GPS monitoring of vertical ground motion in northern Ardenne–Eifel: five campaigns (1999–2003) of the HARD project     

A. Demoulin  J. Campbell  A. De. Wulf  A. Muls  R. Arnould  B. Görres  D. Fischer  T. Kötter  M. Brondeel  D. Van. Damme  J. M. Jacqmotte 《International Journal of Earth Sciences》2005,94(4):515-524

We present the HARD project of GPS monitoring of vertical ground motion in NE Ardenne and Eifel (western Europe). Its main purposes are to get a better insight into the present-day rates of vertical ground motion in intraplate settings and to identify the various causes of these motions. Since 1999, we have carried out yearly campaigns of simultaneous GPS measurements at 12 sites situated so as to sample the different tectonic subunits of the study area and especially to record potential displacements across the seismogenic Hockai fault zone. Five campaigns (1999–2003) have been processed currently. Key issues of the data processing with the Gamit software are discussed and first results are presented. Though temporally consistent in many cases, the obtained vertical motion rates are spatially highly variable. They are also much too high (several mm/year) to support a tectonic interpretation, and a long-term influence of groundwater level variations is proposed to account for the observed motions. This influence should be distinguished from seasonal variations and from inter-survey variations linked to the varying degree of soil and subsoil drying off during the successive spring surveys.  相似文献   

Palaeomagnetic Studies of Miocene Ignimbrites from Nevada     

Wulf Achim Gose 《Geophysical Journal International》1970,20(3):241-252

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Anwendung der Endochronentheorie auf Salzgestein     

T. Richter  A. Wulf  K. -M. Borchert 《Rock Mechanics and Rock Engineering》1981,13(3):131-143

ZusammenfassungAnwendung der Endochronentheorie auf Salzgestein Es wird ein Stoffgesetz auf Grundlage der Endochronentheorie entwickelt, mit dem das Materialverhalten von Salzgestein beschrieben werden kann. Dafür werden die grundlegenden Vorstellungen dieser allgemeinen Theorie vorgestellt, wie sie von Valanis für Metalle und von Bazant-Bhat für Beton entwickelt wurde.Das Verformungsverhalten von Salzgestein, das durch eine ausgeprägte Kriechneigung geprägt ist, wird erläutert und durch ein rheologisches Modell beschrieben. Das rheologische Modell dient zur Bestimmung der in der Endochronenformulierung vorhandenen Materialfunktionen und Materialkonstanten. Das Stoffgesetz wird in tensorieller Weise formuliert, und es werden Hinweise für seinen Einbau in numerische Rechenmodelle gegeben.

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SummaryUse of the Endochronic Theory on Rock Salt On the basis of the endochronic theory a material model which can describe the behavior of rock salt is developed. This study presents and follows in a modified form the earlier work of Valanis in metals and Bazant-Bhat in concrete.The deformation characteristics of rock salt, subject to extensive creep, are described and explained by an analogous rheological model. This model is used to determine the material functions and constants for the endochronic formulation. The material law is written in tensor form and keys for its use in a computer program are supplied.

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RésuméMise en application de la théorie d'endochrones au niveau de la roche saline A partir de la théorie d'endochrones, l'on développe une loi des matières pouvant décrire le comportement de la roche saline. Dans cette optique, l'on présente les conceptions de base de cette théorie générale, telles qu'elles ont été développées par Valanis pour les métaux et par Bazant-Bhat pour le béton.Le comportement de déformation de la roche saline, caractérisé par une tendance marquée à ramper, est explicité et décrit à l'aide d'un modèle rhéologique. Le modèle rhéologique sert à la détermination des fonctions et constantes de matières, se trouvant dans la formulation d'endochrones. La loi des matières est formulée de facon tensorielle et l'on donne des instructions quant à son application au niveau des ordinateurs.

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Mit 5 Abbildungen  相似文献   

Raman spectroscopic study of PbCO3 at high pressures and temperatures     

Robert Minch  Leonid Dubrovinsky  Alexandr Kurnosov  Lars Ehm  Karsten Knorr  Wulf Depmeier 《Physics and Chemistry of Minerals》2010,37(1):45-56

Cerussite (PbCO₃) has been investigated by high-pressure and high-temperature Raman spectroscopy up to pressures of 17.2 GPa and temperatures of 723 K. Two pressure induced phase transitions were observed at about 8.0(2) and 16.0(2) GPa, respectively. The post-aragonite transition (PbCO₃-II) at 8.0(2) GPa is accompanied by softening of the v ₂-out-of-plane mode of the CO ₃ ^2? group and disappearance of the B_1g (v ₄-in-plane band of the CO ₃ ^2? group) mode. Stronger shifts of the carbonate group modes after the phase transition suggest that the new structure is more compressible. The formation of a second high-pressure polymorph begins at about 10 GPa. It is accompanied by the occurrence of three new bands at different pressures and splitting of the v ₁-symmetric C–O stretching mode of the CO ₃ ^2? group. The transitions are reversible on pressure release. A semi-quantitative phase diagram for PbCO₃ as a function of pressure and temperature is proposed.  相似文献   

