Simulation of active tectonic processes for a convecting mantle with moving continents   总被引：1，自引：0，他引：1  

Valeriy Trubitsyn  Mikhail Kaban  Walter Mooney  Christoph Reigber  Peter Schwintzer 《Geophysical Journal International》2006,164(3):611-623

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Impact of global warming on the interannual and interdecadal climate modes in a coupled GCM     

Z.-Z. Hu  L. Bengtsson  E. Roeckner  M. Christoph  A. Bacher  J. M. Oberhuber 《Climate Dynamics》2001,17(5-6):361-374

In this study, we investigated the impact of global warming on the variabilities of large-scale interannual and interdecadal climate modes and teleconnection patterns with two long-term integrations of the coupled general circulation model of ECHAM4/OPYC3 at the Max-Planck-Institute for Meteorology, Hamburg. One is the control (CTRL) run with fixed present-day concentrations of greenhouse gases. The other experiment is a simulation of transient greenhouse warming, named GHG run. In the GHG run the averaged geopotential height at 500?hPa is increased significantly, and a negative phase of the Pacific/North American (PNA) teleconnection-like distribution pattern is intensified. The standard deviation over the tropics (high latitudes) is enhanced (reduced) on the interdecadal time scales and reduced (enhanced) on the interannual time scales in the GHG run. Except for an interdecadal mode related to the Southern Oscillation (SO) in the GHG run, the spatial variation patterns are similar for different (interannual?+?interdecadal, interannual, and interdecadal) time scales in the GHG and CTRL runs. Spatial distributions of the teleconnection patterns on the interannual and interdecadal time scales in the GHG run are also similar to those in the CTRL run. But some teleconnection patterns show linear trends and changes of variances and frequencies in the GHG run. Apart from the positive linear trend of the SO, the interdecadal modulation to the El Niño/SO cycle is enhanced during the GHG 2040?～?2099. This is the result of an enhancement of the Walker circulation during that period. La Niña events intensify and El Niño events relatively weaken during the GHG 2070?～?2090. It is interesting to note that with increasing greenhouse gas concentrations the relation between the SO and the PNA pattern is reversed significantly from a negative to a positive correlation on the interdecadal time scales and weakened on the interannual time scales. This suggests that the increase of the greenhouse gas concentrations will trigger the nonstationary correlation between the SO and the PNA pattern both on the interdecadal and interannual time scales.  相似文献   

Validation of vulnerability mapping methods by field investigations and numerical modelling   总被引：4，自引：1，他引：3  

Christoph Neukum  Heinz Hötzl  Thomas Himmelsbach 《Hydrogeology Journal》2008,16(4):641-658

Vulnerability maps illustrate the potential threat of contaminants to groundwater and can be considered as important tools for land-use planning and related legislation. For karst areas with characteristic preferential infiltration conditions, vulnerability maps are also excellent tools for source and resource protection. However, the resulting qualitative maps are often inconsistent and even contradictive and thus might lead to inconclusive vulnerability assessments. The results of a validation of vulnerability maps produced using four different methods, DRASTIC, GLA, PI and EPIK, are reported for a karst area in southwest Germany. By means of measured hydraulic and transport parameters of the geological sequence, numerical simulations were used based on a conceptual model for the area under study. The mean transit time through the unsaturated zone (resource protection) was used as the validation parameter. The study demonstrates that the highest level of accuracy is achieved with the GLA- and PI methods. Both DRASTIC and EPIK are not able to incorporate highly variable distributions and thickness of cover sediments and their protective properties in the respective mapping procedure. Thus, vulnerability maps produced with DRASTIC, EPIK, and related methods should be used with care when employed in vulnerability assessments for land use planning and related decision-making.

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Résumé  Les cartes de vulnérabilité illustrent la menace potentielle des contaminants envers les eaux souterraines, et peuvent être considérées comme des outils importants en matière d'aménagement foncier et de réglementation associée. Sur les domaines karstiques, caractérisés par des conditions d'infiltration préférentielle, ces cartes sont également d'excellents outils de protection des sources et des ressources. Cependant, les cartes qualitatives résultantes sont généralement incohérentes voire contradictoires, et peuvent par là-même mener à des évaluations de vulnérabilité peu concluantes. La présente étude expose les résultats de validation de cartes de vulnérabilité produites selon quatre méthodes différentes (DRASTIC, GLA, PI et EPIK), dans le cas d'un domaine karstique du sud-est de l'Allemagne. Par le biais des paramètres de transport et hydrauliques mesurés sur la séquence géologique, des simulations numériques basées sur un modèle conceptuel du secteur d'étude ont été utilisées. Les temps de transit moyens à travers la zone non saturée (protection de la ressource) ont été utilisés comme paramètres de validation. L'étude démontre que le niveau maximum de précision est obtenu par les méthodes GLA et PI. Dans la phase de cartographie, les méthodes EPIK et DRASTIC sont incapables d'intégrer une forte variabilité dans les distributions et les épaisseurs de sédiments de couverture, ainsi que dans leurs potentiels de protection. Aussi, les cartes de vulnérabilité produites par les méthodes DRASTIC et EPIK doivent être utilisées avec précaution dans le cadre des évaluations de vulnérabilité à but décisionnaire pour les aménagements fonciers.

