Editors' note     

Giuliano F. Panza  Stephan Mueller  Erhard Wielandt 《Pure and Applied Geophysics》1980,118(2):1191-1191

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A crustal section across the Eastern Alps based on gravity and seismic refraction data     

Stephan Mueller  Manik Talwani 《Pure and Applied Geophysics》1971,85(1):226-239

Summary Existing gravity and seismic refraction data are used to deduce a crustal cross section across the Eastern Alps along the meridian 11°.4 East. The results suggest that a high density body of the Ivrea type is present under the southern margin of the Alps, that the Apennines do not have a crustal root extending to a depth of 50 km and that a profound discontinuity extending to the base of the crust exists between the Apennines and the Po Valley.Lamont-Doherty Contribution No. 1590.  相似文献   

Low-temperature heat capacity of magnesioferrite (MgFe2O4)     

Stephan Klemme  Martin Ahrens 《Physics and Chemistry of Minerals》2005,32(5-6):374-378

The low-temperature heat capacity of magnesioferrite (MgFe₂O₄) was measured between 1.5 K and 300 K, and thermochemical functions were derived from the results. No heat capacity anomaly was observed. From our data, we suggest a standard entropy (298.15 K) for magnesioferrite of 120.8±0.6 J mol⁻¹ K⁻¹, which is about 2.4 J mol⁻¹ K⁻¹ higher than previously reported calorimetric studies; but is in rough agreement with predictions from sets of internally consistent thermodynamic data.  相似文献   

Do clay mineral dissolution rates reach steady state?     

Stephan J. Köhler  Dirk Bosbach 《Geochimica et cosmochimica acta》2005,69(8):1997-2006

The temporal evolution of natural illite du Puy dissolution rates was measured from Si release rates in single-pass flow-through experiments lasting at least 100 days at 25°C and pH ranging from 2 to 12. Si release rates decreased by a factor of five and three at pH 12 and 2, respectively, during the experiments. These observations are interpreted to stem from changes in illite du Puy reactive surface area during these experiments. As the edges of clay minerals dissolve faster than the basal planes, dissolution tends to change clay mineral morphology decreasing the percentage of reactive edge sites. This continuously changing morphology prevents illite dissolution rates from attaining steady state during laboratory experiments lasting 100 to 200 days. A similar temporal decrease in dissolution rates is evident for many different sets of clay mineral dissolution rate data available in the literature. It seems reasonable, therefore, to expect that clay mineral dissolution does not attain steady state in nature, but rather their dissolution rates decrease continuously during their dissolution.  相似文献   

Moho depth and three-dimensional P and S structure of the crust and uppermost mantle in the Eastern Mediterranean and Middle East derived from tomographic inversion of local ISC data   总被引：1，自引：0，他引：1  

Ivan Koulakov  Stephan V. Sobolev 《Geophysical Journal International》2006,164(1):218-235

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Earthquakes in Switzerland and surrounding regions during 2005     

Nicolas Deichmann  Manfred Baer  Jochen Braunmiller  Stephan Husen  Donat F?h  Domenico Giardini  Philipp K?stli  Urs Kradolfer  Stefan Wiemer 《Eclogae Geologicae Helvetiae》2006,99(3):443-452

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The oxygen isotope fractionation behaviour of kyanite in experiment and nature     

Andreas Tennie  Radegund Hoffbauer  Stephan Hoernes 《Contributions to Mineralogy and Petrology》1998,133(4):346-355

The oxygen isotope fractionation between kyanite and calcium carbonate has been investigated experimentally at four temperatures in the range between 625 and 775 °C at 13 kbar. Because of low exchange rates, the isotopic reaction was enhanced by polymorphic transformation of andalusite to kyanite. With this experimental modification a close approach to equilibrium was reached in all runs. The temperature dependence of the equilibrium fractionation is described by the equation 1000 ln _ky-cc=−2.62×10⁶/T ². Application of the experimental results to natural quartz-kyanite-garnet assemblages indicates the preservation of the oxygen isotope composition of kyanite acquired during its formation, reflecting its extremely low oxygen diffusivity. This refractory behaviour restricts the use of kyanite for thermometry but opens the possibility to use its O-isotope composition as an indicator for recognition of polymetamorphic rock histories and reconstruction of the prograde evolution of a metamorphic sequence. Received: 8 June 1998 / Accepted: 24 August 1998  相似文献   

Water transport and mixing in the North Frisian Wadden Sea — Results of numerical investigations     

Stephan Dick  Wolfgang Schönfeld 《Ocean Dynamics》1996,48(1):27-48

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On the last explosions of carbonatite pipe G3b, Gross Brukkaros, Namibia     

Volker Lorenz  Stephan Kurszlaukis 《Bulletin of Volcanology》1997,59(1):1-9

 Pipe G3b is part of the Upper Cretaceous carbonatitic Gross Brukkaros Volcanic Field in southern Namibia. The pipe represents the root zone of a diatreme and is located 2800 m west of the rim of Gross Brukkaros, a downsag caldera. The pipe is exposed approximately 550 m below the original Upper Cretaceous land surface. It cuts down into its own feeder dyke, 0.3 m thick. The pipe coalesced from two small pipes and in plan view is 19 m long and 12 m wide. It consists of fragmented Cambrian Nama quartzites and shales of the Fish River subgroup. Despite intensive brecciation, the stratigraphic sequence of the country rocks is almost preserved in the pipe. In addition, the feeder dyke became fragmented too and can be traced in a 2- to 3-m-wide zone full of carbonatite blocks along the southern margin of the pipe. The void space of the breccia is 30–50% in volume. Finally, after the disruption of country rocks and feeder dyke, a little carbonatite magma intruded some of the void space. The breccia of pipe G3b is considered to represent a root zone at the transition from the feeder dyke into a diatreme above. Formation of the breccia required a shock wave thought to have been associated with a last explosion of the diatreme immediately above the present level of exposure. The explosion can be shown to have been phreatomagmatic in origin. Received: 11 October 1996 / Accepted: 6 March 1997  相似文献   

Volcanological features of a low-viscosity melt: the carbonatitic Gross Brukkaros Volcanic Field, Namibia     

Stephan Kurszlaukis  Volker Lorenz 《Bulletin of Volcanology》1997,58(6):421-431

 In the Upper Cretaceous Gross Brukkaros Volcanic Field, southern Namibia, a radial dyke system surrounds a dome structure and its 74 closely related carbonatite diatremes. This paper focuses on volcanological features which seem to be typical for a low-viscosity melt in various settings such as dykes, sills and diatremes. The total or near absence of vesicles in carbonatite ash grains and lapilli inside the diatremes is evidence against explosive exsolution of volatile phases and in favour of a phreatomagmatic fragmentation mechanism and thus for a phreatomagmatic eruption mechanism of the carbonatite diatremes. Received: 15 August 1996 / Accepted: 13 January 1997  相似文献