Thermal expansion of gehlenite, Ca2Al[AlSiO7], and the related aluminates LnCaAl[Al2O7] with Ln=Tb, Sm     

L. Peters  K. Knorr  M. Knapp  W. Depmeier 《Physics and Chemistry of Minerals》2005,32(7):460-465

The thermal expansion of gehlenite, Ca₂Al[AlSiO₇], (up to T=830 K), TbCaAl[Al₂O₇] (up to T=1,100 K) and SmCaAl[Al₂O₇] (up to T=1,024 K) has been determined. All compounds are of the melilite structure type with space group Thermal expansion data was obtained from in situ X-ray powder diffraction experiments in-house and at HASYLAB at the Deutsches Elektronen Synchrotron (DESY) in Hamburg (Germany). The thermal expansion coefficients for gehlenite were found to be: α₁=7.2(4)×10⁻⁶ K⁻¹+3.6(7)×10⁻⁹ΔT K⁻² and α₃=15.0(1)×10⁻⁶ K⁻¹. For TbCaAl[Al₂O₇] the respective values are: α₁=7.0(2)×10⁻⁶ K⁻¹+2.0(2)×10⁻⁹ΔT K⁻² and α₃=8.5(2)×10⁻⁶ K⁻¹+2.0(3)×10⁻⁹ΔT K⁻², and the thermal expansion coefficients for SmCaAl[Al₂O₇] are: α₁=6.9(2)× 10⁻⁶ K⁻¹+1.7(2)×10⁻⁹ΔT K⁻² and α₃=9.344(5)×10⁻⁶ K⁻¹. The expansion-mechanisms of the three compounds are explained in terms of structural trends obtained from Rietveld refinements of the crystal structures of the compounds against the powder diffraction patterns. No structural phase transitions have been observed. While gehlenite behaves like a ’proper’ layer structure, the aluminates show increased framework structure behaviour. This is most probably explained by stronger coulombic interactions between the tetrahedral conformation and the layer-bridging cations due to the coupled substitution (Ca²⁺+Si⁴⁺)-(Ln ³⁺+Al³⁺) in the melilite-type structure. Electronic Supplementary Material Supplementary material is available for this article at  相似文献   

Measuring Tourist’s Water Footprint in a Mountain Destination of Northwest Yunnan, China     

Luc HENS  Robert DE WULF 《山地科学学报》2011,8(5):682-693

Monitoring and minimizing tourist’s water consumption is essential for the sustainable development of mountain destinations in the world. However, available data and a generally accepted protocol on such measurement are still limited. This study uses water footprint accounting to quantify tourist’s water demand in the Liming valley, a World Heritage site and a rapidly growing tourism destination in Northwest Yunnan, China. Both the water for direct and indirect use is taken into account based on the consump...  相似文献   

Thermodynamics of arsenates, selenites, and sulfates in the oxidation zone of sulfide ores: VI. Solubility of synthetic analogs of ahlfeldite and cobaltomenite at 25°C     

M. V. Charykova  V. G. Krivovichev  O. S. Yakovenko  V. V. Semenova  K. N. Semenov  W. Depmeier 《Geology of Ore Deposits》2012,54(8):638-646

The understanding of the mechanisms of the selenium behavior under near-surface conditions is an urgent problem of modern mineralogy and geochemistry, and is very important for solving environmental problems. The objective of this study is to synthesize analogs of ahlfeldite and cobaltomenite and to estimate their solubility in water. These analogs have been synthesized by mixing aqueous solutions of cobalt and nickel nitrates, respectively, and sodium selenite acidified with a solution of nitric acid. The obtained samples have been identified by X-ray diffraction and IR spectroscopy. The solubility has been determined by the isothermal saturation method in ampoules at 25°C, while the solubility products have been calculated using the Geochemist’s Workbench (GMB 7.0) software package. The solubility products of ahlfeldite and cobaltomenite are 10^?9.20 and 10^?9.44, respectively. The Eh-pH diagrams were calculated and plotted with the GMB 7.0 software package. The Eh-pH diagrams of the Ni-Se-H₂O and Co-Se-H₂O systems have been calculated for the average contents of these elements in underground water and their contents in acidic water of the oxidation zone of sulfide deposits. The formation of ahlfeldite and cobaltomenite under near-surface conditions is discussed.  相似文献   

Thermodynamics of arsenates, selenites, and sulfates in the oxidation zone of sulfide Ores: Part VII. Solubility of synthetic analogs of erythrite and annabergite at 25°C     

M. V. Charykova  V. G. Krivovichev  O. S. Yakovenko  V. V. Semenova  K. N. Semenov  W. Depmeier 《Geology of Ore Deposits》2013,55(7):525-531

