Reassessment of the garnet-clinopyroxene Fe−Mg exchange thermometer: I. Evaluation of the Pattison and Newton (1989) experiments     

L. Y. Aranovich  D. R. M. Pattison 《Contributions to Mineralogy and Petrology》1995,119(1):16-29

This is Part 1 of a two-part study on the garnet(Grt)-clinopyroxene(Cpx) Fe−Mg exchange equilibrium widely used in geothermometry of amphibolites, granulites and eclogites. The experimental data set previously published by Pattison and Newton (PN) on this equilibrium comprises potentially the largest source of data used for extraction of thermodynamic properties for Grt and Cpx and for formulation of a new thermometer expression (Part 2 of this study). However, the experiments suggested unusual Grt and Cpx solution properties and resulted in a geothermometer expression that generally returns low temperatures for granulites. To verify the reliability of the experiments, and to test the experimental technique of Grt buffering used in the PN study, 69 of the 125 PN runs were reanalysed using wavelength dispersive spectroscopic analysis guided by backscattered electron images. Special attention was given to analysis of compositional changes in Grt in addition to Cpx. With minor exceptions, the reanalysis supports the analytical results of the original PN study. The mechanism of equilibration in the runs was a multicomponent solution-precipitation process involving dissolution of metastable Grt and Cpx starting materials and precipitation of newly formed Cpx and Grt, the latter assumed to represent equilibrim compositions. The experiments cannot be regarded either as reversed or as strictly bracketing. Nevertheless, Cpx compositional parameters, including Mg#, Na, Ca and Al, show the same smooth variations with temperature, pressure and composition as found by PN, suggestive of a close approach to equilibrium. Grt in run products retained the moderate heterogeneity of the starting Grt, although there are subtle compositional trends indicating small changes in Grt Mg# consistent with mass balance constraints. These results uphold the essential validity of the technique of Grt buffering used in the experiments. Nevertheless, it is possible that the final Grt compositional may not coincide with the nominal starting Grt compositions, requiring assignment of compositional uncertainties to Grt for purposes of thermodynamic modelling of the data. Cpx analyses also require assignment of non-zero compositional uncertainties.  相似文献   

History of the Hungarian Holocene mollusc fauna     

Levente Füköh 《GeoJournal》1995,36(2-3):255-259

Based on phylogenetical, palaeoecological and biostratigraphical studies on the Holocene malacofauna of Hungarian medium high mountains and flatlands, four faunal periods could be recognised in the mountains, while three ones on the flat regions. They are defined by correlation (using anthracotomical, palynological, vertebrate palaeontological, archaeological and radiometric data, as well as by the Central European malacozones) as biozones of regional value.The mollusc fauna may be regarded as the main palaeoecological indicator for the Hungarian Quaternary, because it is generally abundant, in contrast to the vertebrate fauna. On the other hand, the Hungarian Quaternary fauna mostly consists of species still living in the area. The ecological demands of recent species are generally well known. Most of the ecological data about the Quaternary formations were yielded by the examination of the Hungarian mollusc fauna.The Quaternary mollusc fauna is not only suitable for palaeoecological reconstructions but it helps in the stratigraphical division of the sequences, as well, mainly due to Endre Krolopp's activity (Krolopp 1983). This study and investigations of Holocene molluscs enabled us to make an attempt (Füköh 1990) in describing the history of the last ten thousand years.  相似文献   

Noble gases dissolved in groundwater in a volcanic aquifer: Helium isotopes in the Kumamoto Plain     

Y. Mahara 《Environmental Geology》1995,25(4):215-224

This study Investigates a tracing method using dissolved noble gases to survey the groundwater flow in a large groundwater basin. The tracing method is based on measuring the concentrations of noble gases and the ratio of helium isotopes in groundwater samples. Since it is very difficult to detect trace amounts of noble gases and helium with high accuracy in a 15-ml groundwater sample, dissolved gases were extracted and purified, then a high-resolution mass spectrometer was used for measurement and comparison with standard samples. We used this method with samples from a confined aquifer formed by the deposition of pyroclastic flow in the Kumamoto Plain on the west side of Mt. Aso in central Kyushu, Japan. The groundwater basin under the plain is divided into four small basins, based on the helium concentrations and isotope ratios, with two major groundwater flows. One flow is buried by the Aso pyroclastic flow along the old Kase River; the other is along the Tsuboi River Valley. These two groundwater flows were identified from the different helium isotope-ratios. The helium component from the deep mantle is mixed into the groundwater under the Kumamoto Plain. Finally, data on the concentrations and ratios of³He to⁴He in groundwater samples were used to determine the location of faults in the volcanic aquifer.  相似文献   

