGermany.  相似文献   
180.
Identification of greigite in lake sediments and its magnetic significance   总被引:5,自引:1,他引:5  
Detailed rock magnetic investigations and mineralogical analysis were conducted on lacustrine sediments recovered from Zoigê Basin, eastern Tibetan Plateau. Greigite, with fine and homogenous grain size, is found as a main magnetic carrier, which is suspected to be of biochemical origin. In contrast to some reports, greigite within the sediments is not oxidized even after exposure to air for a few years, which could be due to the fact that greigite is sealed by silicate.  相似文献   
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