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Resumen  Los mapas de vulnerabilidad ilustran la amenaza potencial de contaminantes para el agua subterránea y pueden ser considerados herramientas importantes para planeamiento del uso de la tierra y legislación relacionada. Para áreas cársticas con sus características condiciones de infiltración preferencial, los mapas de vulnerabilidad son también excelentes herramientas para protección de fuentes y recursos. Sin embargo, los mapas cualitativos resultantes son frecuentemente inconsistentes y hasta contradictorios y por lo tanto podrían conducir a evaluaciones de vulnerabilidad no concluyentes. Los resultados de una validación de mapas de vulnerabilidad producidos usando cuatro métodos diferentes, DRASTIC, GLA, PI y EPIK, son presentados aquí para un área cárstica en Alemania suroccidental. Se usaron simulaciones numéricas usando parámetros hidráulicos y de transporte medidos de la secuencia geológica y basándose en un modelo conceptual del área en estudio. El tiempo promedio de tránsito a través de la zona no saturada (protección del recurso) fue utilizado como el parámetro de validación. El estudio demuestra que el máximo nivel de precisión es alcanzado con los métodos GLA y PI. DRASTIC y EPIK no fueron capaces de incorporar distribuciones altamente variables ni espesor de sedimentos de cubierta y sus propiedades protectivas en el respectivo procedimiento de elaboración de mapas. Por lo tanto los mapas de vulnerabilidad producidos con DRASTIC, EPIK y métodos relacionados deberían ser usados con cuidado cuando se usen en evaluaciones de vulnerabilidad para planeamiento del uso de tierra y toma de decisiones relacionadas.

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Solution-precipitation creep and fluid flow in halite: a case study of Zechstein (Z1) rocksalt from Neuhof salt mine (Germany)     

Zsolt Schléder  János L. Urai  Sofie Nollet  Christoph Hilgers 《International Journal of Earth Sciences》2008,97(5):1045-1056

Zechstein (Z1) rocksalt from the Fulda basin, from the immediate vicinity of the Hessen potash bed is folded into tight to isoclinal folds which are cut by an undeformed, 1 cm thick, coarse-grained halite vein. Microstructures were investigated in etched, gamma-irradiated thin sections from both the wall rock and the vein. The lack of synsedimentary dissolution structures and the widespread occurrence of plate-shaped and hopper grains in the wall-rock suggests that the sedimentary environment was perennial lake. Deformation microstructures are in good agreement with solution-precipitation creep process, and salt flow under very low differential stress. Strength contrast between anhydrite-rich and anhydrite-poor layers caused the small scale folding in the halite beds. The vein is completely sealed and composed mainly of euhedral to subhedral halite grains, which often overgrow the wall-rock grains. Those microstructures, together with the presence of occasional fluid inclusion bands, suggest that the crystals grew into a solution-filled open space. Based on considerations on the maximum value of in-situ differential stress, the dilatancy criteria, the amount of released fluids from the potash bed during metamorphism and the volume change, it is proposed that the crack was generated by hydrofracturing of the rocksalt due to the presence of the salt-metamorphic fluid at near-lithostatic pressure.  相似文献   

Paleozoic basin development in northern Chile (21°–27°S)     

Dr. Heinrich Bahlburg  Dr. Christoph Breitkreuz  Prof. Dr. Werner Zeil 《International Journal of Earth Sciences》1987,76(2):633-646

The oldest non-metamorphic sediments of northern Chile (21?–27?S) are of Early Ordovician age. The partly strong volcanic influence in the clastic series of the Pre-Cordillera and the Puna might be connected with the extensive Ordovician magmatism on the eastern side of the Argentinian Puna. The geochemical character of the tholeiitic intercalations in the pelites and turbidites of the »Complejo Igneo-Sedimentario del Cordon de Lila« (C.I.S.L.) in the Pre-Andean Depression indicates a ?Lower Ordovician extensional regime in this area. A positive area (»Arco Puneño«) encompassing the whole width of the present-day western Central Andes developed during the subsequent orogenic phase (»Fase Oclóyica«), resulting in the absence of Silurian strata in Northern Chile. During the Devonian/Carboniferous, two areas of marine facies can be distinguished. In the Coastal Cordillera thick flysch sediments were deposited longitudinally in a N-S striking trough. In the east, in what is now the Pre-Andean Depression and High Cordillera, thick sandstone series accumulated on the western shelf of the Arco Puneno. Carboniferous tectonic movements led to the formation of a shallow marine platform in the west on which clastic sediments, limestones and volcanics were deposited during the Upper Carboniferous-Permian. Simultaneously, extensive volcanism developed in the Pre- and High Cordillera accompanied by predominantly terrestrial sedimentation. A general westward migration of the orogenic zones took place along with repeated phases of rifting and accretion in the Central Andes during the Paleozoic. Eastward directed erosive subduction prevailed since the breakup of Pangea.  相似文献   