Comparison Of Three Uncertainty-Analysis Methods To Assess Impacts On Groundwater Of Constituents Leached From Land-Disposed Waste     

K. Ünlü  J. C. Parker  P. K. Chong 《Hydrogeology Journal》1995,3(2):4-18

Assessment of the environmental fate and behavior of constituents that have the potential to leach from waste-disposal pits that are associated with petroleum exploration and production activities is a problem of interest to industry and regulatory agencies. A stochastic modeling approach for the migration of constituents in soil and groundwater was developed to assess the impact on groundwater at receptors that are downgradient from a waste pit. The model evaluates uncertainties in constituent concentrations in groundwater due to uncertainties in waste-composition and hydrogeologic properties of waste sites, and it determines the probability distributions of constituent concentration at receptor points by using Monte Carlo (MC), First-Order (FO), and Point-Estimate (PE) methods. Application of the FO and PE methods to assess probability distributions requires an assumption of the form of the probability density function for concentration at a receptor point. A log-normal distribution is employed here. A comparison of the three uncertainty-analysis methods is performed to evaluate the efficiency and accuracy of the FO and PE methods relative to the MC method. Results suggest that for non-reactive and conservative constituents the level of accuracy provided by FO method is similar to that of the MC method. The computational effort for the FO method is about 1 percent of that for the MC method. For nonconservative constituents, the FO method compared less favorably with the MC results. Thus, the use of the MC method is warranted, for nonconservative constituents or for cases where a higher degree of precision in the probability distribution is needed. RÉSUMÉ: L'industrie et les organismes de contrôle s'intéressent particulièrement au problème de la prédiction du devenir et du comportement environnemental de composés susceptibles de lixivier des pollutants à partir de puits de stockage de déchets associés à des zones d'exploration et de production pétrolières. Une modélisation stochastique de la migration de composées dans le sol et les eaux souterraines est proposée en vue de prédire l'impact sur les eaux souterraines en des points de prélèvement situés en aval-gradient d'un puits de stockage. Le modèle fournit une estimation des incertitudes sur les teneurs des composés dans les eaux souterraines en fonction de la composition des déchets et des propriétés hydrogéologiques des sites de stockage; il détermine les distributions de probabilité de la concentration des composés à des points de prélèvement au moyen des méthodes de Monte-Carlo (MC), du Premier Ordre (PO) et de l'Estimation Ponctuelle (EP). Le recours aux méthodes PO et EP pour prédire les distributions de probabilité impose une hypothèse sur la forme de la fonction de densité de probabilité pour la concentration en un point de prélèvement. Une distrubution log-normale est utilisée ici. Une comparaison des trois méthodes d'analyse de l'incertude a été réalisée afin d'estimer l'efficacité et la précision des méthodes PO et EP par rapport à la méthode MC. Les résultats indiquent que, pour des composés conservatifs, le degré de précision atteint par la méthode PO est comparable à celle de la méthode MC. La puissance de calcul requise par la méthode PO est 1% environ de celle nécessaire pour la méthode MC. Pour des composés non conservatifs, la comparaison avec la méthode MC est moins favorable à la méthode PO. Par conséquent, la méthode MC est préférable pour les composés non conservatifs ou dans les cas où un meilleur degré de précision de la distribution de probabilité est nécessaire. RESUMEN: La evaluación del comportamiento de constituyentes lixiviables desde vertidos de residuos asociados a actividades de exploración y producción petrolífera, así como su posible impacto ambiental, es un problema de interés para la industria y las agencias reguladoras. Se ha desarrollado una modelación estocástica para estudiar la migración de los constituyentes en el suelo y el agua subterránea, con el objetivo de evaluar su impacto en receptores situados aguas abajo de un vertido. El modelo evalúa las incertidumbres en las concentraciones de los constituyentes debidas a las incertidumbre en la composición de los residuos y de las propiedades hidrogeológicas de la zona de vertido y determina las distribuciones de probabilidad de dichas concentraciones en puntos de recepción mediante los métodos de Monte Carlo (MC), Primer-Orden (FO) y Estimación Puntual (PE). La aplicación de los métodos FO y PE para evaluar las distribuciones de probabilidad reqiere suponer conocida la forma de la función de densidad de probabilidad para la concentración en el punto receptor. En este caso, se emplea una distribución log-normal. Se lleva a cabo una comparación entre los tres métodos de análisis de errores para evaluar la eficiencia y exactitud de los métodos FO y PE respecto al MC. Los resultados sugieren que para constituyentes conservativos no-reactivos, el nivel de exactitud suministrado por el método FO es comparable con el del MC. El esfuerzo computacional para el método FO, en cambio, es alrededor del 1% del método MC. Para constituyentes no conservativos, es método FO no compara tan favorablemente frente a los resultados del MC. Por tanto, el uso del método MC está obligado para constituyentes no conservativos y para casos en los que se requiere un alto nivel de precisión en la distribución de probabilidad.  相似文献   

