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161.
Magdalena Scheck Ulf Bayer Volker Otto Juliette Lamarche Dirk Banka Tim Pharaoh 《Tectonophysics》2002,360(1-4):281-299
The Elbe Fault System (EFS) is a WNW-striking zone extending from the southeastern North Sea to southwestern Poland along the present southern margin of the North German Basin and the northern margin of the Sudetes Mountains. Although details are still under debate, geological and geophysical data reveal that upper crustal deformation along the Elbe Fault System has taken place repeatedly since Late Carboniferous times with changing kinematic activity in response to variation in the stress regime. In Late Carboniferous to early Permian times, the Elbe Fault System was part of a post-Variscan wrench fault system and acted as the southern boundary fault during the formation of the Permian Basins along the Trans-European Suture Zone (sensu [Geol. Mag. 134 (5) (1997) 585]). The Teisseyre–Tornquist Zone (TTZ) most probably provided the northern counterpart in a pull-apart scenario at that time. Further strain localisation took place during late Mesozoic transtension, when local shear within the Elbe Fault System caused subsidence and basin formation along and parallel to the fault system. The most intense deformation took place along the system during late Cretaceous–early Cenozoic time, when the Elbe Fault System responded to regional compression with up to 4 km of uplift and formation of internal flexural highs. Compressional deformation continued during early Cenozoic time and actually may be ongoing. The upper crust of the Elbe Fault System, which itself reacted in a more or less ductile fashion, is underlain by a lower crust characterised by low P-wave velocities, low densities and a weak rheology. Structural, seismic and gravimetric data as well as rheology models support the assumption that a weak, stress-sensitive zone in the lower crust is the reason for the high mobility of the area and repeated strain localisation along the Elbe Fault System. 相似文献
162.
163.
Dr. Ulf Zischinsky 《International Journal of Earth Sciences》1968,58(2):974-983
Zusammenfassung Die Begriffe Bergzerreißung und Talzuschub kennzeichnen die morphologischen Auswirkungen großzügiger Hangbewegungen und zwar des Abriß- beziehungsweise des Fußbereiches.Die strukturellen Besonderheiten der Sackungen werden an besonders günstigen Beispielen deutlich: Dort bildet sich die Bewegung in einem mehrere hundert Meter mächtigen Hakenwerfen der ursprünglich steil talwärts fallenden Schichten ab, das nach oben noch in einen kaum verformten Bereich übergeht.Aus diesen Angaben läßt sich ein allgemein für Böschungen gültiger Deformationsplan ableiten, der bei Annahme einer linearen Verteilung der Scherbeanspruchung in der Vertikalen die Formulierung der festigkeitstheoretischen Eigenschaften des Materials Fels gestattet: Danach müssen wir dem Gebirge unter Oberflächenbedingungen erstens eine mit der Einspannung zunehmende Scherfestigkeit, die außerdem noch von der betrachteten Größenordnung abhängig ist, und zweitens ein Fließverhalten zuschreiben, das durch eine Potenzfunktion dargestellt wird.Auf Grund des Vergleiches mit Eis sind wir zu der Annahme berechtigt, daß dieses Fließgesetz auch für tiefere Krustenteile gültig ist.
The terms Bergzerreißung (mountain splitting) and Talzuschub (closing-up of the valleys) describe the morphological features of large down-hill movements. Their structural peculiarities are determined by a zone of internal rotation beneath a zone of only small internal deformation.From these data we can deduce a general plan of deformation of slopes. When assuming a linear distribution of shear stress they also allow the determination of the mechanical properties of rock masses.Comparing rock and ice in general we may conclude that these mechanical properties, mainly the flow law expressed by a power function, are valid also in deep parts of the earth's crust.
Résumé Les termes « Bergzerreißung » et « Talzuschub » désignent les effets morphologiques de forts mouvements de versants. Les particularités structurelles des affaisements de rochers se manifestent dans une zone de « rotation interne » sous une zone de faible déformation interne.De ces faits on peut déduire un plan général de déformation. L'hypothèse d'une répartition linéaire de la contrainte de cisaillement dans le sens vertical rend possible une détermination des propriétés méchaniques des rochers.D'une comparaison avec la glace nous pouvons tirer la conclusion que ces propriétés méchaniques, surtout la loi de fluage exprimée dans l'équation = ab ( = vitesse de déformation, = contrainte de cisaillement; a, b = paramètres), sont également valables dans les parties profondes de la croûte terrestre.