Understanding the mechanisms of arsenic’s behavior under near-surface conditions is one of the actual problems of contemporary mineralogy and geochemistry and is important for solving environmental problems. The aim of this study is to synthesize analogs of erythrite and annabergite and to investigate their solubility in water. These phases have been synthesized by the boiling-dry of aqueous solutions of cobalt and nickel nitrates mixed with sodium hydroarsenate alkalized with NaOH. The samples obtained have been identified with electron microprobe, X-ray diffraction, and IR spectroscopy. Solubility has been determined by the isothermal saturation method in ampoules at 25°C. The solubility has been calculated using the Geochemist’s Workbench (GMB 7.0) software package. The measured solubilities of erythrite and annabergite are 10^?35.76 and 10^?36.43, respectively. Eh-pH diagrams were calculated and plotted using the GMB 7.0 software package. The database comprises the thermodynamic parameters of 46 elements, 47 main particles, 48 redox pairs, 552 particles in solution, 624 solid phases, and 10 gases. The Eh-pH diagrams of the Ni-As-H₂O and Co-As-H₂O systems were plotted for the average contents of these elements in the acidic waters in the oxidation zones of sulfide deposits. The formation of erythrite and annabergite under near-surface conditions is discussed.  相似文献   

Deciphering an Archean mantle plume: Abitibi greenstone belt,Canada     

Jaroslav Dostal  Wulf U. Mueller 《Gondwana Research》2013,23(2):493-505

The 2724–2722 Ma Stoughton-Roquemaure Group (SRG) of the Abitibi greenstone belt (the Archean Superior Province, Canada) is a ≤ 2 km thick komatiite–basalt succession intermittently exposed for about 50 km along strike. The ultramafic and mafic rocks occur mainly as pillowed, brecciated, and massive flows with well preserved spinifex textures in the komatiites. Volcanological, comparative stratigraphic and geochemical studies of the group along a volcanic marker horizon at the base of the succession allow the assessment of magma emplacement processes and mantle source rocks. Major feeder channels, secondary distributary tubes surrounded by pillowed flows with minor breccias and hyaloclastites display facies architecture of small volume flow fields (1–2 km³). Within the SRG, Al-depleted (ADK; Barberton-type) and Al-undepleted (AUK; Munro-type) komatiitic lavas are intercalated with tholeiitic basalt flows at a m- to 10s of m scale. Basalts and komatiites are inferred to be mantle plume-related; both rock types form two groups with characteristics of ADK and AUK including Al₂O₃/TiO₂ ~ 9–12 for ADK versus 17–22 for AUK, as well as (Gd/Yb)_n with > 1.3 versus ~ 1, respectively. The interdigitation of compositionally different flow units, limited extent of SRG volcanic rocks and facies architecture with the prevalence of small volume flows argue for a relatively small, heterogeneous mantle plume during the incipient stage of the evolution of the Archean Abitibi belt. Assuming that the scale of heterogeneities is comparable to the field expression of compositional changes and stratigraphy, it can be suggested that geochemical plume ‘layering’ is on 10s to 100s of m-scale. The evolution of this Archean mantle plume from inception to demise compares favorably with the Yellowstone hotspot which is assumed to have developed over 17 m.y. and had a diameter of about 300 km.  相似文献   

The last 40 ka tephrostratigraphic record of Lake Ohrid,Albania and Macedonia: a very distal archive for ash dispersal from Italian volcanoes     

B. Wagner  R. Sulpizio  G. Zanchetta  S. Wulf  M. Wessels  G. Daut  N. Nowaczyk 《Journal of Volcanology and Geothermal Research》2008

A 1075 cm long core (Lz1120) was recovered in the south-eastern part of the Lake Ohrid (Republics of Macedonia and Albania) and sampled for identification of tephra layers. Magnetic susceptibility investigations show rather high magnetic values throughout the core, with peaks unrelated to the occurrence of tephra layers but instead to the relative abundance of detrital magnetic minerals in the sediment. Naked-eye inspection of the core allowed us to identify of two tephra layers, at 896–897 cm and 1070–1075 cm. Laboratory inspection of the grain-size fraction > 125 μm allowed for the identification of a third cryptotephra at 310–315 cm. Major element analyses on glass shards of the tephra layers at 896–897 cm and 1070–1075 cm show a trachytic composition, and indicate a correlation with the regionally dispersed Y-3 and Y-5 tephra layers, dated at ca 30 and 39 cal ka BP. The cryptotephra at 310–315 cm has a mugearitic–benmoreitic composition, and was correlated with the FL eruption of Mt. Etna, dated at 3370 ± 70 cal yr BP. These ages are in agreement with five ¹⁴C AMS measurements carried out on plant remains and macrofossils from the lake sediments at different depths along the core.  相似文献