Centuries of artificial recharge on the southern edge of the Sierra Nevada (Granada,Spain)   总被引：1，自引：0，他引：1  

A. Pulido-Bosch  Y. Ben Sbih 《Environmental Geology》1995,26(1):57-63

In the Alpujarra (southern Spain), every year between the March and June, an ancestral practice continues in the form of diverting water from the rivers by way of an extensive network of irrigation channels (acequias) to well-defined, highly permeable areas. This practice, known ascareos, constitutes an ancient example of artificial recharge. The objective is to guarantee a supply of drinking water during the dry months, as well as improve the physicochemical characteristics of the water. In addition, this system helps maintain moisture in the immediate environment, and thus has a positive effect on local vegetation.  相似文献   

The Sudbury Structure (Ontario,Canada): a tectonically deformed multi-ring impact basin     

A. Deutsch  R. A. F. Grieve  M. Avermann  L. Bischoff  P. Brockmeyer  D. Buhl  R. Lakomy  V. Müller-Mohr  M. Ostermann  D. Stöffler 《International Journal of Earth Sciences》1995,84(4):697-709

The occurrence of shock metamorphic features substantiates an impact origin for the 1.85 Ga old Sudbury Structure, but this has not been universally accepted. Recent improvements in knowledge of large-scale impact processes, combined with new petrographic, geochemical, geophysical (LITHOPROBE) and structural data, allow the Sudbury Structure to be interpreted as a multi-ring impact structure. The structure consists of the following lithologies: Sudbury Breccia —dike breccias occurring up to 80 km from the Sudbury Igneous Complex (SIC); Footwall rocks and Footwall Breccia — brecciated, shocked crater floor materials, in part thermally metamorphosed by the overlying SIC; Sublayer and Offset Dikes, Main Mass of the SIC and Basal Member of the Onaping Formation (OF) — geochemically heterogeneous coherent impact melt complex ranging from inclusion-rich basal unit through a dominantly inclusion-free to a capping inclusion-rich impact melt rock; Grey Member of OF — melt-rich impact breccia (suevite); Green Member of OF — thin layer of fall back ejecta; Black Member of OF — reworked and redeposited breccia material; Onwatin and Chelmsford Formations — post-impact sediments. Observational and analytical data support an integrated step-by-step impact model for the genesis of these units. Analysis of the present spatial distribution of various impact-related lithologies and shock metamorphic effects result in an estimated original rim-to-rim diameter of the final crater of 200 or even 280 km for the Sudbury Structure, prior to tectonic thrusting and deformation during the Penokean orogeny.  相似文献   

Grim4-C1, -C2p: combination solutions of the global earth gravity field     

Ch. Reigber  P. Schwintzer  W. Barth  F. H. Massmann  J. C. Raimondo  A. Bode  H. Li  G. Balmino  R. Biancale  B. Moynot  J. M. Lemoine  J. C. Marty  F. Barlier  Y. Boudon 《Surveys in Geophysics》1993,14(4-5):381-393