, . , . , , .相似文献
164.
The energy levels of MnO 6 9? clusters, with D 4h approximated and C 2v actual symmetry of the M 1 site of Mn3+-bearing andalusite, are calculated using the multiple scattering method. The energies of the electronic d-d transition of Mn3+ in the clusters with D 4h symmetry are calculated to be 6,000–7,000 cm?1 (5 B 1g → 5 A 1g ), ~18,000 cm?1 (5 B 1g → 5 B 2g ) and ~19,000 cm?1 (5 B 1g → 5 E g ). Apart from a splitting of the 5 E g -level into two levels separated by 300–350 cm?1, no significant changes of these transition energies are noted for the corresponding cluster with C 2v symmetry. The calculated transition energies give a good fit to the structure of the optical absorption spectra of Mn3+-bearing andalusites and support recent assignments of the major absorption bands observed in these spectra. 相似文献
165.
Six natural chloritoid crystals with Fe2+ and Fe3+ contents ranging from 4.15 to 12.81 and from 0.411 to 0.849g-atoms/l, respectively, as determined by means of microprobe and Mössbauer techniques, served as reference material to develop non-destructive microscope-spectrophotometric methods for quantitative Fe2+ – Fe3+ determinations in chloritoids from unpolarized spectra of (001) platelets. Fe2+ concentrations in g-atom/l can be obtained from [ [Fe3+]=C1xD1/t where D1 = log10(I0/I at 28,000 cm-1 and t=crystal thickness in cm; C1 is a conttant that may be influenced somewhat by experimental conditions and is found to be 0.002289 with the experimental set-up used in this study. Fe2+ concentrations in g-atom/l can be obtained from [Fe2+]=C1xD1/D1-C3 with D2=log10(I0/I) at 16,300 cm?1 and constants C4 = 45.36 and C5 = 3.540. Due to the uncertainties in absorbance measurements, D1 and D2 and the thickness measurements, the accuracies are ±0.05 and ±0.15 g-atom/l for [Fe3+] and [Fe2+], respectively. The determinations may be carried out on chloritoid grains in normal thin sections with an areal resolution of ~10 μm. 相似文献
166.
Turbulence mechanisms at an agricultural site 总被引:8,自引:0,他引:8
An extensive set of turbulence data from the 3- and 12-m heights taken over an agricultural site (Marsta, Sweden) are analyzed and compared with data from ideal sites.In unstable air, Monin-Obukhov similarity is found to be valid for the non-dimensional gradients of wind,
m
, temperature,
h
, and humidity,
e
, for (only a few data), for
T
/|T
*|,/
E
/|E
*| and for the non-dimensionalized inertial subrange spectra of temperature and humidity. Where comparison is possible, the unstable data also agree with those found in the Kansas study, with one remarkable exception, the inertial subrange constant of the temperature spectrum, 1, being only 0.39, compared to the value 0.80 found at the Kansas site.On the stable side, most similarity predictions break down, with most of the data differing systematically from the corresponding Kansas results, the only exception being . The inertial subrange constants for temperature, 1, and for humidity, 1 are found to have the same values, 0.39 and 0.30, respectively, as they do on the unstable side. Remarkable similarity is found for the shape of the stable u- and - and e-spectra. In addition, this shape is found to be identical with that found in Kansas. The peak wavelength of the stable u-, and -spectra is found to be about four times larger than it is for the corresponding Kansas spectra. This is interpreted to be a result of the increased macro-roughness at the Marsta site as compared with that at the Kansas site. A possible explanation for the low 1-value is discussed, suggesting that 1 is not a universal constant, but instead dependent on the turbulent structure. 相似文献
167.
