Some remarks on geodetic reference systems in Eastern Europe in preparation of a uniform European geoid     

Johannes Ihde 《Journal of Geodesy》1993,67(2):81-85

In view of a uniform European geoid determination with centimeter accuracy the situation of the geodetic reference systems in Eastern Europe is described. For the necessary transformations into a uniform reference system the relevant relations are specified.  相似文献   

Development of competence for competitiveness     

Johannes Moe 《Marine pollution bulletin》1994,29(6-12):562-565

This paper presents an integrated approach to the development of a company's competence. The discussion, which has special relevance for large companies, covers competitiveness, competence in general, individual knowledge and expertise, institutional competence, capability, and mobility. An example is presented which illustrates a co-ordinated effort to increase the environmental competence in Statoil. Much of the reasoning here has the most direct focus on technological competence and development, but it is believed to be equally relevant to the other functions in the company.  相似文献   

On the mechanisms of cation diffusion processes in ternary feldspars     

H. Behrens  W. Johannes  H. Schmalzried 《Physics and Chemistry of Minerals》1990,17(1):62-78

Cation diffusion processes have been studied in single crystals of intermediate plagioclase and albite composition by tracer-diffusion experiments and optical absorption spectroscopy. Tracer-diffusivities were determined by the residual activity method, using the radioactive isotopes ²²Na, ⁴⁵Ca and ⁵⁹Fe. In most cases, diffusion experiments were performed at 1 bar, at controlled oxygen activity and at temperatures between 750 and 1300°C. The obtained Na-diffusivities for plagioclases were much smaller then previously determined for albite. This indicates a strong composition dependence of Na-diffusion. In contrast, Ca-diffusivity in albite does not differ very much from that in intermediate plagioclases. The relative diffusivities determined for plagioclase of composition An62 at 1200° C (CO/CO₂ =50∶50) were D _infNa ^sup* ∶D _infFe ^sup* ∶D _infCa ^sup* =5000∶10∶1. Despite the an isotropic structure of feldspars, no difference was found for Na-and Ca-diffusion normal to (001) and normal to (010). Water pressure of 2 kbar has no influence on the Na-diffusivity. In contrast to the Ca-diffusion, a dependence on oxyggen activity was found for Na-and Fe-diffusion. Fe-diffusivity increases with decreasing oxygen activity. This can be correlated to changes in oxidation state of iron dissolved in the plagioclases. Optical absorption spectroscopy shows that iron is oxidized in the plagioclases by annealing in air. This effect can be reversed by annealing at reducing conditions. A model is proposed to explain the oxidation of iron by a chemical diffusion process in which A-vacancies are formed by out-diffusion of Na⁺. Preannealing of samples in air gives a temperature independent decrease of Na-diffusivity by a factor of about 2.5. This effect is explained with help of a simple disorder model for A-cations in ternary feldspars. It is concluded that Na⁺ diffuses via interstitials and that the A-vacancy concentration in the plagioclases is controlled extrinsically, probably by dissolved SiO₂.  相似文献   

Phase equilibria and compositions of Fe-Mg-Al minerals and melts in water-saturated peraluminous granitic systems     

Jacek Puziewicz  Wilhelm Johannes 《Contributions to Mineralogy and Petrology》1988,100(2):156-168

Phase assemblages and phase compositions were studied experimentally in water-saturated, biotite-bearing peraluminous granitic melts as a function of alumina excess and temperature. The runs were performed at 2 and 5 kbars under NNO buffer. Biotite was stable only in composition containing 5% of normative corundum; it coexisted with cordierite and hercynite at 2 kbars and with hercynite at 5 kbars. In composition containing 10% of normative corundum biotite was not observed; abundant cordierite and hercynite were the only Fe-Mg-Al minerals. These relationships show that, at constant pressure, the amount of cordierite increases with increasing excess of alumina. Simultaneously the stability of biotite decreases due to preferential partitioning of Mg into cordierite and Fe into biotite. Besides the distribution of Fe, Mg and Al among the coexisting solid phases, solubility of these elements in the melts is given. Below 900° C melts are poor in iron and magnesium and correspond, in terms of these elements, to leucogranites. It is suggested that the leucogranitic magmas, such as parental magmas of European Hercynian and Himalayan leucogranites, must have been formed through highly efficient separation of partial melt from restite, in which ferromagnesian components are concentrated. Peraluminous granites rich in ferromagnesian minerals originate supposedly from restite-bearing magmas.  相似文献   

V. Morphotektonik und Neogenbuchten in Ost-Bulgarien     

Johannes F. Gellert 《International Journal of Earth Sciences》1930,21(4):209-217

Ohne ZusammenfassungAuf der Hauptversammlung der Geologischen Vereinigung in Frankfurt am 5. I. 30 vorgetragen.  相似文献   

Die eigenartigen Verwitterungs- und Landschaftsformen des Dikilitaš-Sandsteines in Nordost-Bulgarien     

Johannes F. Gellert 《International Journal of Earth Sciences》1932,23(3-4):173-178

Ohne Zusammenfassung  相似文献   

Einige Ergebnisse der geologischen Landesaufnahme in den Westtiroler Zentralalpen     

Wilhelm Hammer 《International Journal of Earth Sciences》1925,16(2):147-160

Ohne Zusammenfassung  相似文献   

I. Erdöl Ergebnisse der erdölgeologischen Erforschung Nordwestdeutschlands 1932–1947, ein Überblick     

Alfred Bentz  A. Meyer-Gürr  Helmut Fahrion  Walter Rühl  Wilhelm Kehrer  Hermann Deecke  H. Schlüter  Rolf Behrmann  Hans Weber  Herbert Lögters  Oswald Schmidt 《International Journal of Earth Sciences》1948,35(2):167-170

Ohne Zusammenfassung  相似文献   

IV. Stratigraphie Die fazielle Einstufung fossilführender Sedimente     

Hermann Schmidt  Karl Hoffmann  Erich Brand  Wolfgang Schott  Otto Seitz  Johannes Wolburg  Franz Bettenstaedt  F. E. Hecht  Hilmar Schumann  F. Heidorn 《International Journal of Earth Sciences》1948,35(2):175-178

Ohne Zusammenfassung  相似文献   

Gedrillte Asteriten im Rosenquarz und Granat     

Wilhelm Maier 《Contributions to Mineralogy and Petrology》1951,2(5):428-431

Ohne Zusammenfassung  相似文献