Wide binaries in the Pleiades     

P. Brosche  M. Hoffmann 《Astrophysics and Space Science》1979,63(2):467-477

The number and distribution of visual binaries in the Pleiades agree with the frequencies in the solar neighbourhood, except for an apparent deficiency of systems with faint components.  相似文献   

Early-type galaxies in low-density environments     

Harald Kuntschner †  Russell J. Smith ‡  Matthew Colless  Roger L. Davies  Raven Kaldare  Alexandre Vazdekis 《Monthly notices of the Royal Astronomical Society》2002,337(1):172-198

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Predicting storm runoff from different land‐use classes using a geographical information system‐based distributed model     

Y. B. Liu  S. Gebremeskel  F. De Smedt  L. Hoffmann  L. Pfister 《水文研究》2006,20(3):533-548

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   

Structural states of Mg-cordierite I: Order parameters from synchrotron X-ray and NMR data     

Andrew Putnis  Ekhard Salje  Simon A. T. Redfern  Colin A. Fyfe  Harald Strobl 《Physics and Chemistry of Minerals》1987,14(5):446-454

The hexagonal to orthorhombic phase transition in synthetic Mg-cordierite has been studied by (i) measuring the spontaneous strain associated with the transition using Synchrotron X-ray powder diffraction and (ii) measuring the degree of Al, Si order in terms of the number of Al-O-Al bonds per formula unit using solid state NMR spectroscopy. This defines the two order parametersQ andQ _od respectively, and their relationship as a function of annealing temperature and time is used to define the structural states of cordierite during the ordering sequence. The formation of modulated hexagonal cordierite within which a high degree of Al, Si order can be attained, results in a strongly non-linear relationship betweenQ andQ _od .The transition from modulated to orthorhombic cordierite is strongly first-order under all temperature conditions studied and involves a large step inQ, whileQ _od changes continuously throughout the ordering sequence with no marked discontinuity at the phase transition. The lattice distortion, traditionally defined in cordierite by the Δ index provides no full information on the degree of Al, Si order in anhydrous Mg-cordierite, and both order parameters must be used to define its structural state. Transmission electron microscopy has been used to study the mechanism of the transformation from hexagonal to modulated to orthorhombic cordierite.  相似文献   

Die Glaukophangesteine,ihre stofflichen Äquivalente und Uniwandlungsprodukte in Nordcalabrien (Süditalien)     

Dr. Christoph Hoffmann 《Contributions to Mineralogy and Petrology》1970,27(4):283-320

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   

Barite deposits of the “Montagne Noire”, Southern France     

Thomas Hoffmann 《Mineralium Deposita》1969,4(3):260-274

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.

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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.

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...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   

The occurrence of bisulfite-aldehyde addition products in fog- and cloudwater     

J. W. Munger  D. J. Jacob  M. R. Hoffmann 《Journal of Atmospheric Chemistry》1984,1(4):335-350

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   

Synoptic survey on dissolved trace metal levels in Baltic surface waters     

Klaus Kremling  Harald Petersen 《Marine pollution bulletin》1984,15(9):329-334

A total of 95 surface water samples (6 m depth) was collected during a transect from the Bothnian Bay to Kiel between 28 August and 5 September 1982. This report presents the dissolved trace metal (<0.4 μm) and the associated hydrographic and nutrient data. Except for aluminium, all other metals determined (Zn, Cd, Cu, Ni, Fe, Mn) showed a rather homogeneous distribution within the subregions, with highest values in the Bothnian Bay (except for Mn) and net variations of the individual samples of about 20%. Cadmium, copper and nickel reveal conservative behaviour when values from this study and literature data from the Kattegat and North Sea area are plotted against salinity.  相似文献   

Trend surface analysis of some physical properties of alkali (sodic) amphiboles     

Chr. Hoffmann  K. Katz 《Lithos》1982,15(1):17-25

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Neoproterozoic tectonothermal evolution of the Central Eastern Desert, Egypt: a slow velocity tectonic process of core complex exhumation     

Harald Fritz  David R. Dallmeyer  Eckart Wallbrecher  Jürgen Loizenbauer  Georg Hoinkes  Peter Neumayr  Ali A. Khudeir 《Journal of African Earth Sciences》2002,34(3-4)

Regional cooling in the course of Neoproterozoic core complex exhumation in the Central Eastern Desert of Egypt is constraint by ⁴⁰Ar/³⁹Ar ages of hornblende and muscovite from Meatiq, Sibai and Hafafit domes. The data reveal highly diachronous cooling with hornblende ages clustering around 580 Ma in the Meatiq and the Hafafit, and 623 and 606 Ma in the Sibai. These ⁴⁰Ar/³⁹Ar ages are interpreted together with previously published structural and petrological data, radiometric ages obtained from Neoproterozoic plutons, and data on sediment dynamics from the intramontane Kareim molasse basin. Early-stage low velocity exhumation was triggered by magmatism initiated at 650 Ma in the Sibai and caused early deposition of molasses sediments within rim synforms. Rapid late stage exhumation was released by combined effect of strike-slip and normal faulting, exhumed Meatiq and Hafafit domes and continued until 580 Ma. We propose a new model that adopts core complex exhumation in oblique island arc collision-zones and includes transpression combined with lateral extrusion dynamics. In this model, continuous magma generation weakened the crust leading to facilitation of lateral extrusion tectonics. Since horizontal shortening is balanced by extension, no major crustal thickening and no increase of potential energy (gravitational collapse) is necessarily involved in the process of core complex formation. Core complexes were continuously but slowly exhumed without creating a significant mountain topography.  相似文献