On the basis of the GRIM4-S1 satellite-only Earth gravity model, being accomplished in a common effort by DGFI and GRGS, a combination solution, called GRIM4-C1, has been derivcd using 1° × 1° mean gravity anomalies and 1° × 1° Seasat altimeter derived mean geoid undulations. In the meantime improvements could be achieved by incorporating more tracking data (GEOSAT, SPOT2-DORIS) into the solution, resulting in the two new parallel versions, the satellite-only gravity model GRIM4-S2 and the combined solution GRIM4-C2p (preliminary). All GRIM4 Earth gravity models cover the spectral gravitational constituents complete up to degree and order 50.In this report the emphasis is on the discussion of the combined gravity models: combination and estimation techniques, capabilities for application in precise satellite orbit computation and accuracies in long wavelength geoid representation. It is shown that with the new generation of global gravity models general purpose satellite-only models are no longer inferior to combination solutions if applied to satellite orbit restitution.  相似文献   

Congratulation to Prof. Heinz Ambühl's 65th Anniversary     

Hans Rudolf Bürgi 《Aquatic Sciences - Research Across Boundaries》1993,55(3):157-160

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Das erdmagnetische Feld im Jahr 1992 nach Messungen des Erdmagnetischen Observatoriums Wingst     

Günter Schulz 《Ocean Dynamics》1993,45(3):215-218

Ohne Zusammenfassung  相似文献   

Die Lagerungsverhältnisse der Altvulkanite     

Prof. Dr. Walther Klüpfel 《International Journal of Earth Sciences》1962,52(1):514-540

Zusammenfassung Es werden die Lagerungsverhältnisse der altvulkanischen Bildungen erörtert: Die fördertreue Lagerung der Tuffe und die teils kongruente, teils überschneidende, teils fördertreue Lagerung der Intrusivgruppen. Die Lagerung derselben beruht auf dem jeweiligen Verhältnis von Senkung und Hebung. Im Gegensatz dazu ist die inverse Lagerung der Scheiben innerhalb einer Intrusivgruppe bei stationärer Lage des Gebirges auf das zunehmende spezifische Gewicht der Schmelzen zurückzuführen. Diese Lagerung steht im Widerspruch zur Förderfolge. Dieser Befund bestätigt die Intrusivnatur der vorquartären Laven.Die Graben- und Kammerbasalte werden auf den Abriß eines Grabenkeils infolge der Horizontalen Dehnung und auf eine progressive Kammerbildung zurückgeführt. Sie gibt einen Hinweis auf den Raumgewinn nach unten. Es folgen Erörterungen über die Lagerungsbeziehungen der Intrusivkörper zu den Sedimenten und Tuffen. Am Schluß wird auf die methodische Anwendung der erkannten Gesetzmäßigkeiten hingewiesen. Im Anhang folgt eine Stellungnahme zu den bei der Diskussion vorgebrachten Einwänden.

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Pyroclasts are deposited in accordance with their eruption. Intrusives are found in congruent, overlapping, or in eruption-accordant positions, consequent to tectonic rise and subsidence. In stable areas the reversed succession within the volcanic complex follows an increased specific weight of the magma. Reversed successions of volcanic series corroborate the intrusive origin of the prequaternary lavas. The graben and chamber basalts depend on wedge-shaped graben subsidence, and on progressive formation of chambers.

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Résumé On examine ici les aspects des stratifications des formations volcaniques anciennes, en particulier la stratification des tuffs et celle des roches intrusives. La stratification de ces dernières est due aux diverses formes d'affaisement et de soulèvement. En contraste avec cela, la disposition inverse des plaques à l'intérieur d'un groupe de roches intrusives dans une position stationnaire de la montagne doit s'expliquer par l'accroissement du poids spécifique du magma. Cette disposition se trouve en opposition avec l'ordre d'arrivée. Cette constation permet de confirmer la nature intrusive de «laves» préquaternaires. Les basaltes des fossés et les basaltes des salles ont attribués à un graben par suite de l'extension horizontale et à une formation progressive de salles. Celle-ci apporte une indication sur le gain d'espace réalisé vers le bas.A la fin on attire l'attention sur les aspects de la stratification des corps intrusifs par rapport aux sédiments et aux tuffs ainsi que sur l'application méthodique deces résultats. Dans l'appendice suit une prise de position par rapport aux objections formulées en cours de discussion.

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