Non-dimensional wind and temperature profiles in the atmospheric surface layer: A re-evaluation 总被引:5,自引:12,他引:5
Ulf Högström 《Boundary-Layer Meteorology》1988,42(1-2):55-78
Previous results of non-dimensional wind and temperature profiles as functions of ( = z/L) show systematic deviations between different experiments. These discrepancies are generally believed not to reflect real differences but rather instrumental shortcomings. In particular, it is clear that flow distortion has not been adequately treated in most previous experiments. In the present paper, results are presented from a surface-layer field experiment where great care was taken to remove any effects from this kind of error and also to minimize other measuring errors. Data from about 90 30-min runs with turbulence measurements at three levels (3, 6, and 14 m) and simultaneous profile data have been analysed to yield information on flux-gradient relationships for wind and temperature.The flux measurements themselves show that the fluxes of momentum and sensible heat are constant within ± 7% on average for the entire 14 m layer in daytime conditions and when the stratification is slightly stable. For more stable conditions, the flux starts to decrease systematically somewhere in the layer 6 to 14 m. From a large body of data for near-neutral conditions (¦¦ 0.1), values are derived for von Kármán's constant: 0.40 ± 0.01 and for
h
at neutrally, 0.95 ± 0.04. The range of uncertainty indicated here is meant to include statistical uncertainty as well as the effect of possible systematic errors.Data for
m
and
h
for an extended stability range (1 > > – 3) are presented. Several formulas for
m
and
h
appearing in the literature have been used in a comparative study. But first all the formulas have been modified in accordance with the following assumptions: = 0.40 and (
h
) = 0 = 0.95; deviations from this result in the various studies are due to incomplete correction for flow distortion. After new corrections are introduced, the various formulas were compared with the present measurements and with each other. It is found that after this modification, the most generally used formulas for
m
and
h
for unstable conditions, i.e., those of Businger et al. (1971) and Dyer (1974) agree with each other to within ± 10% and with the present data. For stable conditions, the various formulas still disagree to some extent. The conclusion in relation to the present data is not as clear as for the unstable runs, because of increased scatter. It is, however, found that the modified curve of Businger et al. (1971) for
h
fits the data well, whereas for
m
, Dyer's (1974) curve appears to give slightly better agreement. 相似文献
168.
169.
Mafic intrusive rocks (1.79–1.78 Ga) of the Transscandinavian Igneous Belt (TIB) and the c. 1.87 Ga Hedesunda Igneous Complex in the Fennoscandian Shield of south‐central Sweden were studied using whole‐rock and isotope geochemistry. Rock types vary from gabbros/norites (and leucogabbros) to quartz diorites, with Mg# between 76 and 49, and wt% SiO2 between 43.6 and 59.7, indicating some variation in evolutionary levels and variable cumulus components. Geochemical signatures are calc‐alkaline to shoshonitic, large ion lithophile elements and light rare earth elements enriched and high‐field strength elements depleted of continental‐arc type. εNd(t) ranges between +1.0 and +2.7, and 87Sr/86Sr(t) between 0.7020 and 0.7038. There is no systematic correlation between chemical parameters and isotope ratios. These isotopic data overlap with other mafic plutonic TIB rocks; samples from the Dala Province (DP) tend to overlap with the c. 1.7 Ga basic Dala lavas of TIB at slightly elevated relative Sr/Nd ratios. With two exceptions, the εNd(t) of +1 to +2 conform to an isotopically ‘mildly depleted’ source, typical for mafic TIB rocks and many Svecofennian rocks in the region. Reported values above εNd(t) +2.0 are scarce in the TIB. Mantle sources represent depleted mantle wedge material that was enriched by fluids/melts not long before (TDM c. 2.0 Ga), that is during subduction in the preceding Svecofennian (2.0–1.87 Ga) and/or during the TIB‐0&1 event (1.85–1.78 Ga). The palaeotectonic settings inferred are active continental margins; N–S‐directed convergence at 1.87 Ga and E–W‐directed at 1.79–1.78 Ga. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
170.
Abermann Jakob Eckerstorfer Markus Malnes Eirik Hansen Birger Ulf 《Natural Hazards》2019,97(2):517-534
Natural Hazards - On 11 April 2016 we observed high slushflow and wet snow avalanche activity at the environmental monitoring station Kobbefjord in W-Greenland. Snow avalanches released as a result... 相似文献