A longitudinal seismic reflection profile of the Reykjanes Ridge: Part I — Evidence for west-flowing bottom water     

P.R. Vogt  G.L. Johnson 《Earth and Planetary Science Letters》1973,18(1):45-48

A longitudinal seismic reflection profile along the east flank of Reykjanes Ridge, from Charlie fracture zone to the vicinity of Iceland, has important implications both for bottom water movement and for hypotheses of crustal generation at the axis of the mid-oceanic ridge. In this paper bottom water movement is considered. Between 52°N and 57°N Reykjanes Ridge is cut by about 12 fractures whose trend, inferred from other data, is approximately east-west. North of 57° there is little or no indication of east-west fracturing. Fracture valley bottoms are typically 1 km below the surrounding basement level; sediment fills are about 0.5 km; present bottoms are 2.1 to 2.8 km below sea level. Depositional asymmetry is apparent in 9 cases, 7 of which have the deepest and generally least reflective bottom at the northern edge. This suggests predominately west-flowing bottom currents, carrying Norwegian Sea overflow water through the fracture valleys, a result consistent with previously published data.  相似文献   

Evidence for sea-floor spreading in the Cayman Trough     

T.L. Holcombe  P.R. Vogt  J.E. Matthews  R.R. Murchison 《Earth and Planetary Science Letters》1973,20(3):357-371

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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   

Deutung von Eigenfrequenzen in Zweikreiselkompaßsystemen     

Dr. Peter Christoph 《Ocean Dynamics》1969,22(2):49-56

Zusammenfassung Der Versuch, die experimentell durch Messung an handelsüblichen Zweikreiselkompaßsystemen festgestellten Eigenfrequenzen mit theoretisch berechneten Werten in Übereinstimmung zu bringen, indem die System-Trägheitsmomente Berücksichtigung finden, bringt keinen Erfolg. Erst die zusätzliche Beachtung der Elastizität der Kreiselachsen bringt eine befriedigende Übereinstimmung zwischen Messung und Theorie.

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Interpretation of the natural frequencies in double-gyro compass systems

Summary An attempt to harmonize the natural frequencies measured at commercial double-gyro compass systems with theoretically computed values by taking account of the moments of inertia of the systems proved unsuccessful. A satisfactory agreement between measurement and theory is reached only after additionally taking into account the elasticity of the gyro axes.

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Interprétation des fréquences propres dans le système des compas à deux gyroscopes

Résumé Quand on essaye par des mesures expérimentales, de mettre en accord les fréquences propres constatées avec leurs valeurs calculées théoriquement dans les systèmes de compas à deux gyroscopes d'usage courant, en tenant compte des moments d'inertie des systèmes, on n'obtient aucun résultat. C'est seulement en prenant de plus en considération l'élasticité des axes des gyroscopes qu'on obtient un accord satisfaisant entre la mesure et la théorie.

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Kyanite-eclogite to amphibolite fades evolution of hydrous mafic and pelitic rocks,Adula nappe,Central Alps     

Christoph A. Heinrich 《Contributions to Mineralogy and Petrology》1982,81(1):30-38

In the southern Adula nappe (Central Alps), two stages of regional metamorphism have affected mafic and pelitic rocks. Earlier eclogite facies with a regional zonation from glaucophane eclogites to kyanite-hornblende eclogites was followed by a Tertiary overprint which varied from greenschist to high-grade amphibolite facies. Despite a common metamorphic history, contrasting equilibration conditions are often recorded by high-pressure mafic eclogite and adjacent predominantly lower-pressure pelite assemblages. This pressure contrast may be explained by different overprinting rates of the two bulk compositions during unloading. The rates are controlled by a mechanism in which dehydrating metapelites provide the H₂O required for simultaneous overprinting of enclosed mafic eclogites by hydration.Quantitative mass balance modelling based on corona textures is used to show that overprinting of metapelites during unloading involved dehydration reactions. The relatively rapid rate of dehydration reactions led to nearly complete reequilibration of metapelites to amphibolite facies assemblages.After the formation during high-pressure metamorphism of mafic eclogites, later lower-pressure reequilibration by hydration to amphibolites was slow, and therefore incomplete, because it depended on large scale transport of H₂O from adjacent, dehydrating metapelites.The facies contrast observed between rocks of different bulk composition is thus a consequence of the general tendency of metamorphic rocks to retain the most dehydrated assemblage as the final recorded state.  相似文献